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NEOPLASMS OF THE COLON AND RECTUM

Comprehensive MBBS-Level Surgical Note

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A. DEFINITION

• CRC is the second leading cause of cancer death in non-smokers in Western countries (Bailey & Love, 28th ed.)
• It is largely preventable through surveillance colonoscopy and polypectomy
• Early-stage disease (Dukes' A) has a 5-year survival of ~95%, while stage D (distant metastases) has a survival of less than 10%
• The adenoma-carcinoma sequence provides a window for curative prevention

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B. EPIDEMIOLOGY

• Approximately 42,000 new cases per year in the UK; >150,000 per year in the USA
• CRC is the second most common cause of cancer death in the UK (Bailey & Love)
• In the USA, it is the third most common cancer in both sexes
• Incidence is highest in resource-rich countries (North America, Western Europe, Australia, New Zealand) and lowest in Africa, South Asia, and Central America
• Incidence is gradually rising in East Asian countries (Japan, South Korea, China) as these nations adopt Western dietary patterns

• Lifetime risk for the average individual is approximately 1 in 20 (5%)
• Incidence has been declining in older adults in Western countries due to widespread colonoscopic screening, but is increasing in adults under 50 years (early-onset CRC)

• Most cases occur in those over 50 years; median age at diagnosis is ~68 years
• Risk doubles approximately every decade after age 40
• Hereditary forms (FAP, Lynch syndrome) present earlier - often in the 3rd or 4th decade

• Slightly higher burden in men than women (56% versus 44% in UK data; Bailey & Love)
• Male-to-female ratio approximately 1.2:1 for colon cancer; rectal cancer has a more pronounced male predominance

• High risk: North America, Western Europe, Australia, New Zealand
• Intermediate risk: Japan, Eastern Europe
• Low risk: Sub-Saharan Africa, South and Central Asia
• Migrant populations from low-risk to high-risk countries acquire higher risk within one generation, confirming the dominant role of environmental (dietary) factors

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C. RELEVANT ANATOMY

Gross Anatomy of the Colon

• Caecum - lies in the right iliac fossa, intraperitoneal; 6-9 cm long; receives the terminal ileum; the appendix arises from its posteromedial wall
• Ascending colon - retroperitoneal (secondarily); rises from caecum to hepatic flexure on the right side
• Hepatic (right colic) flexure - lies under the right lobe of the liver and anterior to the right kidney; related to the second part of the duodenum
• Transverse colon - intraperitoneal; suspended by transverse mesocolon; crosses from right to left; most mobile segment
• Splenic (left colic) flexure - higher and more acute than hepatic flexure; related to the spleen, tail of pancreas, and left kidney
• Descending colon - retroperitoneal; runs from splenic flexure to sigmoid colon
• Sigmoid (pelvic) colon - S-shaped, intraperitoneal with its own mesentery (sigmoid mesocolon); variable length (15-50 cm); lies in the pelvis; most common site of diverticular disease and carcinoma
• Rectum - 12-15 cm long; begins at the rectosigmoid junction (S3 vertebra level); follows the sacral curve; no taenia coli, appendices epiploicae or mesentery; three lateral folds (valves of Houston) project into the lumen; ampulla is the dilated lower portion

Surface Anatomy

• Caecum: right iliac fossa, McBurney's point lies 1/3 of the distance from ASIS to umbilicus
• Ascending colon: right lateral flank
• Transverse colon: across the upper abdomen below the stomach
• Descending colon: left lateral flank
• Sigmoid colon: left iliac fossa
• Rectum: pelvis; posterior surface accessible on digital rectal examination

Surgical Anatomy of the Rectum

1. Upper third (11-15 cm from anal verge): covered by peritoneum anteriorly and laterally
2. Middle third (7-11 cm): covered by peritoneum anteriorly only
3. Lower third (0-7 cm): entirely extraperitoneal

Blood Supply

Venous Drainage

• Right colon: superior mesenteric vein (SMV) → portal vein → liver
• Left colon and rectum (upper): inferior mesenteric vein (IMV) → splenic vein → portal vein
• Lower rectum: middle and inferior rectal veins → internal iliac vein → systemic (IVC)
• Surgical significance: The dual venous drainage of the rectum explains why rectal cancer can produce lung metastases without liver metastases (via the systemic route)

Lymphatic Drainage

1. Epicolic nodes - on the bowel wall itself
2. Paracolic nodes - along the marginal artery
3. Intermediate nodes - along the named vessels (right/left/middle colic)
4. Principal/apical nodes - at the origin of SMA or IMA

Nerve Supply

• Sympathetic: From the lumbar splanchnic nerves via the superior and inferior mesenteric plexuses; stimulation inhibits peristalsis and contracts sphincters
• Parasympathetic: From the vagus nerve (caecum to splenic flexure) and pelvic splanchnic nerves/S2-S4 (left colon, rectum)
• Pelvic autonomic nerves: The hypogastric nerves (sympathetic) and pelvic splanchnic nerves (parasympathetic) run in the pelvis and are at risk during rectal dissection
  • Damage causes: bladder dysfunction (urinary retention), erectile dysfunction (males), retrograde ejaculation, and vaginal dryness (females)

Applied Anatomy

• Right-sided CRC: Produces occult blood loss → iron-deficiency anaemia; rarely obstructs because the lumen is wide and stool is liquid
• Left-sided CRC: Narrower lumen + formed stool → more likely to cause obstruction, change in bowel habit, pencil-thin stools
• Rectal CRC: Tenesmus, rectal bleeding, mucus discharge, urgency; low rectal tumours may involve the anal sphincter requiring abdominoperineal resection (APR)

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D. ETIOLOGY AND RISK FACTORS

I. Sporadic (70-80% of all CRC)

• High dietary fat, red meat, processed meat (haem iron, N-nitroso compounds)
• Low fibre, low calcium intake
• Obesity, physical inactivity
• Alcohol consumption (especially >3 units/day)
• Cigarette smoking
• Colonic microbiota dysbiosis

• Dietary fibre (reduces transit time and carcinogen exposure)
• Calcium and vitamin D
• Aspirin and NSAIDs (prostaglandin inhibition via COX-2; Bailey & Love notes substantial epidemiological evidence)
• HRT in postmenopausal women (modest protective effect)
• Physical exercise

II. Hereditary CRC Syndromes (~5-10%)

A. Familial Adenomatous Polyposis (FAP)

• Autosomal dominant mutation in the APC tumour suppressor gene (chromosome 5q21)
• APC mutation testing positive in 75% of FAP families (Schwartz's)
• Develops hundreds to thousands of adenomatous polyps after puberty
• 100% lifetime risk of CRC by age 50 if untreated (Schwartz's)
• Only ~1% of all CRC cases but provides the most insight into colorectal carcinogenesis
• Variants: Gardner's syndrome (desmoid tumours, osteomas, epidermoid cysts, mandibular osteomas, congenital hypertrophy of retinal pigment epithelium [CHRPE]); Turcot's syndrome (CNS tumours)
• Treatment: prophylactic surgery (total proctocolectomy or colectomy with ileorectal anastomosis)

B. Hereditary Non-Polyposis Colorectal Cancer (HNPCC / Lynch Syndrome)

• Autosomal dominant
• Mutation in DNA mismatch repair (MMR) genes: MLH1, MSH2, MSH6, PMS2
• Results in microsatellite instability (MSI) - hallmark of Lynch syndrome
• Accounts for ~3-5% of all CRC
• Lifetime risk of CRC: 50-80%
• Tumours predominantly right-sided
• Associated with endometrial cancer (most common extra-colonic cancer), ovarian, urothelial, gastric, and small bowel cancers
• Amsterdam Criteria II used for clinical diagnosis (see Classification section)
• Surveillance: Colonoscopy every 1-2 years from age 25

C. MYH-Associated Polyposis (MAP)

• Autosomal recessive (unlike most CRC syndromes which are dominant)
• Mutation in MUTYH (base excision repair gene)
• Produces attenuated polyposis (10-100 polyps)

D. Hamartomatous Polyposis Syndromes

• Peutz-Jeghers syndrome: STK11/LKB1 mutation; hamartomatous polyps throughout GI tract; mucocutaneous melanin pigmentation; increased risk of CRC and extra-colonic cancers
• Juvenile polyposis syndrome: SMAD4/BMPR1A mutation; juvenile hamartomatous polyps; increased risk of CRC and gastric cancer
• PTEN Hamartoma Tumour Syndrome (Cowden's): PTEN mutation; hamartomatous polyps; increased breast/thyroid/endometrial cancer risk

III. Familial CRC (non-hereditary, ~15-20%)

• First-degree relative with CRC: relative risk 2-3×
• Two first-degree relatives or one with young-onset (<50 years): risk 3-6×
• No identified genetic mutation but familial clustering
• Surveillance colonoscopy starts at age 40 or 10 years before the index case, whichever is earlier

IV. Pre-existing Disease

• Ulcerative colitis: Risk proportional to extent and duration; after 10 years of pancolitis risk is 0.5-1% per year; dysplasia-surveillance colonoscopy every 1-2 years
• Crohn's colitis: Lower but real increased risk (~4-7× compared to general population)
• Previous adenomatous polyps: Any adenoma confers increased risk; villous and high-grade dysplasia confers highest risk
• Previous CRC: 3-5% risk of synchronous second CRC; 5% risk of metachronous CRC

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E. PATHOGENESIS AND PATHOPHYSIOLOGY

The Adenoma-Carcinoma Sequence

1. Distribution of adenomas mirrors that of cancers (both 70% left-sided)
2. Larger adenomas are more likely to be dysplastic
3. The majority of early cancers have adjacent adenomatous tissue
4. Adenomas are found in one-third of specimens resected for CRC
5. Incidence of CRC falls with colonoscopy and polypectomy programmes

Microsatellite Instability (MSI) / Serrated Pathway

• Loss of MMR gene function → accumulation of mutations in repetitive DNA sequences (microsatellites)
• Produces "hypermutated" tumours
• MSI-high (MSI-H) tumours: typically right-sided, mucinous or poorly differentiated, higher immune infiltration, better prognosis per stage but paradoxically less responsive to 5-FU chemotherapy
• Clinically important: MSI-H/deficient MMR (dMMR) tumours respond dramatically to checkpoint inhibitors (pembrolizumab, nivolumab) - this is now tested routinely

• CMS1: MSI, immune activation (right-sided)
• CMS2: WNT and MYC activation (epithelial, left-sided)
• CMS3: Metabolic dysregulation
• CMS4: TGF-β activation, mesenchymal features, worst prognosis

Macroscopic Pathology

• Polypoid/exophytic: Projects into the lumen; more common in the caecum and right colon; bleed but rarely obstruct
• Annular/constricting ("napkin-ring"): Encircles the bowel; causes progressive luminal narrowing; most common in the left colon and sigmoid; typical "apple-core" appearance on barium enema
• Ulcerating: Raised, everted edges with central ulceration; commonest form; bleeds readily
• Diffusely infiltrating (linitis plastica-like): Rare; diffuse submucosal spread

Microscopic Pathology

• 95% are adenocarcinomas arising from glandular epithelium

• Well-differentiated (Grade 1): clear gland formation; best prognosis
• Moderately differentiated (Grade 2): some gland formation; most common
• Poorly differentiated (Grade 3): minimal glandular architecture; worst prognosis
• Mucinous adenocarcinoma (colloid type): >50% extracellular mucin; associated with MSI-H; ~15% of CRC
• Signet-ring cell carcinoma (<1%): Mucin displaces nucleus to periphery; very aggressive
• Medullary carcinoma: Sheets of cells with prominent lymphocytic infiltrate; strongly associated with MSI-H; good prognosis

Routes of Spread

1. Direct/local extension: Circumferential then transmural invasion; may invade adjacent organs (bladder, uterus, small bowel, ureter, sacrum)
2. Lymphatic: Follows orderly progression from epicolic → paracolic → intermediate → apical nodes; occasionally "skip metastases" occur
3. Haematogenous: Via portal vein to liver (most common site; one-third have liver metastases at diagnosis; 50% develop at some point); then lungs (second most common); less commonly brain, bone, adrenal, ovaries
4. Transcoelomicperitoneal seeding: Tumour cells implant on peritoneal surfaces and omentum → peritoneal carcinomatosis with malignant ascites; ovarian metastases (Krukenberg tumour)
5. Implantation: Rare; tumour cells may implant at suture lines or anastomoses, haemorrhoidectomy wounds, stoma sites

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F. CLASSIFICATION

I. Classification of Colorectal Polyps

• Villous histology (tubular 5% malignancy risk, tubulovillous 22%, villous 40%)
• Size >1 cm
• High-grade dysplasia
• Multiple adenomas (>3)

II. Macroscopic Polyp Classification

• Type I (Protruding): Ip (pedunculated), Is (sessile)
• Type II (Non-protruding, non-excavated): IIa (slightly elevated), IIb (flat), IIc (slightly depressed)
• Type III (Excavated/Ulcerated)

III. Dukes' Staging (Historical but still examined)

IV. TNM Staging (AJCC 8th Edition - Current Gold Standard)

V. Correlation Between Dukes' and TNM

VI. Amsterdam Criteria II for Lynch Syndrome

• One must be a first-degree relative of the other two
• At least two successive generations affected
• At least one diagnosed before age 50
• FAP excluded
• Tumour verified by pathology

VII. Revised Bethesda Guidelines (for MSI testing)

• CRC diagnosed under age 50
• Synchronous/metachronous CRC or Lynch-associated tumours regardless of age
• CRC with MSI-H histological features in patient <60 years
• CRC in ≥1 first-degree relative with Lynch-associated tumour; one diagnosed <50 years
• CRC in ≥2 first or second-degree relatives with Lynch-associated tumours regardless of age

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G. CLINICAL FEATURES

Symptoms

1. Change in Bowel Habit

• Right colon: Diarrhoea (loose stool from tumour mucus secretion; mass does not obstruct the wide lumen significantly)
• Left colon/sigmoid: Constipation, alternating constipation and diarrhoea, pencil-thin stools, tenesmus (feeling of incomplete evacuation)
• Important variation: Any change in bowel habit persisting >6 weeks in a person over 50 must be investigated as CRC until proven otherwise

2. Rectal Bleeding

• Right colon: Dark red or maroon blood mixed with stool; may be occult → iron deficiency anaemia without visible bleeding
• Left colon/rectum: Bright red blood on or mixed with stool (not always distinguishable from haemorrhoidal bleeding)
• Key point: Rectal bleeding should never be attributed to haemorrhoids without excluding CRC, especially in patients over 40 or with any change in bowel habit

3. Abdominal Pain

• Colicky pain (obstructive) vs. dull aching pain (direct invasion)
• Tumours of the right colon produce vague, right-sided discomfort
• Left colon tumours produce colicky left lower abdominal pain

4. Iron Deficiency Anaemia

• Fatigue, dyspnoea, pallor, palpitations
• Iron-deficiency anaemia in any man or postmenopausal woman must prompt colonoscopy to exclude right-sided CRC
• This is the classic "silent" presentation of caecal carcinoma

5. Weight Loss

• Anorexia and weight loss are ominous features suggesting advanced disease

6. Tenesmus

• Classic feature of rectal cancer; may cause frequent visits to the toilet passing only mucus ("spurious diarrhoea")

7. Mucus Discharge Per Rectum

• Villous tumours in the rectum can secrete copious amounts of mucus, potentially causing hypokalaemia (Villous Adenoma Syndrome: profuse watery diarrhoea, hypokalaemia, hyponatraemia - McKittrick-Wheelock syndrome in extreme cases)

Signs

Early

• Abdominal tenderness (non-specific)
• Positive faecal occult blood test (FOBT)

Late

• Palpable abdominal mass - firm, often mobile mass in right or left iliac fossa; caecal cancer most commonly presents as a palpable mass
• Hepatomegaly - from hepatic metastases (hard, irregular, nodular liver edge)
• Ascites - peritoneal carcinomatosis; shifting dullness and fluid thrill positive
• Palpable rectal mass on DRE - most rectal cancers (40%) are within reach of the examining finger; mass is hard, irregular, fixed or mobile
• Virchow's node (Troisier's sign) - left supraclavicular lymphadenopathy; indicates advanced disease with distant metastases
• Jaundice - extensive hepatic metastases
• Abdominal distension - intestinal obstruction (commoner in left-sided tumours)
• Cachectic appearance - advanced disease

Red Flag Features (demand urgent investigation)

• Rectal bleeding with change in bowel habit in any age
• Change in bowel habit persisting >6 weeks in patient over 40 (especially looser stools)
• Iron-deficiency anaemia in male or postmenopausal female
• Right iliac fossa mass
• Unexplained weight loss with bowel symptoms
• Tenesmus with rectal bleeding
• New-onset obstruction in patient over 50 (sigmoid carcinoma until proven otherwise)

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H. HISTORY TAKING

Presenting Complaint

• "When did you first notice a change in your bowel habit?"
• "Describe your normal bowel habit versus now"
• "Have you noticed any blood in your stools? Is it mixed in, on the surface, or on the paper? What colour is it?"
• "Have you had any abdominal pain? Is it colicky or constant? Where is it?"
• "Have you noticed any mucus in your stools?"
• "Do you feel as if you haven't completely emptied your bowel after opening it?" (tenesmus)
• "Have you lost any weight? How much and over what period?"
• "Have you noticed any tiredness, breathlessness, or pallor?" (anaemia)

Symptom Duration and Progression

• How long have symptoms been present?
• Are they progressive?
• Any acute episodes (obstruction, bleeding)?

Complication-Specific Questions

• "Have you had any episodes of abdominal distension/obstruction?" (acute presentation)
• "Any urinary symptoms - frequency, haematuria, pneumaturia?" (bladder invasion with colovesical fistula)
• "Any vaginal discharge with faecal odour?" (colovaginal fistula)
• "Any bone pain?" (skeletal metastases)
• "Any persistent cough or breathlessness?" (lung metastases)

Risk Factor History

• "Have any close relatives had bowel cancer or polyps? At what age?"
• "Have you had a previous colonoscopy? Were any polyps removed?"
• "Do you have a history of inflammatory bowel disease?"
• "Have you had any previous cancers?" (Lynch syndrome - associated extra-colonic cancers)
• "What is your diet like? Red meat, alcohol, fibre intake?"
• "Do you smoke?"
• "Are you on any regular medications?" (NSAIDs, aspirin are protective; immunosuppressants increase risk)
• "Have you ever had a stool test for blood?" (screening)

Differentiating Mimics

• "Do you have a history of haemorrhoids? Have they been confirmed by a doctor?" (versus rectal cancer)
• "Have you had any episodes of bloody diarrhoea with mucus, urgency, and cramping pain?" (inflammatory bowel disease)
• "Any symptoms of irritable bowel syndrome (cramping, bloating, relief with defaecation)?"
• "Any recent travel or change in diet?" (infective gastroenteritis)

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I. PHYSICAL EXAMINATION

General Examination

• General appearance: pallor (anaemia), cachexia, jaundice (hepatic metastases)
• Vital signs: heart rate (tachycardia if anaemia), blood pressure, temperature (if obstructed/infected)
• Hands: clubbing (rare), leukonychia, koilonychia (iron deficiency)
• Eyes: jaundice (scleral icterus), pallor (conjunctival pallor)
• Lymph nodes: Virchow's node (left supraclavicular - Troisier's sign)
• Face/skin: spider naevi (hepatic disease), flushing (carcinoid); perioral pigmentation (Peutz-Jeghers)

Abdominal Examination

Inspection

• Abdominal distension (obstruction)
• Visible peristalsis (obstruction)
• Previous surgical scars (prior colostomy, previous resection)
• Stoma presence
• Visible mass (rarely visible)

Palpation

• Superficial palpation: tenderness, guarding, rigidity (if perforated)
• Deep palpation: systematic examination of all quadrants
  • Right iliac fossa mass: hard, mobile, non-tender → caecal carcinoma
  • Left iliac fossa mass: sigmoid carcinoma or diverticular mass
  • Hepatomegaly: irregular, hard, nodular margin → metastatic deposits
  • Epigastric mass: omental or peritoneal deposits
• Check for inguinal lymphadenopathy (anal/rectal carcinoma)

Percussion

• Tympanism over distended bowel loops
• Shifting dullness (ascites from peritoneal carcinomatosis)
• Dullness over liver enlargement
• Absence of liver dullness (perforation - free air under diaphragm)

Auscultation

• High-pitched bowel sounds + borborygmi (partial obstruction)
• Absent bowel sounds (paralytic ileus after perforation)

Digital Rectal Examination (DRE) - ESSENTIAL

1. Inspect the perineum and anal verge (fistula, fissure, external haemorrhoids, prolapse)
2. Palpate: feel for a mass - note position (anterior/posterior/lateral), consistency (hard, irregular), fixity, surface, distance from anal verge
3. Assess sphincter tone
4. Withdraw finger: examine glove for blood, mucus, or slough
5. Note whether the prostate or cervix is separately palpable (distinguishes from rectal mass)

• Hard, irregular, craggy mass
• Typically fixed (advanced) or mobile (early)
• Blood on examining glove
• Mucus or slough on glove

• Height from anal verge (determines type of surgery)
• Mobility/fixity (indicates stage)
• Relationship to sphincters (determines continence preservation)

Proctoscopy and Rigid Sigmoidoscopy

• Proctoscope (examination of lower 8 cm): anal canal, haemorrhoids
• Rigid sigmoidoscope (15-20 cm): lower rectum; allows biopsy; preferred over flexible for assessing rectal tumour height
• Note exact distance of tumour from anal verge and from the dentate line

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J. DIFFERENTIAL DIAGNOSIS

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K. INVESTIGATIONS

1. Bedside

• Digital rectal examination (DRE): Detects up to 40% of rectal cancers; assesses mobility, relationship to sphincters; blood or mucus on glove
• Faecal Occult Blood Test (FOBT):
  • Guaiac-based FOBT (gFOBT): detects haem iron in stool; used for population screening; 3 samples from different bowel movements; 50-70% sensitivity for CRC
  • Faecal Immunochemical Test (FIT): uses antibodies to human globin; more sensitive (79%) and specific than gFOBT; now preferred for population screening (replaces gFOBT in UK NHS Bowel Cancer Screening Programme)
  • Positive test mandates colonoscopy
• Urinalysis: Pneumaturia (air in urine) or faecaluria suggests colovesical fistula

2. Laboratory

3. Imaging

4. Endoscopy

5. Histopathology

• Endoscopic biopsy: Establishes definitive tissue diagnosis; identifies histological type, grade, and MMR/MSI status
• Polypectomy specimen: Assess for villous features, grade of dysplasia, depth of invasion (if sessile), adequacy of excision margin
• Resection specimen: Dukes'/TNM stage; number of lymph nodes (minimum 12); circumferential resection margin (CRM); extramural vascular invasion (EMVI); differentiation grade; lymphocytic infiltration; MSI status; budding

6. Special Investigations

• KRAS/NRAS/BRAF mutation analysis: Essential before anti-EGFR therapy
• HER2 amplification testing: Emerging targeted therapy target
• NTRK fusion testing: Rare but highly actionable mutation
• Germline genetic testing: For Lynch syndrome (MLH1, MSH2, MSH6, PMS2); FAP (APC gene); MAP (MUTYH)
• Urinary 5-HIAA (5-hydroxyindoleacetic acid): If carcinoid tumour suspected (alongside serum chromogranin A)
• Cystoscopy: If colovesical fistula suspected
• Mesenteric angiography: If haematogenous bleeding requiring localisation (now largely replaced by CT angiography)

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L. MANAGEMENT

1. Initial Assessment and Management

• Full history and examination including DRE
• Urgent referral pathway (2-week rule) for suspected CRC
• Initial bloods: FBC, LFTs, CEA, U&E, coagulation, group and save
• CT chest/abdomen/pelvis for staging
• Colonoscopy and biopsy for tissue diagnosis
• Rectal cancer: MRI pelvis mandatory
• Discuss at Colorectal Multidisciplinary Team (MDT) meeting before treatment

• ABC approach
• IV access (large bore × 2), IV fluids
• Urinary catheter (monitor urine output)
• Bloods: FBC, U&E, LFTs, coagulation, G&S, lactate
• Erect chest X-ray and plain abdominal X-ray
• CT abdomen with contrast (diagnosis + staging simultaneously)
• NBM, nasogastric tube if vomiting
• IV antibiotics (broad spectrum) if peritonitis/perforation suspected
• Analgesia
• Anaesthetic/surgical team review

2. Resuscitation

• IV crystalloid resuscitation (Normal Saline or Hartmann's; 500 mL bolus; reassess)
• Correct electrolyte abnormalities (hypokalaemia from mucus secretion)
• Correct anaemia (transfuse if Hb <7 g/dL or symptomatic)
• Correct coagulopathy
• Optimise cardiovascular and respiratory status preoperatively
• Nutrition: if significantly malnourished, preoperative nutritional support (2-4 weeks oral supplements; rarely nasojejunal/parenteral feeding required)

3. Conservative Management

• "Watch and wait" for rectal cancer after complete clinical response to neoadjuvant CRT: ~20% of patients treated with long-course chemoradiotherapy achieve a complete clinical response (no residual tumour on MRI, endoscopy, or DRE). These patients may be managed with intensive surveillance (clinical examination, MRI, colonoscopy every 3 months for 2 years) without immediate surgery. "Watch and wait" is an option discussed in selected cases at specialist centres. Bailey & Love notes this option is available for the "20% who have a complete clinical response to neoadjuvant chemoradiotherapy."
• Palliative colonic stenting: For patients with obstructed left-sided CRC who are unfit for immediate surgery or who have metastatic disease; as a "bridge to surgery" to allow decompression and elective (rather than emergency) resection

4. Medical Treatment

Neoadjuvant Therapy (before surgery - for rectal cancer)

• Short-course radiotherapy (SCRT): 25 Gy in 5 fractions over 1 week, followed by surgery within 1 week or after 4-8 weeks (Stockholm III trial); reduces local recurrence rate; suitable for resectable T3 rectal cancer
• Long-course chemoradiotherapy (LCCRT): 45-50.4 Gy over 5-6 weeks with concurrent capecitabine or 5-FU; allows significant tumour downstaging; interval of 8-12 weeks before surgery; used for threatened/involved CRM or T4 rectal cancer

Adjuvant Chemotherapy (after surgery)

• Stage III (node-positive): Adjuvant chemotherapy reduces mortality by ~25%; standard regimen is CAPOX (capecitabine + oxaliplatin) for 3-6 months OR FOLFOX (5-FU, leucovorin, oxaliplatin)
• Stage II (high-risk): Adjuvant chemotherapy for high-risk Stage II features: T4, perforation, obstruction, inadequate lymph node harvest (<12 nodes), poor differentiation, lymphovascular/perineural invasion; MSI-H Stage II does NOT benefit from 5-FU
• Stage I: No adjuvant chemotherapy required

• Adjuvant chemotherapy (CAPOX or FOLFOX) given after surgery in locally advanced disease

Targeted and Immunotherapy

• Anti-EGFR therapy (cetuximab, panitumumab): Only in KRAS/NRAS/BRAF wild-type metastatic CRC; given with chemotherapy; KRAS-mutated tumours are resistant
• Anti-VEGF therapy (bevacizumab): Added to chemotherapy backbone in metastatic CRC regardless of KRAS status; inhibits angiogenesis
• Checkpoint inhibitors (pembrolizumab, nivolumab): For MSI-H/dMMR metastatic CRC; pembrolizumab approved as first-line in metastatic MSI-H CRC (KEYNOTE-177 trial); excellent response rates
• BRAF-targeted therapy (encorafenib + cetuximab): For BRAF V600E-mutated metastatic CRC (BEACON-CRC trial)

5. Surgical Treatment

PRINCIPLES OF SURGICAL RESECTION

1. En bloc resection of the tumour with adequate margins (≥5 cm proximal and distal for colon; ≥2 cm distal for rectal cancer)
2. High ligation of the named feeding vessel at its origin (to include all draining lymph nodes)
3. Minimum 12 lymph nodes harvested for adequate staging
4. Circumferential Resection Margin (CRM) ≥1 mm (negative CRM is essential; positive CRM is main predictor of local recurrence)
5. No-touch isolation technique (ligate vessels before mobilising tumour) - reduces tumour cell dissemination
6. Total Mesorectal Excision (TME) for rectal cancer - sharp dissection in the "holy plane" preserving intact mesorectum; reduces local recurrence from 30-40% to <5%

Elective Resections for Colon Cancer

• For caecal, appendiceal, ascending colon, and hepatic flexure tumours
• Removes caecum, ascending colon, hepatic flexure, right 1/3 transverse colon with their mesentery
• High ligation of ileocolic, right colic, and right branch of middle colic arteries
• Reconstruction: ileotransverse anastomosis
• Extended right hemicolectomy: For transverse colon tumours; additionally removes the middle colic artery territory

• For descending colon tumours
• Removes descending colon with its mesentery
• High ligation of left colic artery (IMA preserved if possible) or IMA at origin
• Reconstruction: colo-colic anastomosis

• For sigmoid colon tumours
• High ligation of sigmoid branches of IMA
• Reconstruction: descendo-rectal anastomosis

• For multiple synchronous cancers, FAP, emergency total colonic obstruction
• Removes entire colon; reconstruction: ileostomy or ileorectal anastomosis

Elective Resections for Rectal Cancer (Bailey & Love, 28th ed.)

• Tumours of the upper rectum (>10 cm from anal verge)
• TME performed down to 5 cm below the tumour
• Colorectal anastomosis performed above the peritoneal reflection
• Defunctioning loop ileostomy not always required

• Tumours of the mid and lower rectum (5-10 cm from anal verge)
• Complete TME to the pelvic floor
• Circular stapling device used for colorectal or coloanal anastomosis
• "Double stapling technique" allows very low anastomoses (Figure 79.23, Bailey & Love)
• Colonic J-pouch or transverse coloplasty may be fashioned to improve function by increasing reservoir capacity
• Defunctioning loop ileostomy (temporary) is recommended to protect the anastomosis; closed after 6-8 weeks

• Tumours of the distal rectum (<4-5 cm from anal verge) involving the sphincter complex; tumours where sphincter preservation is not possible without compromising oncological clearance
• Combined abdominal and perineal dissection removing the entire rectum, anal canal, and sphincter complex en bloc
• Results in a permanent end colostomy (left iliac fossa)
• Perineal wound may be closed primarily or with myocutaneous flap (after ELAPE - extralevator APR)
• ELAPE (Extralevator APR): Modified technique with wider perineal dissection outside the levator ani muscles; reduces risk of positive CRM ("waist" effect)

• Emergency resection for obstructed or perforated left-sided/sigmoid/rectal cancer when primary anastomosis is unsafe
• Tumour resected; proximal end brought out as end colostomy; distal rectal stump left as a "Hartmann's pouch"
• Stoma may be reversed later (Hartmann's reversal) in fit patients

• Local excision for selected early rectal cancers (T1 and selected T2 with no high-risk features)
• Full-thickness rectal wall excision with clear margins
• Principle: avoids radical surgery and colostomy in selected early-stage tumours
• Risk: no nodal clearance; lymph node metastasis risk ~10% for T1; higher for T2

• Minimally invasive approaches now standard for elective colorectal resection
• Equivalent oncological outcomes to open surgery (CLASSIC trial for colon, CLASICC trial for rectum)
• Advantages: less pain, earlier recovery, shorter hospital stay, less blood loss
• Disadvantages: longer operative time initially; steep learning curve; high conversion rate for rectal cancer (converted to open in ~15%)
• Robotic surgery: Offers 3D vision and articulated instruments; particular advantage in narrow pelvis for rectal dissection

Emergency Surgery (Obstruction/Perforation)

1. Hartmann's procedure (safest in emergency setting)
2. On-table colonic lavage + primary anastomosis ± defunctioning loop ileostomy
3. Subtotal colectomy with primary ileostomy or ileorectal anastomosis
4. Colonic stent as bridge to elective surgery (avoids emergency surgery; allows staging; reduces stoma rates)

• Emergency laparotomy
• Hartmann's procedure or primary resection with anastomosis (more complex; less safe in contaminated field)
• Peritoneal lavage
• IV antibiotics

Surgery for Metastatic Disease

• Liver resection (hepatectomy): In carefully selected patients with resectable liver-only or predominantly liver metastases, curative hepatic resection achieves 5-year survival of 25-40%. Requirements: adequate residual liver volume (future liver remnant >30%); no extrahepatic disease (or limited controllable extrahepatic disease); fit patient; requires input from hepatobiliary surgical team at MDT
• Portal vein embolisation (PVE): Before major hepatectomy if future liver remnant is insufficient; induces hypertrophy of the contralateral lobe over 4-6 weeks
• Ablative techniques: Radiofrequency ablation (RFA), microwave ablation (MWA) for unresectable liver metastases in fit patients
• HIPEC (Hyperthermic Intraperitoneal Chemotherapy): At time of cytoreductive surgery for selected peritoneal carcinomatosis; delivers concentrated intraperitoneal chemotherapy (usually oxaliplatin or mitomycin C) at hyperthermic temperatures; highly selected patients; major morbidity
• Lung resection: For selected pulmonary metastases; 5-year survival ~40% in resected cases

Surgery for Hereditary CRC

1. Total proctocolectomy with end (Brooke) ileostomy: Removes all colorectal mucosa; no cancer risk; permanent stoma
2. Total abdominal colectomy with ileorectal anastomosis (IRA): Preserves continence; requires lifelong rectal surveillance; risk of rectal cancer in retained rectum
3. Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) ± loop ileostomy: Gold standard for most FAP patients; removes all colorectal mucosa; maintains continence via ileal J-pouch; ~50% experience some degree of incontinence; risk of pouch adenomas in transition zone

• Mucosectomy at time of IPAA reduces but does not eliminate cancer risk in the anal transition zone

6. Postoperative Care

• Enhanced Recovery After Surgery (ERAS) protocol (Bailey & Love, Summary Box 77.7):
  • Preadmission counselling
  • Preoperative carbohydrate loading (prevents insulin resistance)
  • Avoidance of preoperative dehydration
  • Avoidance of nasogastric tubes (unless indicated)
  • Short/transverse incisions or laparoscopic procedure
  • Avoidance of perioperative fluid/salt overload
  • Avoidance of opiate analgesia (epidural/TAP block preferred)
  • Maintenance of perioperative temperature (normothermia)
  • Prevention of postoperative nausea and vomiting
  • Early mobilisation (within 24 hours)
  • Early introduction of oral fluids/diet
• Target: hospital discharge 3-5 days (laparoscopic); 5-7 days (open)

• Preoperative stoma siting by enterostomal therapist
• Stoma nurse education and follow-up
• Psychosocial support (significant adjustment required)

• Watch for anastomotic leak (Day 3-7 most common): fever, tachycardia, peritonism, high drain output with faeculent fluid, ileus beyond Day 3
• CT with rectal contrast if suspected

• Anticoagulation (LMWH) + TED stockings for 28 days post colorectal cancer surgery

7. Rehabilitation and Follow-up

• CEA: every 3-6 months for 3 years, then annually for 2 years
• CT chest/abdomen/pelvis: at 12 and 24 months (to detect resectable recurrence)
• Colonoscopy: at 1 year post-resection (check anastomosis + exclude new polyps); then every 3-5 years if clear
• DRE + proctoscopy: 3-6 monthly for 2-3 years for rectal cancer

• Defunctioning loop ileostomy reversed after 6-8 weeks (confirm anastomotic integrity first with water-soluble contrast enema)

• After low anterior resection: "Low anterior resection syndrome (LARS)" - urgency, frequency, clustering of defaecation; managed with dietary modification, bulking agents, antidiarrhoeal agents, biofeedback
• After total proctocolectomy with IPAA: Average 4-8 stools per day; pouchitis (treated with metronidazole/ciprofloxacin)

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M. SURGICAL PROCEDURES

1. Right Hemicolectomy

1. Midline laparotomy or 4-5 laparoscopic ports
2. Mobilise right colon by incising lateral peritoneal reflection (white line of Toldt)
3. Identify and protect ureter and gonadal vessels
4. High ligation of ileocolic and right colic vessels at their origins from the SMA
5. Divide ileum 10 cm proximal to caecum (in non-cancer cases) or further (cancer)
6. Divide transverse colon at mid-point
7. Specimen removed
8. Ileocolic anastomosis (functional end-to-end using stapler or hand-sewn)

2. Anterior Resection (Low Anterior Resection - LAR)

1. Laparotomy (midline) or laparoscopic/robotic approach; Lloyd-Davies (lithotomy-Trendelenburg) position
2. High ligation of IMA at origin (or just distal to left colic artery origin to preserve blood supply)
3. Mobilise descending and sigmoid colon
4. Enter "holy plane" of TME - sharp dissection anterior to Waldeyer's fascia, posterior to mesorectal fascia, medial to the lateral ligaments, anterior to Denonvilliers' fascia
5. Preservation of pelvic autonomic nerves (hypogastric nerves, pelvic splanchnic nerves)
6. Divide rectum distally with transverse stapler (TA stapler) at appropriate level
7. Specimen removed
8. Colorectal or coloanal anastomosis using circular stapling device (EEA stapler) - "double-stapling technique"
9. Air leak test (fill pelvis with saline; inflate bowel with air per rectum; watch for bubbles)
10. Defunctioning loop ileostomy fashioned in right iliac fossa

3. Abdominoperineal Resection (APR / Miles' Operation)

• Distal rectal cancer (<4-5 cm from anal verge) involving or threatening the sphincter mechanism
• Low rectal cancer with poor sphincter function preoperatively
• Recurrent rectal cancer after previous anterior resection

1. Patient in Lloyd-Davies position (allows synchronous abdominal and perineal access)
2. Abdominal phase: high IMA ligation, mobilisation of colon, and complete TME
3. Sigmoid and descending colon are brought through the left iliac fossa as a permanent end colostomy
4. Perineal phase: patient repositioned or approached simultaneously by second team
5. Elliptical incision around the anus; wide excision of ischiorectal fossa fat
6. ELAPE: excision carried outside the levators (reduces positive CRM - the "waist" created by standard APR)
7. Perineal wound closure (primary if clean; myocutaneous flap if post-irradiation or ELAPE)
8. Abdominal closure; stoma fashioned

• Intraoperative: bleeding (presacral venous plexus), ureteric injury, small bowel injury, bladder injury
• Early: wound infection, perineal dehiscence (especially after radiotherapy), urinary retention
• Late: phantom rectum sensation, perineal hernia, stoma complications (retraction, prolapse, parastomal hernia)

4. Total Mesorectal Excision (TME)

• Before TME was introduced by Heald in 1982, local recurrence after rectal surgery was 30-40%
• With quality TME, local recurrence is <5%
• The intact mesorectal envelope ensures all perirectal lymph nodes are removed
• CRM involvement is the strongest predictor of local recurrence

• Waldeyer's fascia: Presacral fascia posteriorly
• Denonvilliers' fascia: Between rectum and prostate/vagina anteriorly
• Lateral ligaments: Condensations of connective tissue lateral to the rectum containing middle rectal vessels
• "Holy plane": The avascular plane of TME; violation causes bleeding and risk to autonomic nerves

5. Hartmann's Procedure

1. Emergency midline laparotomy
2. Identify and resect the tumour with appropriate margins
3. Close the distal rectal/sigmoid stump (Hartmann's pouch)
4. Bring the proximal end out as an end colostomy in the left iliac fossa
5. Peritoneal lavage if perforation
6. Closure

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N. COMPLICATIONS

Early Complications (within 30 days of surgery)

Intermediate Complications (2-12 weeks)

Late Complications

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O. PROGNOSIS

Overall Survival by Stage

Favourable Prognostic Factors

• Early stage (T1/T2, N0)
• Well-differentiated histology (Grade 1)
• MSI-H/dMMR status (paradoxically better prognosis per stage despite more aggressive histological appearance - more immune infiltration)
• Significant lymphocytic infiltration (tumour-infiltrating lymphocytes)
• Fibrotic stromal reaction (Pye's: greater fibrosis = worse outlook - note this is controversial)
• Negative CRM (>1 mm)
• Adequate lymph node harvest (≥12 nodes)
• Complete (R0) resection
• Absence of extramural vascular invasion (EMVI)
• Complete response to neoadjuvant therapy

Unfavourable Prognostic Factors

• Advanced stage (T4, N2, M1)
• Poorly differentiated (Grade 3) or mucinous/signet-ring cell histology
• Microsatellite stable (MSS) - less immune infiltration
• Positive CRM (the single most important predictor of local recurrence in rectal cancer)
• BRAF V600E mutation (associated with MSS tumours; worst prognosis in metastatic disease)
• Emergency presentation (obstruction/perforation)
• High preoperative CEA
• Extramural vascular invasion (EMVI)
• Peritoneal involvement (M1c)
• Poor nutritional status
• Male sex (for rectal cancer)
• High ASA grade (comorbidities)

Quality of Life Considerations

• Permanent stoma (APR) has profound psychological impact; proper stoma support is essential
• LARS significantly affects quality of life after LAR; recovery may take 1-2 years
• Sexual dysfunction is common after pelvic surgery and must be discussed preoperatively
• Chemotherapy toxicity (peripheral neuropathy with oxaliplatin; diarrhoea with capecitabine)

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P. EXAMINATION PEARLS

Common MBBS Essay Questions

1. "Classify colorectal neoplasms. Describe the adenoma-carcinoma sequence."
2. "Describe the clinical features, investigations, and surgical management of carcinoma of the colon."
3. "What is total mesorectal excision (TME)? Why is it the standard of care for rectal cancer?"
4. "Compare and contrast anterior resection with abdominoperineal resection for carcinoma of the rectum."
5. "Describe the staging of colorectal cancer using the Dukes' and TNM systems."
6. "Outline the management of a 60-year-old man presenting with acute large bowel obstruction."
7. "What are the hereditary colorectal cancer syndromes? How are they managed?"

Viva Questions and Answers

OSCE Points

• Always perform a DRE in any patient with rectal symptoms - never omit it
• Describe a rectal mass by: position (anterior/posterior/lateral); consistency; surface (smooth/irregular/craggy); mobility; distance from anal verge
• State that rigid sigmoidoscopy gives the most accurate measurement of tumour height
• Always check Virchow's node (left supraclavicular) in a patient with suspected GI malignancy
• For any rectal bleeding, do not attribute to haemorrhoids without excluding CRC
• Remember to check for signs of metastatic disease: hepatomegaly, ascites, supraclavicular lymphadenopathy, pallor

High-Yield Memory Aids

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Q. CLINICAL REASONING

How a Clinician Approaches Suspected CRC

• Right colon: elderly patient, iron-deficiency anaemia, RIF mass → caecal carcinoma
• Left colon: change in bowel habit + blood in stool + colicky pain → left CRC
• Rectum: tenesmus + fresh rectal bleeding + mucus → rectal cancer
• Emergency: acute large bowel obstruction in patient >50 → sigmoid carcinoma until proven otherwise

• Rectal bleeding + change in bowel habit in any adult
• Iron-deficiency anaemia in male or postmenopausal female
• Palpable RIF mass
• Any new large bowel obstruction in patient over 50

• Colonoscopy + biopsy = gold standard for diagnosis

• CT chest/abdomen/pelvis (systemic staging)
• MRI pelvis (local staging for rectal cancer)
• CEA baseline

• Curative vs. palliative intent based on staging
• Neoadjuvant therapy if indicated (rectal cancer with threatened CRM or T4)
• Operative planning (type of resection, stoma requirement)
• Adjuvant therapy planning

Investigation Algorithm

Suspected CRC
      ↓
FBC + CEA + LFTs + U&E
      ↓
Colonoscopy + Biopsy
      ↓
CRC confirmed
      ↓
CT Chest/Abdomen/Pelvis (staging)
      ↓
      ├── COLON CANCER:
      │   Surgical resection ± adjuvant chemotherapy
      │
      └── RECTAL CANCER:
          MRI Pelvis (local staging)
               ↓
      ┌─────────────────────────────────────────┐
      │              │                          │
  CRM clear       CRM threatened          T4 / Low tumour
  (>1mm)          (<1mm); T3              threatening sphincter
      │              │                          │
  Direct          Neoadjuvant               Long-course CRT
  Surgery         SCRT or LCCRT             + assessment for
  (TME)           then TME                  sphincter preservation
                                            or APR

Management Algorithm

CRC diagnosed and staged
         ↓
    Resectable?
    /         \
  YES          NO
   ↓             ↓
Curative     Metastatic/unresectable
intent       ↓
   ↓         Systemic chemotherapy
Elective     + targeted therapy
surgery      ± palliative surgery
   ↓         (stenting, diversion)
  R0 resection?
  /          \
YES           NO (R1 or R2)
  ↓              ↓
Adjuvant     Chemotherapy
chemo if     ± palliative
Stage III    radiotherapy
or high-
risk Stage II
   ↓
Surveillance:
CEA 3-6 monthly
CT at 12 + 24 months
Colonoscopy at 1 year

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R. SUMMARY TABLES

Table 1: Classification of Colorectal Polyps

Table 2: Dukes' Staging vs TNM vs Survival

Table 3: Comparison of Anterior Resection vs APR

Table 4: Hereditary CRC Syndromes

Table 5: Investigation Summary Table

Table 6: Systemic Treatment Summary

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S. RAPID REVISION SECTION

Top 20 Facts to Remember

1. CRC is the second most common cause of cancer death in non-smokers in Western countries (Bailey & Love)
2. 50% of CRC occur in the sigmoid colon and rectum
3. The adenoma-carcinoma sequence takes 10-15 years: APC → K-RAS → DCC/SMAD4 → TP53
4. Dukes' staging: A = 95%, B = 68%, C = 34%, D = <10% 5-year survival
5. FAP: APC gene mutation (chromosome 5q); 100% lifetime CRC risk; treated by prophylactic colectomy
6. Lynch syndrome: MMR gene mutations (MLH1/MSH2/MSH6/PMS2); MSI; right-sided CRC; associated endometrial/ovarian/urothelial cancer
7. Right-sided CRC: Iron-deficiency anaemia (occult bleeding) + RIF mass; rarely obstructs
8. Left-sided CRC: Change in bowel habit + visible blood + obstruction (narrow lumen + solid stool)
9. Rectal cancer: Tenesmus + mucus + rectal bleeding; diagnosed by DRE + rigid sigmoidoscopy + colonoscopy
10. MRI pelvis = gold standard local staging for rectal cancer; determines CRM status and need for neoadjuvant therapy
11. CRM (Circumferential Resection Margin) = single most important predictor of local recurrence in rectal cancer
12. TME (Total Mesorectal Excision) reduces local recurrence from 30-40% to <5%; "holy plane" dissection
13. APR (Miles' operation) = permanent colostomy; for tumours <4-5 cm from anal verge involving sphincters
14. Minimum 12 lymph nodes must be harvested for adequate staging
15. CEA: Not diagnostic; used for baseline and postoperative recurrence surveillance
16. KRAS mutation = resistant to anti-EGFR therapy (cetuximab/panitumumab); must test before prescribing
17. MSI-H/dMMR CRC responds to checkpoint inhibitors (pembrolizumab); first-line in metastatic MSI-H CRC
18. Liver metastases (33% at diagnosis; 50% develop eventually) = most common site; resection achieves 25-40% 5-year survival in selected cases
19. LARS (Low Anterior Resection Syndrome) = urgency, frequency, clustering, incontinence after LAR; must counsel patients preoperatively
20. FIT (Faecal Immunochemical Test) = now preferred population screening tool; positive test mandates colonoscopy

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One-Page Revision Summary

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Viva Quick Review

• Most common histological type of CRC? Adenocarcinoma (columnar cell; >95%)
• Most common site of distant metastasis? Liver (via portal vein)
• Gene mutated in FAP? APC (chromosome 5q21)
• Genes mutated in Lynch syndrome? MLH1, MSH2, MSH6, PMS2
• What is CHRPE? Congenital hypertrophy of retinal pigment epithelium - marker for FAP
• Best investigation for local staging of rectal cancer? MRI pelvis
• What is TME? Total mesorectal excision - sharp dissection in holy plane removing intact mesorectum
• Most important predictor of local recurrence in rectal cancer? Positive CRM
• Minimum lymph nodes for staging? 12 nodes
• When is APR indicated? Tumours <4-5 cm from anal verge involving/threatening sphincters
• What is "watch and wait"? Non-operative management for complete clinical responders to CRT (~20%)
• Why avoid anti-EGFR therapy in KRAS-mutant CRC? Downstream RAS activation bypasses EGFR; therapy is ineffective
• Which CRC patients benefit from immunotherapy? MSI-H/dMMR tumours (pembrolizumab)
• Survival after hepatic resection for metastases? 25-40% at 5 years in selected patients
• What is LARS? Low Anterior Resection Syndrome - urgency, frequency, clustering, incontinence; managed conservatively

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T. REFERENCES USED

Primary Sources

Agreement Among Sources

• Adenoma-carcinoma sequence as the dominant carcinogenesis model
• TNM staging as the international standard; Dukes' as a historical/supplementary system
• TME as the gold standard technique for rectal cancer surgery
• The critical importance of the CRM in rectal cancer outcomes
• Colonoscopy as the gold standard diagnostic and surveillance tool
• MSI testing and KRAS testing as essential for guiding therapy

Areas of Variation

• Dukes' staging: Bailey & Love and Pye's use Dukes' extensively as it remains commonly tested; Schwartz's and Sabiston focus on TNM (AJCC)
• Exact survival figures: Minor variation between sources (e.g., Dukes' C survival quoted as 34% in Pye's; 40-65% in TNM-based Stage III data from Schwartz's due to N substaging)
• Neoadjuvant therapy protocols: Newer evidence (not fully reflected in older editions) now supports SCRT as equivalent to LCCRT for some tumours; more recent sources reflect updated trial data
• "Watch and wait": Bailey & Love (28th ed.) acknowledges this as an evolving option (~20% of complete responders); not addressed in older Schwartz's editions
• CMS subtypes: Bailey & Love (28th ed.) discusses CMS1-4 molecular subtypes; this represents newer evidence not in older textbook editions

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What This Note Contains