Colorectal Carcinoma: Long Case Examination Q&A

1. What is colorectal carcinoma?

2. What are the important risk factors?

• Increasing age
• Previous adenomatous polyps or colorectal cancer
• Family history of colorectal cancer
• Lynch syndrome
• Familial adenomatous polyposis (FAP)
• Long-standing ulcerative colitis or Crohn colitis
• Diet high in red/processed meat, obesity, smoking, alcohol, physical inactivity
• Type 2 diabetes

3. What are the common sites of colorectal carcinoma?

• Rectosigmoid region
• Caecum and ascending colon
• Descending colon
• Rectum

4. How do right-sided and left-sided colonic cancers differ clinically?

5. What are the presenting symptoms?

• Rectal bleeding or blood mixed with stool
• Change in bowel habits, especially new constipation/diarrhoea
• Tenesmus, urgency, or mucus discharge in rectal cancer
• Abdominal pain or colic
• Features of intestinal obstruction
• Unexplained iron-deficiency anaemia
• Weight loss, anorexia, fatigue
• Palpable abdominal mass
• Metastatic symptoms: hepatomegaly, jaundice, ascites, cough, bone pain

6. How would you take the history in a patient with suspected colorectal cancer?

1. Bleeding: onset, quantity, blood mixed with stool or on paper, melena.
2. Bowel habit: constipation, diarrhoea, alternating bowel habit, narrowing of stool calibre.
3. Obstructive symptoms: colicky pain, distension, vomiting, obstipation.
4. Rectal symptoms: tenesmus, urgency, mucus, painful defecation, incontinence.
5. Constitutional symptoms: weight loss, anorexia, fever, fatigue.
6. Symptoms of metastases: jaundice, abdominal fullness, respiratory symptoms, bone pain, neurological symptoms.
7. Past history: polyps, inflammatory bowel disease, previous cancer or irradiation.
8. Family history: colorectal, endometrial, ovarian, gastric, pancreatic or urinary tract cancer.
9. Drug history: anticoagulants, antiplatelets, NSAIDs.
10. Functional status and comorbidity: cardiopulmonary disease, diabetes, renal disease, nutritional status.

7. What will you look for on examination?

• Pallor due to chronic blood loss
• Cachexia and weight loss
• Dehydration if obstruction is present
• Supraclavicular lymphadenopathy, especially left supraclavicular node
• Lower-limb oedema or deep-vein thrombosis

• Distension and visible peristalsis
• Palpable abdominal mass
• Hepatomegaly, nodular liver or ascites suggesting metastases
• Signs of intestinal obstruction or peritonitis

• Must be performed in every suspected colorectal cancer.
• Assess mass location, distance from anal verge, circumference involved, mobility/fixity, ulceration, bleeding, sphincter involvement, and relation to prostate/vagina.
• Examine stool on glove for blood.

• Proctoscopy/rigid sigmoidoscopy where appropriate.
• Examine groins, especially in very low rectal tumours or anal involvement.

8. Give an ideal long-case presentation.

“This is a ___-year-old patient with progressive alteration of bowel habits, rectal bleeding, weight loss and features suggestive of left-sided colorectal carcinoma. On examination, the patient has pallor, and abdominal examination reveals ___. Digital rectal examination reveals a proliferative rectal growth at ___ cm from the anal verge, involving ___ circumference, which is mobile/fixed.

My provisional diagnosis is colorectal carcinoma, likely involving the ___, with/without intestinal obstruction and with/without evidence of hepatic metastases. I would confirm the diagnosis histologically, perform local and distant staging, assess fitness for treatment, discuss the case in a multidisciplinary team meeting, and plan treatment according to site, stage, pathology and molecular profile.”

9. What are the important differential diagnoses?

• Adenomatous colorectal polyp
• Inflammatory bowel disease
• Diverticular disease or diverticular stricture
• Intestinal tuberculosis
• Ischaemic colitis or stricture
• Amoebic colitis
• Haemorrhoids or anal fissure in a patient with rectal bleeding
• Colorectal lymphoma
• Gynaecological malignancy invading rectum
• Benign rectal stricture

10. How will you confirm the diagnosis?

• Colonoscopy with biopsy is the investigation of choice.
• It confirms histology, defines the lesion, detects synchronous lesions, and permits biopsy.
• If complete colonoscopy is not possible due to obstruction, evaluate the remaining colon after surgery or with CT colonography where appropriate.

11. What baseline investigations will you order?

• Complete blood count: look for iron-deficiency anaemia
• Renal function, electrolytes
• Liver function tests
• Serum albumin and nutritional assessment
• Coagulation profile
• Blood grouping and cross-match
• Iron studies where appropriate
• Baseline CEA
• ECG, chest assessment, echocardiography or pulmonary testing according to fitness for surgery
• Colonoscopic biopsy for histopathology
• Mismatch repair (MMR) or microsatellite-instability testing

12. How will you stage colorectal carcinoma?

• Contrast-enhanced CT chest, abdomen and pelvis for metastatic staging.

• MRI pelvis for local staging, circumferential resection margin, sphincter/levator involvement and nodal assessment.
• CT chest, abdomen and pelvis for distant metastases.
• Endorectal ultrasound may help distinguish early T1 from T2 lesions.

13. State the TNM classification.

• Tis: carcinoma in situ
• T1: invades submucosa
• T2: invades muscularis propria
• T3: extends through muscularis propria into pericolorectal tissue
• T4a: penetrates visceral peritoneum
• T4b: invades or adheres to adjacent organs/structures

• N0: no regional nodal metastasis
• N1: 1-3 regional nodes involved or tumour deposits
• N2: 4 or more regional nodes involved

• M0: no distant metastasis
• M1: distant metastasis present

14. What are the stage groupings?

• Stage 0: Tis N0 M0
• Stage I: T1-2 N0 M0
• Stage II: T3-4 N0 M0
• Stage III: any T, N1-2, M0
• Stage IV: any T, any N, M1

15. What is the management of colon cancer by stage?

16. What is the principle of surgery for colon cancer?

• Adequate proximal and distal bowel margins
• En bloc removal of regional lymphatic drainage and mesocolon
• Vascular ligation appropriate to the tumour location
• Restoration of bowel continuity where safe
• Assessment for synchronous lesions and peritoneal/liver metastases

• Right hemicolectomy for caecal, ascending colon and proximal transverse lesions
• Extended right hemicolectomy for selected transverse-colon lesions
• Left hemicolectomy for descending-colon lesions
• Sigmoid colectomy for sigmoid cancer
• Subtotal colectomy in selected synchronous cancers, obstruction with caecal compromise, or hereditary syndromes

17. What makes Stage II colon cancer “high risk”?

• T4 tumour
• Bowel obstruction or perforation at presentation
• Inadequate lymph-node assessment
• Poorly differentiated histology, except some MSI-H tumours
• Lymphovascular or perineural invasion
• Positive or close resection margin
• Tumour budding

18. What is the management of rectal carcinoma?

• Very early favourable T1 lesion: local excision may be suitable in selected cases.
• Resectable upper/mid rectal cancer: anterior resection with total mesorectal excision.
• Low rectal tumour with sphincter preservation possible: low anterior resection or ultralow anterior resection with total mesorectal excision.
• Tumour involving sphincter/levator or where clear margins cannot be achieved: abdominoperineal resection with permanent colostomy.
• Locally advanced rectal cancer: neoadjuvant chemotherapy with radiation-based treatment, followed by total mesorectal excision in appropriate cases.

19. What is total mesorectal excision?

20. When is abdominoperineal resection indicated?

• Tumour invades external anal sphincter or levator ani
• Distal margin cannot be obtained with sphincter preservation
• Poor pre-existing sphincter function
• Very low fixed tumour where a safe restorative procedure is unsuitable

21. What is the role of neoadjuvant therapy in rectal cancer?

• Downstage the tumour
• Improve the chance of an R0 resection
• Reduce local recurrence
• Improve the feasibility of sphincter preservation in selected patients

22. What molecular tests should be performed?

• Mismatch repair deficiency (dMMR)/microsatellite instability (MSI-H)
• KRAS and NRAS mutations in metastatic disease
• BRAF V600E mutation
• HER2 amplification in selected metastatic cases
• NTRK fusion in selected cases

23. What is the role of CEA?

• Baseline measurement before treatment
• Prognostic assessment
• Monitoring response to treatment
• Detecting recurrence during follow-up

24. What are common sites of metastasis?

• Liver: most common, especially from colon cancers through portal circulation
• Lung: particularly frequent in rectal cancer
• Peritoneum
• Regional and distant lymph nodes
• Ovary, including Krukenberg tumour
• Bone and brain, less commonly

25. How do you manage an obstructing left-sided colon cancer?

• Emergency oncological resection with primary anastomosis in selected stable patients
• Hartmann procedure
• Diverting stoma
• Endoscopic self-expanding metal stent as palliation or bridge to surgery in selected cases
• Subtotal colectomy in selected situations, such as synchronous proximal pathology or caecal compromise

26. How do you manage perforated colorectal cancer?

• Immediate resuscitation and broad-spectrum antibiotics
• Urgent laparotomy
• Control contamination and sepsis
• Oncological resection if feasible
• Stoma formation is often safer than primary anastomosis in unstable or contaminated cases
• Postoperative staging and MDT review

27. What are postoperative complications?

• Bleeding
• Wound infection
• Chest infection
• Venous thromboembolism
• Urinary retention
• Ileus

• Anastomotic leak
• Intra-abdominal abscess
• Stoma complications
• Bowel obstruction due to adhesions
• Sexual and urinary dysfunction after rectal surgery
• Low anterior resection syndrome
• Local recurrence or metastatic recurrence

28. What follow-up is required after curative treatment?

• Clinical review and symptom assessment
• Periodic CEA measurement
• CT imaging in patients suitable for treatment of recurrence
• Colonoscopic surveillance, often at approximately 1 year after resection, then according to findings and local protocol
• Assessment of nutrition, stoma function, bowel dysfunction, sexual and urinary health, and psychosocial support

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