Topic Breakdown

1. Epidemiology & Etiology - incidence, risk factors (H. pylori, diet, smoking, genetics like CDH1/hereditary diffuse gastric cancer)
2. Pathology & Classification - Lauren classification (intestinal vs diffuse), Borrmann morphologic types, histology, early vs advanced gastric cancer
3. Clinical Features & Diagnosis - presentation, endoscopy/biopsy, EUS, CT/staging workup, TNM staging
4. Treatment Overview - endoscopic resection (EMR/ESD) for early cancer, perioperative/neoadjuvant chemotherapy, radiotherapy, targeted therapy (trastuzumab for HER2+), immunotherapy (checkpoint inhibitors), palliative options
5. Gastrectomy - Surgical Detail - total vs subtotal/distal gastrectomy, D1 vs D2 lymphadenectomy, reconstruction methods (Roux-en-Y, Billroth I/II), laparoscopic/robotic approaches, sleeve/proximal gastrectomy variants
6. Postoperative Complications & Management - anastomotic leak, dumping syndrome, nutritional deficiencies (B12, iron), bile reflux
7. Prognosis & Follow-up - survival by stage, surveillance

Brief Overview

Topic Breakdown

1. Epidemiology & Etiology - incidence, risk factors (H. pylori, diet, smoking, genetics like CDH1/hereditary diffuse gastric cancer)
2. Pathology & Classification - Lauren classification (intestinal vs diffuse), Borrmann morphologic types, histology, early vs advanced gastric cancer
3. Clinical Features & Diagnosis - presentation, endoscopy/biopsy, EUS, CT/staging workup, TNM staging
4. Treatment Overview - endoscopic resection (EMR/ESD) for early cancer, perioperative/neoadjuvant chemotherapy, radiotherapy, targeted therapy (trastuzumab for HER2+), immunotherapy (checkpoint inhibitors), palliative options
5. Gastrectomy - Surgical Detail - total vs subtotal/distal gastrectomy, D1 vs D2 lymphadenectomy, reconstruction methods (Roux-en-Y, Billroth I/II), laparoscopic/robotic approaches, sleeve/proximal gastrectomy variants
6. Postoperative Complications & Management - anastomotic leak, dumping syndrome, nutritional deficiencies (B12, iron), bile reflux
7. Prognosis & Follow-up - survival by stage, surveillance

Brief Overview

1. Pathology & staging (TNM, Lauren classification, Borrmann types)
2. Treatment overview (chemotherapy, targeted therapy, immunotherapy, radiotherapy)
3. Gastrectomy surgical technique in detail (total vs subtotal, D1/D2 lymphadenectomy, reconstruction methods)
4. Postoperative complications & management (dumping syndrome, nutritional deficiencies, anastomotic leak)
5. All of the above, covered one section at a time

Gastric Carcinoma: Pathology & Staging

1. Early vs. Advanced Gastric Cancer

• Early gastric cancer (EGC): tumor confined to the mucosa and submucosa, regardless of lymph node status (T1, any N). This is important because EGC is eminently curable, with 5-year survival rates around 90%. In Japan, where endoscopic screening is widespread, roughly one-third of diagnosed cancers are at this stage. In the UK/West, early diagnosis is far less common because dyspeptic patients are not always referred for prompt endoscopy - Bailey and Love's Short Practice of Surgery, p. 1192
• Advanced gastric cancer: invades into or beyond the muscularis propria. Prognosis drops sharply once this occurs.

• Type I - protruding
• Type II - superficial (IIa elevated, IIb flat, IIc depressed)
• Type III - ulcerated

2. Lauren Classification (histologic type)

3. Borrmann Classification (macroscopic type of advanced disease)

• Type I - Polypoid
• Type II - Fungating/ulcerating (localized, sharply demarcated ulcer)
• Type III - Infiltrating/ulcerating (ulcer with poorly defined, infiltrative margins)
• Type IV - Diffusely infiltrating (linitis plastica - "leather bottle stomach")

4. Molecular Subtypes (TCGA classification)

1. Epstein-Barr virus (EBV) positive
2. Microsatellite unstable (MSI)
3. Genomically stable
4. Chromosomal instability

5. TNM Staging (AJCC 8th edition)

• T stage: depth of tumor invasion (T1 = mucosa/submucosa; T2 = muscularis propria; T3 = subserosa; T4 = serosa/adjacent structures)
• N stage: number of regional lymph nodes involved (N0 through N3, based on node count rather than station in the 8th edition)
• M stage: presence (M1) or absence (M0) of distant metastasis, including peritoneal seeding

• Upper endoscopy with biopsy (histologic confirmation)
• CT chest/abdomen/pelvis for distant disease
• Endoscopic ultrasound (EUS) for T-stage depth and regional nodal assessment
• FDG-PET/CT in selected cases
• Staging laparoscopy with peritoneal lavage/cytology before major resection or neoadjuvant therapy, to detect occult peritoneal metastases not seen on CT - a step increasingly emphasized in recent literature (systematic review, PMID 37581636).

Gastric Cancer: Systemic Treatment Options

1. Chemotherapy

• MAGIC trial: 503 patients with gastric, GEJ, or distal esophageal cancer randomized to surgery alone vs. neoadjuvant/adjuvant ECF (epirubicin, cisplatin, 5-FU). The chemotherapy arm showed significantly improved 5-year survival (36% vs 23%) and better progression-free/overall survival - Sleisenger and Fordtran's Gastrointestinal and Liver Disease, p. 978. This established preoperative chemotherapy as standard prior to surgery.
• FLOT4 trial: perioperative FLOT (docetaxel, oxaliplatin, fluorouracil/leucovorin) significantly improved progression-free and overall survival compared to ECF/ECX, making FLOT the preferred regimen in fit patients undergoing perioperative treatment for gastric/GEJ adenocarcinoma - Sleisenger and Fordtran's, p. 978.
• Standard-of-care preoperative regimens generally combine a platinum compound (cisplatin or oxaliplatin) with a fluorinated pyrimidine (5-FU or capecitabine), given for 3-4 cycles before surgery. An alternative is FOLFOX (5-FU, leucovorin, oxaliplatin) - Harrison's Principles of Internal Medicine, 22e, p. 692.
• Patients who receive neoadjuvant chemotherapy as part of a perioperative protocol should complete the adjuvant cycles once recovered from surgery - Sabiston Textbook of Surgery.
• Because <50% of patients tolerate/complete postoperative chemotherapy, some centers favor "total neoadjuvant therapy" (giving all planned chemotherapy before surgery) - Harrison's, p. 692.

• Intergroup Trial 0116 (INT-0116/MacDonald regimen): 603 patients randomized to surgery alone vs. surgery + adjuvant 5-FU/leucovorin + radiotherapy. Surgery-alone arm had shorter median survival (27 vs 36 months) and worse relapse-free survival. This established adjuvant chemoradiation as U.S. standard of care, historically - Sleisenger and Fordtran's, p. 979.
• CLASSIC/S-1 trials (Asian populations): adjuvant chemotherapy (e.g., S-1, an oral fluoropyrimidine) after D2 gastrectomy improved 5-year outcomes in stage II/III disease compared to surgery alone - Schwartz's Principles of Surgery, 11e.
• For patients who did NOT receive preoperative chemotherapy, have stage II/III disease, or had a less-than-D2 resection (<15 nodes examined), postoperative chemotherapy or chemoradiation remains an option - Harrison's, p. 692.
• A 2010 JAMA meta-analysis confirmed a survival benefit of adjuvant chemotherapy for resectable gastric cancer.

• Because systemic chemotherapy poorly penetrates peritoneal metastases, hyperthermic intraperitoneal chemotherapy (HIPEC) has been studied for patients at high risk of microscopic peritoneal residual disease (serosal invasion, node-positive). A randomized trial of 248 patients showed improved overall survival with postoperative HIPEC, most pronounced in stage III/IV disease. A meta-analysis found a significantly reduced risk of death (OR 0.60), though results across trials are inconsistent and this remains an area of ongoing investigation rather than universal standard - Sleisenger and Fordtran's, p. 979.

• Cytotoxic backbone remains platinum + fluoropyrimidine (e.g., FOLFOX), shown superior to best supportive care in trials from the 1980s-90s - Harrison's, p. 692.

2. Targeted Therapy

• Approximately 13-30% of gastric cancers overexpress/amplify HER2 - all gastric cancer specimens should be tested for HER2 status as part of routine pathologic workup - Sabiston Textbook of Surgery, p. 1808.
• Trastuzumab (Herceptin), a monoclonal anti-HER2 antibody, combined with a fluoropyrimidine (5-FU or capecitabine) plus cisplatin, is standard first-line therapy for HER2-positive advanced gastric cancer. A phase III trial of 594 patients with HER2-overexpressing advanced gastric cancer showed improved median survival with chemo + trastuzumab vs. chemo alone - Current Surgical Therapy, 14e.
• Bailey and Love's notes the survival benefit is real but modest in absolute terms (~4 months), and treatment cost is high, affecting cost-effectiveness discussions in some health systems - Bailey and Love's Short Practice of Surgery, p. 1193.
• Notably, adding trastuzumab to preoperative (neoadjuvant) chemotherapy has not improved outcomes in HER2-positive resectable disease - the benefit is established mainly in the advanced/metastatic setting - Harrison's, p. 692.
• Fam-trastuzumab deruxtecan: a newer HER2-targeted antibody-drug conjugate (antibody linked to a topoisomerase-inhibiting payload), used as later-line therapy after progression on first-line HER2-targeted treatment - Harrison's, p. 692; Goodman & Gilman's Pharmacological Basis of Therapeutics.

3. Immunotherapy (Immune Checkpoint Inhibitors)

• CheckMate 649 trial: 1,581 patients with HER2-negative advanced gastric/GEJ cancer randomized to nivolumab (PD-1 inhibitor) + chemotherapy vs. chemotherapy alone. Significant improvements in overall survival, progression-free survival, and response rate, with the effect most pronounced in patients with PD-L1 combined positive score (CPS) > 5. This led to guideline recommendations for nivolumab + chemotherapy as first-line therapy in HER2-negative, PD-L1-expressing advanced disease - Harrison's, p. 693.
• Pembrolizumab (PD-1 inhibitor) is also approved and used, particularly in patients with MSI-high/dMMR tumors, where checkpoint inhibition can be highly effective, sometimes even replacing chemotherapy in that molecular subgroup. Combinations like nivolumab plus ipilimumab (PD-1 + CTLA-4) may be used as first-line therapy in MSI/dMMR metastatic disease - Harrison's, p. 693.
• Biomarker testing (PD-L1 CPS, MSI/MMR status, HER2, EBV status) is now integral to selecting systemic therapy - reflecting the TCGA molecular subtyping discussed in the pathology section.
• Checkpoint immunotherapy is also being explored in the neoadjuvant setting - the DANTE trial and others are studying immunotherapy combined with FLOT preoperatively, with encouraging early pathologic response data, though this remains investigational - Harrison's, p. 692; Yamada's Textbook of Gastroenterology.
• Sabiston notes that while checkpoint immunotherapy is an "exciting recent development," only a minority of patients (those with favorable biomarkers) currently benefit - it is not yet broadly applicable across all gastric cancer - Sabiston Textbook of Surgery, p. 1807.

Recent Evidence (2025 Systematic Reviews/Meta-Analyses) - Worth Noting

• A 2025 systematic review and meta-analysis of RCTs (PMID 40032744) compared immunotherapy or targeted therapy vs. best supportive care in advanced gastric cancer, reinforcing survival benefit but also highlighting quality-of-life tradeoffs.
• A 2025 network meta-analysis (PMID 39996912) specifically stratified immunotherapy + chemotherapy benefit by PD-L1 CPS cutoffs, suggesting the magnitude of benefit is highly threshold-dependent - relevant for patient selection.
• Two 2025 meta-analyses (PMID 40540446 and PMID 41184754) evaluated immunotherapy-based neoadjuvant regimens in locally advanced gastric cancer, suggesting improved pathologic response rates, though these are still moving from investigational to established standard-of-care status.

Gastrectomy: Surgical Technique

1. Total vs. Subtotal (Distal) Gastrectomy

• Performed through a long upper midline incision
• The stomach is removed en bloc with the entire greater and lesser omentum
• Sequence: the transverse colon is separated from the greater omentum, subpyloric nodes are dissected, the first part of the duodenum is divided (usually with a stapler), hepatic and suprapyloric nodes are cleared, the right gastric artery is divided at its origin, dissection continues to the origin of the left gastric artery (divided at origin), then along the splenic artery clearing nodes on the superior pancreas and splenic hilum
• The spleen can often be preserved if not directly involved, allowing access to nodal tissue around the upper stomach and gastro-esophageal junction (GOJ)
• The esophagus is divided with stay sutures and a soft non-crushing clamp; resection margins must be >5 cm clear of tumor, with frozen section performed if margin involvement is in doubt
• Continuity is restored with a Roux-en-Y loop
• Reference: Bailey and Love's Short Practice of Surgery, p. 1196

• Technique is similar to total gastrectomy, but the proximal stomach is preserved, with its blood supply maintained via the short gastric arteries
• Unnecessary to remove the entire stomach when the tumor is distal
• Reconstruction options include a Billroth II/Pólya-type gastrojejunostomy or, preferably, a Roux loop to reduce enterogastric bile reflux
• Reference: Bailey and Love's Short Practice of Surgery, p. 1196-1197

2. D1 vs. D2 (vs. D1+) Lymphadenectomy

• D1: removal of the perigastric lymph nodes only
• D2: additionally clears nodes around the major arterial trunks (left gastric, common hepatic, celiac axis, splenic artery/hilum)
• In practice, most specialist centers now perform a radical D2 lymphadenectomy while sparing the spleen and pancreas (avoiding routine splenectomy/distal pancreatectomy, which historically drove much of the morbidity/mortality attributed to D2 dissection) - Bailey and Love's, p. 1196; Sabiston, p. 1807.

• Early Western randomized trials (Cuschieri/UK MRC trial, Dutch trial) showed D2 associated with higher postoperative morbidity, mortality, and length of stay, with no early survival difference.
• However, long-term follow-up of the Dutch trial (15 years) showed D2 was associated with lower locoregional recurrence and gastric cancer-related death, and improved disease-specific/recurrence-free survival, despite no difference in overall survival - Sabiston, p. 1808; Yamada's Textbook of Gastroenterology.
• The Italian Gastric Cancer Study Group trial, using surgeons specifically trained in pancreas-preserving D2 technique at high-volume centers, showed better perioperative safety profiles than earlier trials - Fischer's Mastery of Surgery, 8e.
• D3 (super-extended) dissections have not shown additional survival benefit over D2 and are not standard - Current Surgical Therapy, 14e.
• Bottom line reflected across sources: D2 lymphadenectomy at experienced, high-volume centers with pancreas/spleen preservation is now the standard for curative-intent resection in most specialized practice (standard in Asia; increasingly adopted in the West) - Schwartz's Principles of Surgery, 11e.

3. Reconstruction Methods

• Billroth I: gastroduodenal anastomosis (remaining stomach directly anastomosed to duodenum) - simplest, preserves duodenal passage
• Billroth II (Pólya): gastrojejunal anastomosis with the duodenal stump closed off (loop reconstruction, bypassing duodenum) - historically common but associated with more enterogastric bile reflux
• Roux-en-Y gastrojejunostomy: increasingly preferred over Billroth II because it reduces bile reflux gastritis/esophagitis
• Reference: Bailey and Love's, p. 1191, "Gastrectomy-based procedures"

• Roux-en-Y esophagojejunostomy is the standard reconstruction
• The Roux (alimentary) limb should be at least 50 cm long to prevent bile reflux esophagitis
• Technique: a purse-string suture is placed in the cut end of the esophagus; a circular stapler introduced through the open end of the Roux loop staples the esophagus end onto the side of the jejunal loop; the blind end of the loop is then closed with sutures or a linear stapler (alternatively, an end-to-end anastomosis can be fashioned)
• The Roux loop can be positioned antecolic or retrocolic
• An end-to-side jejunojejunostomy completes the reconstruction at a convenient distal point
• Some evidence supports constructing a jejunal pouch for long-term nutritional/intestinal benefit, though this adds complexity
• Reference: Bailey and Love's, p. 1196

Key Complications Related to Reconstruction Choice (brief)

• Esophagojejunostomy leak: often manageable conservatively since only saliva/food leaks (not bile) due to the Roux configuration
• Duodenal stump leak: usually reflects distal obstruction/kinking at the Roux-en-Y anastomosis; managed with drainage and a controlled fistula (Foley catheter) if biliary peritonitis develops
• Secondary hemorrhage: from exposed vessels after radical dissection in the setting of septic collections - a serious, sometimes catastrophic complication
• Reference: Bailey and Love's, p. 1197