A 62-year-old woman from Delhi undergoes subtotal gastrectomy with D2 lymphadenectomy for a T2N1M0 gastric adenocarcinoma of the antrum. Intraoperative findings include a 3.5 cm tumour with 4 positive perigastric lymph nodes and 8 negative distant lymph nodes (total 18 nodes examined). Final histopathology confirms adequate margins (R0 resection) and no involvement of the proximal stomach. The patient recovers well from surgery. What is the most appropriate next step in management?

Explanation

## Pathological Staging This patient has: - **T2N1M0** (Stage IIA) gastric cancer - **R0 resection** (adequate margins) - **18 lymph nodes examined** (adequate D2 dissection, ≥15 nodes recommended) - **4 positive perigastric lymph nodes** (N1 = 1–2 regional nodes; N2 = 3–6 regional nodes) **Key Point:** The presence of 4 positive nodes actually upgrades this to **N2 disease**, making it **Stage IIIA** (T2N2M0), not Stage IIA. ## Adjuvant Therapy Indications **High-Yield:** Adjuvant chemotherapy is indicated for Stage IB and above in gastric cancer. The evidence base: | Trial / Guideline | Indication | Regimen | Benefit | |-------------------|-----------|---------|--------| | ACTS-GC (Japan) | Stage II–III | S-1 monotherapy | 3-year DFS: 72.3% vs 60.3% (p=0.002) | | CLASSIC (Korea) | Stage II–IIIB | Capecitabine + Cisplatin | 3-year DFS: 74% vs 59% (p<0.001) | | MAGIC (UK) | Resectable, Stage IB–III | ECF perioperative | 5-year OS: 36% vs 23% | | NCCN / ESMO | Stage IB–III (R0) | ECF, ECX, or DCF | Standard of care | **Clinical Pearl:** This patient has Stage IIIA disease (T2N2M0) and is an ideal candidate for adjuvant chemotherapy. S-1 monotherapy is common in Asia; ECF/ECX are standard in Western practice. ## Adjuvant Chemotherapy Regimens ```mermaid flowchart TD A[Resected gastric cancer, Stage IB-III]:::outcome --> B{Fit for chemotherapy?}:::decision B -->|Yes| C{Preferred regimen?}:::decision B -->|No| D[Best supportive care]:::action C -->|ECF/ECX| E[Epirubicin + Cisplatin + 5-FU/Capecitabine]:::action C -->|S-1| F[Oral S-1 monotherapy]:::action C -->|Capecitabine-Cisplatin| G[Capecitabine + Cisplatin]:::action E --> H[6 cycles over 18-24 weeks]:::action F --> I[1 year of S-1]:::action G --> H H --> J[Follow-up surveillance]:::action I --> J ``` **Key Point:** Adjuvant chemotherapy should begin within 6–8 weeks of surgery in fit patients. The ACTS-GC trial showed that S-1 monotherapy for 1 year improved disease-free survival. ECF/ECX (3 cycles) is also acceptable. ## Why NOT Radiotherapy Alone or Chemoradiotherapy? **Warning:** In resected gastric cancer with adequate D2 dissection and R0 margins: - **Radiotherapy alone** is inferior to chemotherapy and is not standard - **Chemoradiotherapy** (INT-0116 trial) is reserved for **inadequate nodal dissection** (D0/D1) or **R1/R2 margins** This patient had adequate D2 dissection (18 nodes) and R0 margins, so chemotherapy alone is preferred. ## Follow-up After Adjuvant Therapy - **Surveillance endoscopy:** Not routine; only if symptoms - **CT imaging:** Baseline post-op, then 6-monthly for 2 years, then annually - **Tumour markers:** CEA and CA 19-9 at baseline; not recommended for routine follow-up - **Nutritional support:** Iron, B12, calcium supplementation if subtotal gastrectomy