What is the primary treatment approach for a gastric neoplasm?

Primary Treatment Approach for Gastric Neoplasm

For localized resectable gastric cancer (stage IB or higher), the primary treatment is perioperative chemotherapy with a triplet regimen (fluoropyrimidine, platinum compound, and docetaxel) for 2-3 months pre- and post-operatively, combined with radical gastrectomy with D2 lymphadenectomy. 1, 2

Treatment Algorithm by Stage

Very Early Disease (T1a)

• Endoscopic resection (ESD preferred over EMR) is the primary treatment when ALL criteria are met: confined to mucosa, well-differentiated (G1-2), non-ulcerated, and ≤2 cm diameter 1, 2, 3
• For lesions 10-15 mm with very low probability of advanced histology (Paris 0-IIa), EMR is acceptable 1
• En bloc resection with R0 margins (no tumor at margins) is mandatory 1
• If expanded criteria are met (up to 2 criteria: G1/G2 with ulceration up to 30mm diameter, or G3 without ulceration up to 20mm diameter), endoscopic resection may still be considered 1

Early Disease Not Meeting Endoscopic Criteria (T1b and beyond)

• Surgery alone with D1+ lymphadenectomy (perigastric plus local N2 nodes) for T1 tumors not suitable for endoscopic resection 1
• No additional treatment needed for Tis and T1N0 with R0 resection 4

Localized Resectable Disease (Stage IB-III)

This is the most critical decision point where treatment paradigm significantly impacts survival.

Perioperative Chemotherapy (Preferred Approach)

• Triplet regimen with fluoropyrimidine + platinum compound + docetaxel for 2-3 months preoperatively, then surgery, then 2-3 months postoperatively 1, 2
• This approach is superior to adjuvant-only therapy because neoadjuvant chemotherapy is better tolerated, causes tumor downsizing, and allows more curative resections 1
• Alternative regimens include ECF (epirubicin 50 mg/m², cisplatin 60 mg/m², continuous 5-FU 200 mg/m²/day) or ECX (epirubicin, cisplatin, capecitabine) 4

Surgical Resection Specifications

• D2 lymphadenectomy is standard (perigastric lymph nodes plus those along proper/common hepatic artery, splenic artery, and celiac axis) 1, 2
• Minimum 15-16 lymph nodes must be examined for adequate staging; optimal number is >30 1, 2
• Proximal margin requirements: 3 cm for expansive/intestinal histotypes; 5 cm for infiltrative/poorly cohesive/diffuse histotypes 1, 2
• Subtotal gastrectomy acceptable if adequate proximal margin achieved; otherwise total gastrectomy required 1
• Surgery must be performed in high-volume specialized centers (minimum 15-20 resections per surgeon annually) 1

Adjuvant-Only Approach (Second-Line Option)

• For patients with stage IB who underwent surgery without preoperative chemotherapy 1
• Doublet chemotherapy for 6 months total duration: fluoropyrimidine plus oxaliplatin or docetaxel 1, 3
• This approach is less preferred because adjuvant chemotherapy is less well tolerated than neoadjuvant 1

Locally Advanced Unresectable Disease

• Concurrent chemoradiotherapy is recommended for patients with good performance status 1, 4
• Chemotherapy regimens with radiation: capecitabine + paclitaxel, cisplatin + 5-FU/capecitabine, or oxaliplatin + 5-FU/capecitabine 4
• Re-evaluate for surgical resectability after treatment response via multidisciplinary team discussion 1, 4
• If tumor becomes resectable after downstaging, proceed with radical resection 1

Metastatic Disease (Stage IV)

• Palliative chemotherapy with combination regimens for patients with good performance status 1, 2, 3, 5
• First-line: platinum + fluoropyrimidine doublet 5
• For HER2-positive tumors: add trastuzumab to first-line chemotherapy 2, 3, 5
• Second-line: ramucirumab (anti-angiogenic) alone or with paclitaxel 6, 5
• Third-line: nivolumab or pembrolizumab (anti-PD-1) 5
• Median survival with sequential chemotherapy lines is less than 1 year 5

Critical Staging Requirements Before Treatment

Accurate staging is essential to avoid treatment errors:

• Contrast-enhanced CT of thorax, abdomen, and pelvis 2, 3
• Endoscopic ultrasound (EUS) for determining T and N stages, especially in early disease 2, 4
• Laparoscopy with peritoneal washings is mandatory for all stage IB-III cancers to detect occult peritoneal metastases not visible on CT 2, 4, 3
• HER2 testing required if metastatic disease documented or suspected 4, 3
• PET imaging may improve detection of involved lymph nodes/metastatic disease 2

Common Pitfalls to Avoid

• Omitting diagnostic laparoscopy in potentially resectable cases: This misses peritoneal metastases in up to 30% of patients, leading to inappropriate treatment selection 2, 4
• Inadequate lymph node harvest (<15 nodes): Results in understaging and suboptimal treatment planning 1, 2, 4
• Proceeding directly to surgery without perioperative chemotherapy for stage IB or higher: Misses opportunity for tumor downstaging and improved survival 1, 2
• Routine splenectomy: Increases complications without survival benefit; only perform if tumor directly invades spleen 4
• Inadequate resection margins: Particularly dangerous in poorly cohesive/diffuse histotypes where 5 cm margin is required 1
• Clinical understaging of T1N0 disease: 27% of clinical T1N0 tumors are upstaged at surgery, particularly poorly differentiated tumors (42% upstaging rate) and fundus/body locations 7

Multidisciplinary Team Requirement

All treatment decisions must involve: surgeons, medical oncologists, radiation oncologists, gastroenterologists, radiologists, pathologists, dieticians, and nurse specialists 4, 3