Treatment Approach for Gastric Invasive Adenocarcinoma

Initial Staging and Assessment

The European Society for Medical Oncology recommends a complete staging workup, including physical examination, blood count, liver and renal function tests, endoscopy with biopsy, CT scan of abdomen and pelvis, and chest X-ray or CT of thorax, for patients with gastric invasive adenocarcinoma 3
Endoscopic ultrasound (EUS) helps determine proximal and distal tumor extent, though less useful for antral tumors, according to the European Society for Medical Oncology 3
The National Comprehensive Cancer Network recommends laparoscopy with or without peritoneal washings for potentially resectable cases to exclude metastatic disease, with a strength of evidence of category 2A 3, 4
PET/CT may be useful for detecting occult metastatic disease, though histologic confirmation of PET-avid lesions is recommended, with a level of evidence of IIIB 4
HER2 testing should be performed if metastatic disease is documented or suspected, according to the National Comprehensive Cancer Network, with a category 1 recommendation 4

Treatment planning must involve surgeons, medical and radiation oncologists, gastroenterologists, radiologists, and pathologists, as recommended by the European Society for Medical Oncology and the National Comprehensive Cancer Network 3, 4
Stage should be determined according to the TNM system and AJCC stage grouping, with a level of evidence of III 3

Surgical resection is the only potentially curative modality for stages I-IV M0, according to the European Society for Medical Oncology, with a category 1 recommendation 3
The extent of gastric resection depends on tumor location, with distal gastrectomy for distal tumors and total gastrectomy for proximal tumors, as recommended by the Japanese Gastric Cancer Association 2
Adequate resection margins are ≥3 cm for Borrmann I-II tumors and ≥5 cm for Borrmann III-IV, with a level of evidence of IIIB 5
D2 lymphadenectomy is standard for resectable gastric cancer classified as cT1N+ and cT2-4N-/+ , with a category 1 recommendation 5
At least 14, optimally 25 lymph nodes should be examined pathologically, according to the European Society for Medical Oncology and the Japanese Gastric Cancer Association, with a level of evidence of III 3, 5
Splenectomy is not routinely recommended unless directly involved by tumor, as stated by the Japanese Gastric Cancer Association, with a category 2B recommendation 2

For very early gastric cancers (T1a), endoscopic resection may be appropriate if they are well-differentiated, ≤2 cm, confined to mucosa, and non-ulcerated, according to the European Society for Medical Oncology, with a category 2A recommendation 1
No additional treatment is necessary for Tis and T1N0 tumors with R0 resection, as stated by the National Comprehensive Cancer Network, with a category 1 recommendation 6

Perioperative chemotherapy is the standard of care in most of Europe for stage Ib or higher, according to the European Society for Medical Oncology, with a category 1 recommendation 1, 2
The ECF regimen (epirubicin 50 mg/m², cisplatin 60 mg/m², and continuous 5-FU 200 mg/m²/day) given as three cycles pre- and post-operatively significantly improves 5-year survival from 23% to 36.3%, with a level of evidence of IB 3
ECX (epirubicin, cisplatin, capecitabine) is commonly used as an alternative to ECF, according to the European Society for Medical Oncology, with a category 2A recommendation 1

Concurrent chemoradiotherapy is recommended for patients with unresectable locally advanced gastric cancer with good performance status, according to the National Comprehensive Cancer Network, with a category 1 recommendation 7
Chemotherapy regimens used with radiation include capecitabine + paclitaxel, cisplatin + 5-FU/capecitabine/S-1, and oxaliplatin + 5-FU/capecitabine/S-1, with a level of evidence of IIIB 7
Re-evaluation for potential surgical resectability should be performed after treatment response, as recommended by the National Comprehensive Cancer Network, with a category 2A recommendation 7

Palliative chemotherapy is recommended for patients with stage IV disease and good performance status, according to the European Society for Medical Oncology and the National Comprehensive Cancer Network, with a category 1 recommendation 4, 8
Common regimens include combinations incorporating platinum agents, fluoropyrimidines, anthracyclines, and taxanes, with a level of evidence of IIIB 7, 8, 9

Inadequate lymph node evaluation (fewer than 14 nodes) may lead to understaging and suboptimal treatment, according to the European Society for Medical Oncology and the Japanese Gastric Cancer Association, with a level of evidence of III 3, 5
Omitting laparoscopy in potentially resectable cases may miss peritoneal metastases not detected on imaging, as stated by the European Society for Medical Oncology, with a category 2B recommendation 3
Routine splenectomy increases postoperative complications without survival benefit, according to the Japanese Gastric Cancer Association, with a category 2B recommendation 2