Definition

What Is Stomach Cancer?

Gastric (stomach) cancer most often arises as adenocarcinoma from the cells lining the stomach. Globally, it is the 5th most common cancer and a leading cause of cancer death, particularly in East Asia, Eastern Europe, and South America. Incidence has declined dramatically in Western countries due to refrigeration and reduced H. pylori prevalence.

Two distinct subtypes: Intestinal-type, older patients, distal stomach, strongly linked to H. pylori infection and dietary factors (salt, smoked foods). Diffuse-type, younger patients, often hereditary (CDH1 mutations⁸), poorly differentiated, worse prognosis. Cardia adenocarcinomas (upper stomach near esophagus) are increasingly common in Western populations and linked to GERD/Barrett's.

H. pylori infection is responsible for ~60-90% of non-cardia gastric cancers.² Chronic infection causes gastritis → atrophic gastritis → intestinal metaplasia → dysplasia → cancer. The good news: eradicating H. pylori reduces cancer risk significantly, especially when done early.

💡 Key Insight: H. pylori is a Group 1 carcinogen. If you have a family history of stomach cancer, or symptoms of chronic gastritis (recurrent dyspepsia, ulcers), get tested for H. pylori. Eradication reduces gastric cancer risk significantly. Endoscopic surveillance is recommended for patients with atrophic gastritis or intestinal metaplasia.

Types of Gastric Cancer

🌱 Intestinal-Type Adenocarcinoma

Most common in older patients. Distal stomach. Linked to H. pylori, salt, smoked foods, low vegetables. Develops over years through gastritis → metaplasia → dysplasia → cancer.

🌗 Diffuse-Type / Signet Ring

Younger patients, women more commonly. Linitis plastica ("leather bottle stomach"). CDH1 hereditary mutation common. Worse prognosis. Hereditary diffuse gastric cancer syndrome warrants prophylactic gastrectomy.

🌑 Cardia / GE Junction

Upper stomach near esophagus. Increasingly common in Western countries. Linked to GERD, Barrett's esophagus, obesity. Often grouped with esophageal cancer for treatment.

Signs & Symptoms

Symptoms of Stomach Cancer

Early-stage cancer often asymptomatic or mimics common dyspepsia. Persistent symptoms in patients >55 or with alarm features warrant endoscopy.

🔍 Early / Common Symptoms

😖

Persistent Indigestion / Dyspepsia

Upper abdominal discomfort, burning, fullness, bloating. Often dismissed as GERD or "stress." Persistent or worsening symptoms in older adults warrant endoscopy.

🍽️

Early Satiety

Feeling full quickly with small meals. Reduced eating capacity. May indicate tumor narrowing or rigid stomach (linitis plastica). Often combined with weight loss.

🤢

Nausea, Loss of Appetite

Persistent reduced appetite, food aversion. May develop aversion to specific foods (especially meat). Vague but persistent nausea.

⚖️

Unexplained Weight Loss

10+ pounds without trying. Combined with dyspepsia or early satiety, raises concern significantly. Always investigate in adults >55.

⚠️ Alarm Features (Urgent Endoscopy)

🩸

GI Bleeding / Anemia

Hematemesis (vomiting blood), melena (black tarry stools), or unexplained iron-deficiency anemia in older men or postmenopausal women. URGENT endoscopy required.

🦴

Vomiting (Especially of Undigested Food)

May indicate gastric outlet obstruction by tumor. Eating food and vomiting hours later. Severe weight loss often accompanies.

😖

Dysphagia (Difficulty Swallowing)

Solids stick or feel like they "get stuck." May indicate tumor at gastroesophageal junction or cardia. URGENT evaluation.

💪

Palpable Mass / Lymph Nodes

Epigastric mass. Left supraclavicular lymph node (Virchow's node), classic sign of metastatic gastric cancer. Umbilical nodule (Sister Mary Joseph). Late findings.

Diagnosis

How Stomach Cancer Is Diagnosed

🔬 Diagnosis & Staging

🔬 Upper Endoscopy + Biopsy

PRIMARY diagnostic test. Direct visualization + multiple biopsies of suspicious lesions, ulcers, mass. Should sample edges and base of ulcers.

📡 Endoscopic Ultrasound (EUS)

Determines T-stage (depth of invasion) and N-stage (regional nodes). Critical for staging and treatment planning. Can biopsy enlarged lymph nodes.

📡 CT Chest/Abdomen/Pelvis

Standard staging, evaluates for liver, lung, peritoneal metastases. Sometimes PET-CT for further evaluation.

🔬 Diagnostic Laparoscopy

For locally advanced disease before surgery, detects small peritoneal metastases not visible on imaging. Peritoneal washings.

🧬 H. pylori & Molecular Testing

🦠 H. pylori Testing

Urea breath test, stool antigen, biopsy testing. EVERY gastric cancer patient should be tested. Eradication for those positive (treat family members too).

🧬 HER2 Testing

~15-20% of gastric cancers are HER2-positive. Determines eligibility for trastuzumab (Herceptin), significant survival benefit when added to chemo.⁶

🧬 PD-L1 (CPS)

Combined positive score. CPS ≥5 (some indications ≥1) makes patients eligible for immunotherapy (pembrolizumab, nivolumab) addition to chemo.

🧬 MSI, EBV, Claudin 18.2

Microsatellite instability (immunotherapy responders), EBV-positive (better prognosis), Claudin 18.2 (new target, zolbetuximab).

Treatment Comparison

Holistic vs. Conventional Treatment

🌿 HOLISTIC

💊 CONVENTIONAL

🌿

Holistic / Integrative Approach

PRIMARY PREVENTION is extremely effective, H. pylori eradication, Mediterranean diet, lifestyle factors

Primary Prevention

H. pylori eradication can reduce gastric cancer risk significantly, especially when done early

Dietary Prevention

Mediterranean diet, high vegetable/fruit, low salt/smoked foods cuts risk dramatically

Surveillance

Atrophic gastritis, intestinal metaplasia, family history → endoscopic surveillance

Post-Gastrectomy

B12, iron, calcium, fat-soluble vitamin replacement; small frequent meals essential

Comprehensive Prevention & Support

H. pylori test and treat, single most important primary prevention. Test family members.
Mediterranean / plant-rich diet, 5-7+ servings vegetables and fruits daily. Inverse association with gastric cancer.
Fresh vs preserved foods, refrigeration (a major reason gastric cancer rates fell in West). Choose fresh foods over preserved.
Allium vegetables daily, garlic, onions, leeks, shallots. Strong inverse association with gastric cancer.
Limit salt, <5g/day. High salt damages stomach lining, promotes H. pylori, increases cancer risk.⁴
Limit preserved, smoked, salted foods, bacon, sausage, pickled vegetables, salted fish. Major risk factor in Asian populations.
Quit smoking, doubles gastric cancer risk; quit at any age helps
Vitamin C from food, citrus, peppers, berries. Inverse association with gastric cancer.
Green tea (regular consumption), EGCG and other polyphenols. Modest protective association.
Limit alcohol, heavy alcohol increases risk, especially with smoking
Maintain healthy weight, obesity increases cardia adenocarcinoma risk
Treat GERD, chronic reflux + Barrett's increases cardia/GEJ cancer risk
Endoscopic surveillance for atrophic gastritis, intestinal metaplasia, pernicious anemia, family history (CDH1 carriers)
Post-gastrectomy nutrition: B12 lifelong (injections), iron, calcium, vitamin D, small frequent meals to prevent dumping syndrome

✅ Stomach Cancer Is Largely Preventable: Gastric cancer rates dropped dramatically in Western countries due to refrigeration, reduced H. pylori, and increased vegetable intake. The same prevention works individually, test/treat H. pylori, eat Mediterranean, avoid smoked/salted foods, don't smoke.

💊

Conventional / Oncologic Approach

Surgery + perioperative chemo + targeted/immunotherapy for advanced disease

Early-Stage (T1a)

Endoscopic submucosal dissection (ESD), organ-preserving cure

Locally Advanced

Perioperative FLOT chemotherapy (3 cycles pre-op + 3 post-op) + gastrectomy

Metastatic HER2+

Trastuzumab + chemo; trastuzumab deruxtecan (Enhertu) for refractory disease

Metastatic Other

Chemo (FOLFOX, capecitabine + oxaliplatin) + pembrolizumab/nivolumab if PD-L1 high

Modern Treatment Algorithms

Very early-stage (T1a): endoscopic submucosal dissection (ESD), minimally invasive cure with organ preservation. Common in Asia, increasingly available in West.
Locally advanced resectable: perioperative FLOT (docetaxel + oxaliplatin + leucovorin + 5-FU), superior to ECF/ECX based on FLOT4 trial⁵. 3 cycles before + 3 cycles after gastrectomy.
Gastrectomy (total or subtotal) + D2 lymphadenectomy, extent depends on tumor location. High-volume centers significantly better outcomes.
Adjuvant therapy: continued chemo or chemoradiation (CROSS-style for GEJ) if perioperative not feasible
HER2-positive metastatic: trastuzumab + chemotherapy first-line; trastuzumab deruxtecan (Enhertu) for HER2+ refractory
PD-L1 CPS ≥5 metastatic: pembrolizumab + chemo (KEYNOTE-859); nivolumab + chemo for first-line
Claudin 18.2-positive: zolbetuximab + chemo, new targeted therapy (SPOTLIGHT trial)
MSI-high or dMMR: immunotherapy first-line (pembrolizumab + chemo or dual immunotherapy)
Second-line metastatic: ramucirumab + paclitaxel; trifluridine/tipiracil; pembrolizumab for selected
HIPEC (Hyperthermic Intraperitoneal Chemotherapy): for selected peritoneal-only disease at specialized centers
Palliative interventions: stenting for obstruction; gastrostomy/jejunostomy for nutrition; radiation for bleeding
CDH1 hereditary gastric cancer: consider prophylactic total gastrectomy

⚠️ Post-Gastrectomy Care Critical: Lifelong B12 supplementation (injections often needed). Iron supplementation. Calcium and vitamin D. Small frequent meals (5-6/day) to prevent dumping syndrome. Manage diarrhea and dumping symptoms. Work with experienced nutritionist.

Nutritional Strategy

Diet for Stomach Cancer

Mediterranean, fresh foods, low salt, no smoked/preserved meats. Post-gastrectomy: small frequent meals + lifelong nutrient replacement.

✅ Prioritize (Prevention):

🥬 Fresh Vegetables & Fruits

5-7+ servings daily. Strong inverse association with gastric cancer. Citrus, leafy greens, cruciferous especially protective.

🧄 Allium Vegetables Daily

Garlic, onions, leeks, shallots, scallions. Organosulfur compounds may reduce gastric cancer risk significantly.

🍵 Green Tea

2-3 cups/day. Long-term consumption associated with reduced gastric cancer in Asian populations.

🍅 Vitamin C-Rich Foods

Citrus, bell peppers, berries, kiwi. Inhibits formation of carcinogenic N-nitroso compounds in stomach.

🍽️ Post-Gastrectomy: Small Frequent Meals

5-6 small meals/day. Chew thoroughly. Liquids between (not with) meals. Lie down briefly after eating. Prevents dumping syndrome.

❌ Strictly Limit:

🥓 Smoked, Cured, Salted Foods

Bacon, sausage, ham, salted fish, pickled vegetables. Nitrates/nitrites and salt damage stomach lining. WHO classifies processed meats as Group 1 carcinogens.

🧂 Excessive Salt

<5g/day. Asian high-salt populations have highest gastric cancer rates. Damages mucosa, promotes H. pylori colonization.

🚭 Tobacco

Doubles gastric cancer risk. Synergistic with H. pylori and alcohol. Continuing to smoke after diagnosis worsens treatment response.

🍷 Heavy Alcohol

Especially when combined with smoking. Damages stomach lining. Limit to <1 drink/day.

🍔 Ultra-Processed Foods

Strong association with multiple cancers. Replace with whole foods. Especially limit instant noodles, processed meats, packaged snacks.

Supplement Protocol

Evidence-Based Supplements

Post-gastrectomy: lifelong B12, iron, calcium, vitamin D. For prevention: focus on food-based nutrients first.

Supplement	Mechanism & Evidence	Suggested Dose	Timing	Notes
Vitamin B12 (Post-Gastrectomy)	Required after gastrectomy (loss of intrinsic factor). Without replacement, severe deficiency develops.	1,000mcg IM monthly OR 1,000-2,000mcg sublingual daily	IM monthly or daily sublingual	LIFELONG after total gastrectomy. Check B12 levels regularly.
Iron (Post-Gastrectomy)	Reduced absorption after gastrectomy. Often need supplementation; sometimes IV iron.	Per blood tests	With vitamin C, away from calcium	Test ferritin regularly. Anemia common.
Calcium + Vitamin D3	Reduced absorption after gastrectomy. Bone loss common. Test and replace.	Calcium 1,000-1,200mg + Vitamin D test 25-OH-D first and set the dose with your clinician	With meals (calcium); with fat (D)	DEXA scan to monitor bone density. Pair D with K2 200mcg. If you take warfarin, agree any vitamin K supplement with the clinician managing your anticoagulation before starting or stopping it: vitamin K antagonises warfarin, and changing your intake destabilises the INR. Consistency matters more than avoidance. This does not apply in the same way to direct oral anticoagulants such as apixaban or rivaroxaban.
Multivitamin (Post-Gastrectomy)	Multiple micronutrient deficiencies common. Address fat-soluble vitamins (A, D, E, K).	1 quality multivitamin daily	With food	Choose one with adequate B-complex.
Pancreatic Enzymes (If Indicated)	After gastrectomy, exocrine pancreatic insufficiency is common⁷, because food and pancreatic enzymes no longer arrive together. Discuss enzyme replacement with your team if you have fatty stools or weight loss.	Per oncology team	With meals	Discuss with surgical team and oncology nutritionist.
Omega-3 (EPA/DHA)	Anti-inflammatory; supports muscle preservation during chemo/recovery.	2,000-3,000mg EPA+DHA/day	With fat meal	Discuss with oncologist.
Probiotics	Modulate gut microbiome; may improve chemo tolerance, reduce H. pylori colonization (multi-strain).	10-30 billion CFU/day, multi-strain	With or without food	Especially after antibiotics for H. pylori eradication.
Vitamin C (Food-Based)	Inhibits N-nitroso compound formation in stomach. Prefer food sources.	500-1,000mg/day OR via diet	With meals	Citrus, peppers, berries, preferred over supplements.

References & Evidence Notes

Each numbered entry below is either a source you can follow or a note setting out what the evidence does and does not support. Both are numbered together so the markers in the text line up.

Last reviewed 25 August 2026. Supplement entries are cross-checked against the NIH National Center for Complementary and Integrative Health and the Linus Pauling Institute Micronutrient Information Center.⁹ Nothing on this page treats stomach cancer. The most effective preventive step here is not nutritional: if you have H. pylori, get tested and treated, because eradication is the one intervention with randomized trial evidence for reducing gastric cancer risk. Diet matters at the population level, mainly through less salt and preserved food and more vegetables, but those associations are observational and are not treatment. After gastrectomy the nutrition on this page becomes genuinely important, because the surgery permanently changes what you can absorb: vitamin B12 requires lifelong replacement, iron and calcium absorption fall, and dumping syndrome is common. That belongs with a specialist dietitian, not a supplement aisle. Tell your oncology team about every supplement you take.

SEER (National Cancer Institute) stomach cancer statistics, and GLOBOCAN/IARC for global figures. seer.cancer.gov. Source for annual US incidence of roughly 27,000, overall 5-year relative survival of about 36%, and the global ranking. Incidence has fallen substantially in Western countries, attributed largely to refrigeration replacing salt preservation and to declining H. pylori prevalence. ↩
IARC Monographs classify Helicobacter pylori as a Group 1 carcinogen. Roughly 60 to 90% of non-cardia gastric cancers are attributable to chronic infection, a range reflecting the detection method used: the worldwide attributable fraction is 74.7% on ELISA-based data and 89.0% on immunoblot (Plummer M, et al. Int J Cancer. 2015;136(2):487–490. PubMed 24889903), which drives the progression from gastritis to atrophic gastritis to intestinal metaplasia to dysplasia. Cardia and gastro-oesophageal junction cancers behave differently and are linked to reflux, Barrett's oesophagus and obesity rather than to H. pylori. ↩
On H. pylori eradication, which is why this page separates it from dietary advice. Randomized trials and their meta-analyses, including Cochrane reviews of eradication for gastric cancer prevention, show that treating H. pylori reduces subsequent gastric cancer incidence in infected people. That is a different grade of evidence from the dietary associations on this page, which come from observational cohorts, and antioxidant supplementation trials for gastric cancer prevention have generally been null. Eradication is a prescription antibiotic course, not a supplement. ↩
On salt and preserved foods: World Cancer Research Fund / AICR Continuous Update Project. wcrf.org. Salt-preserved foods are judged a probable cause of stomach cancer, and the highest-incidence regions historically had the highest intakes. The under-5 g/day salt figure on this page is the general population target, not a cancer-specific dose. ↩
FLOT4: Al-Batran SE, et al. Perioperative chemotherapy with fluorouracil plus leucovorin, oxaliplatin, and docetaxel versus fluorouracil or capecitabine plus cisplatin and epirubicin. Lancet. 2019;393:1948–1957. Basis for perioperative FLOT over ECF/ECX in locally advanced resectable disease. That is a comparison between two chemotherapy regimens. ↩
ToGA trial: Bang YJ, et al. Trastuzumab in combination with chemotherapy for HER2-positive advanced gastric cancer. Lancet. 2010;376:687–697. PubMed 20728210. Roughly 15 to 20% of gastric cancers are HER2-positive, and adding trastuzumab improved survival in that group. HER2 testing is therefore standard in advanced disease. ↩
On post-gastrectomy nutrition: total or partial gastrectomy causes loss of intrinsic factor and reduced gastric acid, so vitamin B12 requires lifelong replacement (often by injection) and iron and calcium absorption fall. Exocrine pancreatic insufficiency is also common after gastrectomy because food and pancreatic enzymes no longer arrive in the duodenum together. Dumping syndrome affects a substantial minority. This is specialist dietetic territory. ↩
On hereditary diffuse gastric cancer: CDH1 germline mutations underlie a distinct, often younger-onset, diffuse-type disease, and carriers are managed differently, including consideration of prophylactic gastrectomy. Family history of gastric cancer at a young age warrants genetic referral. ↩
National Center for Complementary and Integrative Health (NIH), nccih.nih.gov, and the Linus Pauling Institute Micronutrient Information Center, lpi.oregonstate.edu/mic.