Stomach Cancer (Gastric Cancer)

Overview

Gastric cancer develops in the stomach and is the fifth most commonly diagnosed cancer and a leading cause of cancer death worldwide, with more than one million new cases each year (Smyth et al., Lancet, 2020; Li et al., Gastroenterology, 2023). In the United States, roughly 30,000 people are diagnosed annually, and the median age at diagnosis is about 68 years, though the diagnosis is rising among people younger than 50 (Walter, JAMA, 2026; Patel et al., JAMA, 2026). It is more common in men than in women, and incidence is substantially higher in East Asia, Eastern Europe, and South America than in North America (Smyth et al., Lancet, 2020).

More than 90% of stomach cancers are adenocarcinomas, which are broadly divided into intestinal-type (associated with the stepwise "Correa cascade" of chronic inflammation) and diffuse-type (including signet-ring cell carcinoma and linitis plastica, which can spread through the stomach wall and the peritoneum) (Tey et al., Cochrane Database of Systematic Reviews, 2019; Sundar et al., Lancet, 2025). Worldwide, about 85% of cancers arise in the body or antrum (lower stomach) and 15% in the cardia (upper stomach); the location matters because cardia/GEJ cancers share risk factors with reflux and obesity, while non-cardia cancers are overwhelmingly driven by H. pylori (Patel et al., JAMA, 2026; Li et al., Gastroenterology, 2023). The central challenge of this disease is late diagnosis — because early tumors cause few symptoms, most U.S. patients present with weight loss or pain once disease is advanced, which is why recognizing risk factors and alarm symptoms is so important (Smyth et al., Lancet, 2020; Patel et al., JAMA, 2026).

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The dominant cause of non-cardia gastric cancer is chronic infection with Helicobacter pylori, a bacterium classified by the WHO/IARC as a class 1 (definite) carcinogen since 1994 and associated with nearly 90% of body-and-antrum cancers globally (Thrift et al., Nature Reviews Clinical Oncology, 2023; Müller & He, New England Journal of Medicine, 2023). H. pylori drives cancer through the Correa cascade — chronic gastritis progresses to gastric atrophy, intestinal metaplasia, dysplasia, and finally invasive adenocarcinoma — accumulating genetic and epigenetic damage along the way, amplified by bacterial virulence factors such as CagA and VacA (Sundar et al., Lancet, 2025; Malfertheiner et al., Nature Reviews Disease Primers, 2023). Importantly, although about half the world's population carries H. pylori, only roughly 1–3% of infected people develop gastric cancer, reflecting the combined influence of bacterial strain, host genetics, and environment (Sundar et al., Lancet, 2025).

Other contributing causes include Epstein-Barr virus infection (5–10% of cases), chronic atrophic gastritis and pernicious anemia, and — in a minority — inherited genetic mutations, most notably CDH1 in hereditary diffuse gastric cancer. Familial aggregation occurs in about 10% of cases, but known heritable mutations account for only about 1–3% of the global burden (Sundar et al., Lancet, 2025; Müller & He, New England Journal of Medicine, 2023).

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Risk Factors

Established risk factors include (Sundar et al., Lancet, 2025; Thrift et al., Nature Reviews Clinical Oncology, 2023; Walter, JAMA, 2026):

• H. pylori infection — the single most important and the most modifiable risk factor; eradication therapy reduces gastric cancer incidence by roughly 46% (Li et al., Gastroenterology, 2023).

• Tobacco smoking.

• Heavy alcohol use (≈4 or more drinks daily).

• Diet — high intake of salt, salted/smoked/preserved foods, and low intake of fruits and vegetables.

• Obesity, gastroesophageal reflux, and Barrett's esophagus — particularly for cardia/gastroesophageal junction cancers.

• Older age and male sex.

• Family history of gastric cancer and inherited syndromes (e.g., CDH1 hereditary diffuse gastric cancer).

• Pernicious anemia, chronic atrophic gastritis, and prior gastric ulcer.

• Race/ethnicity and geography — in the US, incidence is 1.7- to 3.9-fold higher among Black, Hispanic, Asian/Pacific Islander, American Indian, and Alaska Native individuals than among non-Hispanic White individuals (Li et al., Gastroenterology, 2023).

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How It Affects the Body

Gastric cancer begins in the innermost lining (mucosa) and, as it grows, invades progressively deeper layers of the stomach wall — submucosa, muscularis propria, and serosa — a depth of invasion captured by the "T" category of staging (NCCN Gastric Cancer Guidelines, 2026). Because the stomach wall is rich in lymphatic channels, the cancer characteristically spreads first to the regional (perigastric) lymph nodes along the arteries supplying the stomach, and later to distant sites (Li et al., JAMA Surgery, 2022). Advanced tumors can bleed (causing iron-deficiency anemia), obstruct the passage of food (causing vomiting, early satiety, and weight loss), or seed the peritoneum, a pattern especially common with diffuse-type cancers and often missed on cross-sectional imaging (Sundar et al., Lancet, 2025). The most common sites of distant spread are the liver (26%–48%), the peritoneum (32%–46%), and distant lymph nodes (11%–20%) (Patel et al., JAMA, 2026). Classic physical findings of advanced spread include a left supraclavicular node (Virchow's node) and an umbilical nodule (Sister Mary Joseph's node) (Johnston & Beckman, Current Oncology Reports, 2019).

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Complications

Complications of gastric cancer and its progression include (Patel et al., JAMA, 2026; Johnston & Beckman, Current Oncology Reports, 2019):

• Gastrointestinal bleeding and iron-deficiency anemia — anemia affects roughly 40% of patients at diagnosis.

• Gastric outlet or esophageal obstruction — causing vomiting, dysphagia, and inability to eat.

• Weight loss and malnutrition — present in the majority of symptomatic patients.

• Peritoneal carcinomatosis with malignant ascites — a common pattern of spread, particularly in diffuse-type disease.

• Distant metastasis — most often to the liver, peritoneum, and distant lymph nodes.

• Perforation, and complications related to therapy (surgery, chemotherapy, immunotherapy).

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Symptoms and Signs

• Early gastric cancer frequently causes no symptoms or only vague ones, which is why it is so often found late (Smyth et al., Lancet, 2020). In the US, more than 90% of patients are symptomatic by diagnosis, and in a large case review the most common symptoms were weight loss (62%), abdominal pain (52%), nausea (34%), poor appetite/anorexia (32%), and difficulty swallowing/dysphagia (26%); iron-deficiency anemia is present in about 40% (Patel et al., JAMA, 2026). Other common features are indigestion (dyspepsia) and early satiety; dysphagia or regurgitation suggests a proximal or gastroesophageal-junction tumor (Smyth et al., Lancet, 2020).
• Several alarm features warrant prompt endoscopy because they may signal cancer: unexplained weight loss, progressive difficulty or pain with swallowing, gastrointestinal bleeding (vomiting blood or black/tarry stools), persistent vomiting, and unexplained iron-deficiency anemia (Walter, JAMA, 2026; Patel et al., JAMA, 2026).
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Diagnosis

Diagnosis is made by upper endoscopy (EGD) with biopsy, followed by staging to determine whether treatment is curative or palliative (Sundar et al., Lancet, 2025; NCCN Gastric Cancer Guidelines, 2026). The standard workup includes:

• Upper endoscopy with multiple biopsies. Gastric cancer typically appears as a friable, ulcerated mass; because up to 5% of malignant ulcers look benign, multiple (6–8) biopsies are taken from any suspicious lesion — a single biopsy is only ~70% sensitive, rising to ~98% with seven biopsies (Xia & Aadam, Journal of Surgical Oncology, 2022; NCCN Gastric Cancer Guidelines, 2026).

• CT of the chest, abdomen, and pelvis with contrast — the primary test to detect metastatic disease in the liver, lung, or peritoneum (Patel et al., JAMA, 2026).

• Endoscopic ultrasound (EUS) — the most accurate test for depth of tumor invasion (T) and regional nodes (N), and essential when early-stage disease is suspected or endoscopic resection is being considered (NCCN Gastric Cancer Guidelines, 2026; Patel et al., JAMA, 2026).

• FDG-PET/CT — adds sensitivity for CT-occult distant metastases in patients being considered for curative surgery, though it is less reliable in diffuse/mucinous tumors (Patel et al., JAMA, 2026; Sundar et al., Lancet, 2025).

• Staging (diagnostic) laparoscopy with peritoneal washings for cytology — recommended for stage IB or higher disease planned for resection, because peritoneal spread is frequently missed on imaging (Sundar et al., Lancet, 2025; NCCN Gastric Cancer Guidelines, 2026).

• Biomarker testing — all newly diagnosed patients should have mismatch-repair (MMR)/microsatellite-instability (MSI) and PD-L1 testing, with HER2 (ERBB2) and CLDN18.2 testing added for advanced/metastatic disease, because these markers direct therapy (NCCN Gastric Cancer Guidelines, 2026; Patel et al., JAMA, 2026).

• Testing and eradication of H. pylori, and genetic/family-history assessment where indicated (NCCN Gastric Cancer Guidelines, 2026).

Stage is assigned by the AJCC/UICC TNM system (8th edition), which combines tumor depth (T), regional nodes (N), and distant metastasis (M) (Johnston & Beckman, Current Oncology Reports, 2019).

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Differential Diagnosis

Because symptoms are nonspecific, several conditions can mimic gastric cancer and should be considered — particularly before a tissue diagnosis is confirmed (Johnston & Beckman, Current Oncology Reports, 2019; Sundar et al., Lancet, 2025):

• Benign peptic ulcer disease and gastritis (including H. pylori gastritis).

• Gastroesophageal reflux disease (GERD) and functional dyspepsia.

• Gastric lymphoma (including MALT lymphoma).

• Gastrointestinal stromal tumor (GIST) and gastric neuroendocrine tumors.

• Gastric polyps and benign masses.

• Metastatic cancer to the stomach and pancreatic or esophageal/gastroesophageal-junction cancer.

• Gastroparesis and other causes of early satiety and vomiting.

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Lifestyle Modifications

Lifestyle measures are aimed at risk reduction and prevention, and complement medical and surgical treatment (Thrift et al., Nature Reviews Clinical Oncology, 2023; Walter, JAMA, 2026):

• Test for and eradicate H. pylori — the single most effective modifiable intervention, reducing gastric cancer incidence by about 46% and cancer-related mortality by about 39% (Li et al., Gastroenterology, 2023).

• Stop smoking and limit alcohol.

• Reduce salt and salted/smoked/preserved foods, and increase fresh fruits and vegetables.

• Maintain a healthy weight — obesity is a risk factor, particularly for cardia/GEJ cancers.

• Pursue appropriate endoscopic surveillance if you have precancerous changes (atrophic gastritis, intestinal metaplasia, dysplasia) or a strong family history; in high-incidence countries, endoscopic screening from age ~40 improves survival (Patel et al., JAMA, 2026).

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Treatment Options

Treatment is stage-driven and coordinated by a multidisciplinary tumor board (Patel et al., JAMA, 2026; NCCN Gastric Cancer Guidelines, 2026):

• Endoscopic resection (EMR/ESD). For very early, superficial tumors (Tis/T1a) meeting criteria, endoscopic mucosal resection or submucosal dissection can remove the cancer while preserving the stomach (NCCN Gastric Cancer Guidelines, 2026).

• Surgery (gastrectomy with D2 lymphadenectomy). Complete (R0) resection with an adequate lymph node dissection is the cornerstone of curative treatment for invasive, localized disease; minimally invasive and robotic approaches achieve comparable oncologic outcomes with faster recovery in selected patients (Li et al., JAMA Surgery, 2022; Wang et al., CA: A Cancer Journal for Clinicians, 2026). (See the Gastrectomy procedure page for full surgical detail.)

• Perioperative chemotherapy. For locally advanced, potentially resectable disease (≥cT2 and/or node-positive), the FLOT regimen (fluorouracil, leucovorin, oxaliplatin, docetaxel) before and after surgery is the NCCN-preferred standard, improving median overall survival to 50 months vs. 35 months with an older regimen (Patel et al., JAMA, 2026).

• Perioperative immunotherapy. Adding the PD-L1 inhibitor durvalumab to FLOT improved 2-year event-free survival (67.4% vs. 58.5%) in the MATTERHORN trial and is now incorporated into NCCN perioperative options; MSI-H/dMMR tumors are candidates for neoadjuvant immunotherapy (Shitara, New England Journal of Medicine, 2025; NCCN Gastric Cancer Guidelines, 2026).

• Postoperative chemoradiation. An option for patients who had less than a D2 node dissection (NCCN Gastric Cancer Guidelines, 2026).

• Systemic therapy for advanced/metastatic disease — biomarker-driven. First-line chemotherapy is combined with targeted/immunotherapy based on tumor markers: trastuzumab for HER2-positive tumors, a checkpoint inhibitor (nivolumab, pembrolizumab, or tislelizumab) for PD-L1-positive tumors, and zolbetuximab for CLDN18.2-positive/HER2-negative tumors (Patel et al., JAMA, 2026; NCCN Gastric Cancer Guidelines, 2026).

• Palliative and supportive care. Symptom-directed treatment (for bleeding, obstruction, pain), nutritional support, and early palliative care — which itself is associated with a survival benefit (Patel et al., JAMA, 2026).

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When to See a Doctor

See a physician for persistent indigestion, upper-abdominal pain or burning, early satiety, nausea, or poor appetite that does not resolve — especially in anyone over 50, or at any age with risk factors such as H. pylori infection, a family history of gastric cancer, or prior precancerous stomach changes (Walter, JAMA, 2026; Mott & Gray, American Family Physician, 2025). Endoscopy is recommended for new-onset upper-abdominal symptoms at age 50 or older, and for people of any age whose symptoms are accompanied by alarm features (Walter, JAMA, 2026).

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When to Seek Treatment

Seek prompt medical evaluation for any alarm symptoms, which require urgent endoscopy to exclude cancer (Patel et al., JAMA, 2026; Walter, JAMA, 2026):

• Unintentional weight loss

• Difficulty or pain with swallowing (dysphagia/odynophagia)

• Vomiting blood, or black/tarry stools

• Persistent vomiting or food getting stuck

• Unexplained iron-deficiency anemia

• A palpable abdominal mass or abnormal lymph node

Once a diagnosis of gastric cancer is confirmed, treatment should begin promptly after complete staging and multidisciplinary review, because outcomes are closely tied to the stage at which treatment starts (NCCN Gastric Cancer Guidelines, 2026; Patel et al., JAMA, 2026).

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Long-term Outlook

For patients treated for early-stage disease, the long-term outlook is favorable, and survival prospects improve with each disease-free year after surgery (Patel et al., JAMA, 2026). Long-term care centers on surveillance for recurrence, management of the nutritional and digestive consequences of gastrectomy (small frequent meals, lifelong vitamin B12/iron/calcium/vitamin D supplementation, and attention to dumping and bile reflux), and treatment of any precancerous changes in a remaining stomach (NCCN Gastric Cancer Guidelines, 2026). For advanced disease, the outlook is steadily improving as biomarker-driven immunotherapy and targeted agents (HER2-directed therapy, CLDN18.2-directed zolbetuximab, antibody-drug conjugates) extend survival and reshape first-line care (Wang et al., CA: A Cancer Journal for Clinicians, 2026; Patel et al., JAMA, 2026). Across the spectrum, outcomes are best when care is delivered by an experienced, high-volume multidisciplinary team.

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Prognosis

Prognosis depends overwhelmingly on the stage at diagnosis (Patel et al., JAMA, 2026). With treatment, 5-year relative survival is about 75% for stage I (localized) disease, roughly 45% median 5-year overall survival for locally advanced (stage II–III) disease treated with perioperative therapy and surgery, and under 10% for metastatic (stage IV) disease (Patel et al., JAMA, 2026). Large real-world cohorts show the same steep gradient — one nationwide analysis reported stage-specific 5-year survival of roughly 90% (stage I), 69% (stage II), 37% (stage III), and 14% (stage IV) (Zhao et al., Cancer Letters, 2026). Because most patients in Western countries present at an advanced stage, the overall survival rate remains modest, which is precisely why early detection and H. pylori eradication are so impactful (Smyth et al., Lancet, 2020; Müller & He, New England Journal of Medicine, 2023).

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Why Choose Dr. de la Cruz‑Muñoz

Gastric cancer care demands a surgeon who combines technical mastery of the stomach with the judgment to coordinate complex multimodal therapy — and outcomes in gastric surgery are strongly tied to surgeon and center experience, with D2 lymphadenectomy and minimally invasive gastrectomy achieving the safest, most durable results in dedicated, high-volume hands (Li et al., JAMA Surgery, 2022). As a board-certified surgeon with advanced expertise in minimally invasive and robotic foregut surgery, Dr. Nestor de la Cruz-Muñoz, MD, FACS, DABOM emphasizes the complete, guideline-concordant workup that modern staging requires (endoscopy with adequate biopsies, EUS, CT, PET/CT, staging laparoscopy, and full biomarker testing), an R0-oriented operative plan with meticulous lymphadenectomy, and minimally invasive technique whenever oncologically appropriate to speed recovery (NCCN Gastric Cancer Guidelines, 2026; Patel et al., JAMA, 2026). He coordinates care within the multidisciplinary team — medical oncology, radiation oncology, gastroenterology, pathology, radiology, and nutrition — that drives the best outcomes, and attends to the lifelong nutritional follow-up that determines quality of life after gastrectomy. Patients receive candid, stage-specific counseling about prognosis, treatment sequencing, and every available option.

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