Stomach Cancer

Upper Endoscopy (EGD) and Biopsy

Esophagogastroduodenoscopy (EGD), also called upper endoscopy, uses a thin, flexible tube with a camera to examine the lining of the esophagus, stomach, and first part of the small intestine. During the procedure, a gastroenterologist can identify suspicious areas and obtain tissue samples for examination by a pathologist. A biopsy is necessary to confirm most stomach cancer diagnoses and determine the type of tumor. Tissue may also be evaluated for H. pylori infection and molecular biomarkers that could influence treatment decisions.

Endoscopic Ultrasound (EUS)

Endoscopic ultrasound combines an endoscope with a small ultrasound probe to create detailed images of the stomach wall and surrounding structures. It is particularly useful in selected patients with potentially localized disease because it can help determine how deeply a tumor has invaded and whether nearby lymph nodes appear abnormal. EUS may also guide needle sampling when additional tissue is required.

Computed Tomography (CT)

CT scanning produces detailed cross-sectional images of the body and is commonly used after a stomach cancer diagnosis to evaluate disease extent. Imaging of the chest, abdomen, and pelvis may identify enlarged lymph nodes, involvement of nearby structures, or suspected spread to organs such as the liver. CT findings help determine whether surgery may be appropriate and whether additional staging procedures are needed.

Staging Laparoscopy

For selected patients with potentially resectable but more extensive stomach cancer, staging laparoscopy may be performed before definitive surgery. Through small abdominal incisions, a surgeon uses a camera to examine the abdominal cavity for cancer deposits that may not appear on conventional imaging. Fluid may also be collected through peritoneal washings to check for microscopic cancer cells. These findings can significantly affect treatment recommendations.

Additional Imaging and Laboratory Tests

Other tests may be used selectively. PET/CT can help investigate suspected cancer spread in certain patients, although some stomach cancers, particularly diffuse-type tumors, may not show strong PET activity. An upper GI series using swallowed barium can reveal structural abnormalities but is not generally preferred over endoscopy for diagnosing stomach cancer. Blood tests can identify anemia and evaluate organ function, while stool testing may detect hidden gastrointestinal bleeding. These tests support evaluation but do not independently establish a stomach cancer diagnosis.

Understanding the TNM System

T — Primary Tumor: Describes how deeply the cancer has grown into the layers of the stomach wall or whether it extends into nearby structures.

N — Regional Lymph Nodes: Describes the extent of cancer involvement in nearby lymph nodes. The number of involved lymph nodes helps determine the stage.

M — Distant Metastasis: Indicates whether cancer has spread to distant sites, including the liver, peritoneum, or distant lymph nodes.

Stage 0 — Carcinoma in Situ

Stage 0 refers to abnormal cells confined to the innermost lining of the stomach without invasion into deeper tissues. These changes may be identified during endoscopy and, in selected cases, treated with endoscopic removal.

Stage I — Early Invasive Cancer

Stage I generally describes cancer that has invaded the stomach wall but remains relatively limited in extent, with no or limited nearby lymph node involvement, depending on tumor depth. Some very early cancers may be suitable for endoscopic treatment, while others require surgery and lymph node evaluation.

Stage II — More Extensive Local Disease

Stage II includes certain combinations of deeper invasion into the stomach wall and regional lymph node involvement. Although the cancer has not spread to distant organs, treatment often involves surgery combined with systemic therapy, depending on the patient’s clinical stage and other factors.

Stage III — Locally Advanced Cancer

Stage III generally indicates more extensive involvement of the stomach wall, nearby structures, or regional lymph nodes, without distant metastasis. Treatment may include chemotherapy before and after surgery, with other approaches considered according to tumor characteristics and whether complete surgical removal is feasible.

Stage IV — Metastatic Stomach Cancer

Stage IV means stomach cancer has spread to distant organs or tissues. Common sites include the liver, peritoneum, and distant lymph nodes. Treatment generally focuses on systemic therapies selected according to cancer characteristics, molecular biomarkers, and patient needs, together with supportive care. Local procedures may also help manage bleeding, obstruction, or other symptoms.

Helicobacter pylori Infection

Chronic infection with Helicobacter pylori (H. pylori) is a major established risk factor for non-cardia gastric adenocarcinoma. The bacterium can produce long-standing inflammation of the stomach lining, which in some individuals leads to atrophic gastritis and precancerous changes. Most infected people do not develop stomach cancer, but identifying and treating the infection can reduce risk. Treatment typically involves a combination of antibiotics and acid-suppressing medication, followed by testing to confirm successful eradication.

Age, Sex, and Population Risk

Stomach cancer becomes more common with age and is diagnosed more frequently in men than women. In the United States, incidence also differs among population groups, reflecting a complex combination of H. pylori prevalence, geographic ancestry, environmental exposures, socioeconomic conditions, and access to preventive healthcare. These differences should be interpreted as population-level patterns rather than evidence that race itself causes stomach cancer.

Smoking, Diet, and Body Weight

Tobacco smoking increases stomach cancer risk and is a preventable contributor to several gastrointestinal cancers. Diets high in heavily salted or salt-preserved foods are also associated with increased risk, while diets that include a variety of fruits and vegetables may contribute to better overall health. Obesity is particularly associated with cancers near the upper stomach and gastroesophageal junction. Reducing tobacco exposure and maintaining healthy dietary and activity patterns can support cancer risk reduction, although no single food or lifestyle change eliminates the possibility of stomach cancer.

Chronic Gastritis and Other Stomach Conditions

Chronic atrophic gastritis and intestinal metaplasia are changes in the stomach lining associated with increased cancer risk in certain patients. Autoimmune gastritis, sometimes associated with pernicious anemia and vitamin B12 deficiency, is another recognized risk factor. Patients with these conditions may benefit from individualized discussion about H. pylori testing, endoscopic evaluation, and whether surveillance is appropriate.

Family History and Inherited Cancer Syndromes

Having a first-degree relative with stomach cancer can increase personal risk. A smaller proportion of gastric cancers are associated with inherited genetic syndromes, including hereditary diffuse gastric cancer involving CDH1 or CTNNA1, Lynch syndrome, and certain polyposis syndromes. CDH1-related hereditary diffuse gastric cancer is particularly important because affected families may also have an increased risk of lobular breast cancer.

Individuals with multiple relatives diagnosed with stomach cancer, stomach cancer at unusually young ages, or a family pattern suggestive of hereditary cancer may benefit from genetic counseling. Testing and surveillance recommendations depend on the specific family history and any identified inherited mutation.

Endoscopic Treatment for Early Stomach Cancer

Selected very early-stage stomach cancers that are confined to superficial layers and have a low risk of lymph node involvement may be removed during endoscopy. Techniques such as endoscopic submucosal dissection (ESD) allow specialists to remove certain lesions without removing part of the stomach. Careful evaluation of tumor size, depth, appearance, and pathology helps determine whether endoscopic treatment is appropriate or whether additional surgery is necessary.

Partial or Subtotal Gastrectomy

Partial gastrectomy removes the portion of the stomach containing the cancer along with appropriate nearby lymph nodes. The remaining stomach is then connected to the digestive tract to restore the passage of food. This procedure may be considered when the tumor’s location and extent allow an adequate surgical margin while preserving part of the stomach. Patients may need to adjust eating habits and nutritional intake during recovery.

Total Gastrectomy

Total gastrectomy involves removal of the entire stomach, usually with regional lymph nodes, followed by reconstruction that connects the esophagus to the small intestine. It may be needed when a tumor involves a large portion of the stomach or is located where partial removal would not provide adequate cancer clearance. Recovery requires important long-term nutritional adjustments, including smaller, more frequent meals and monitoring for deficiencies. Lifelong vitamin B12 supplementation is generally required after total gastrectomy.

Minimally Invasive and Robot-Assisted Surgery

Some stomach cancer operations can be performed using laparoscopic or robot-assisted techniques through smaller incisions. These approaches may reduce certain postoperative burdens and facilitate recovery for appropriately selected patients. However, the choice between minimally invasive and open surgery depends on cancer extent, the complexity of reconstruction, patient factors, and the ability to safely achieve complete tumor removal and appropriate lymph node evaluation.

Chemotherapy and Systemic Treatment

Chemotherapy uses medications that circulate throughout the body to treat cancer cells. For many patients with localized but more advanced gastric adenocarcinoma, chemotherapy may be recommended before and after surgery, an approach called perioperative chemotherapy. Regimens such as FLOT may be considered for eligible patients. For unresectable or metastatic disease, chemotherapy may form the foundation of treatment and can be combined with other medications depending on tumor biology and the patient’s condition.

Radiation Therapy

Radiation therapy uses focused high-energy treatment to damage cancer cells. It may be recommended in selected circumstances, including certain postoperative situations or when treatment is needed to control bleeding, pain, or obstruction. Radiation may also be combined with chemotherapy for some patients. Its role is determined by the tumor’s location, prior treatment, and individual clinical circumstances rather than being routinely necessary for every stomach cancer diagnosis.

Targeted Therapy and Immunotherapy

Molecular and biomarker testing can identify specific characteristics of stomach cancer that may guide treatment, particularly when the disease is advanced or metastatic. Important biomarkers include HER2, PD-L1, mismatch repair deficiency or microsatellite instability (dMMR/MSI-H), and CLDN18.2. Depending on the findings, selected patients may benefit from HER2-directed therapies, immune checkpoint inhibitors, or other targeted treatments combined with chemotherapy. These medications are not appropriate for every tumor, making individualized molecular evaluation an important part of treatment planning.

Supportive Care and Clinical Trials

Nutrition and symptom management are essential components of stomach cancer care, particularly for patients experiencing weight loss, difficulty eating, anemia, or changes in digestion after treatment. Supportive care may involve nutrition specialists, pain management, psychosocial services, and procedures to address bleeding or obstruction. Clinical trials may also provide opportunities to consider investigational treatments when an appropriate study is available and eligibility requirements are met.