Treatment for stomach cancer typically involves surgery to remove part or all of the stomach, often combined with chemotherapy, immunotherapy, or radiation. The specific approach depends on how far the cancer has spread. When caught early and still confined to the stomach, the five-year survival rate is about 76.5%. Once it reaches distant organs, that number drops to 7.5%, which is why the treatment plan changes significantly based on stage.
How Stomach Cancer Is Diagnosed
The process usually starts with basic tests: blood work to check for anemia (which can signal bleeding in the stomach) and stool samples to look for hidden blood. If those raise concerns, the main diagnostic tool is an upper endoscopy. A thin, lighted tube goes down your throat into your stomach, letting doctors visually inspect the lining and take small tissue samples for biopsy. Those samples are examined under a microscope to confirm whether cancer cells are present.
Once cancer is confirmed, additional imaging helps determine the stage. CT scans show whether the tumor has spread to nearby organs or lymph nodes. An endoscopic ultrasound can reveal how deep the tumor has grown into the stomach wall. In some cases, doctors perform a laparoscopy, a minor surgical procedure where a small camera is inserted through a tiny incision in the abdomen to look directly at surrounding organs and collect cell samples. This step helps rule out spread that imaging might miss.
Surgery: Partial or Total Stomach Removal
Surgery is the primary treatment when the goal is to cure the cancer. The two main options are partial gastrectomy and total gastrectomy. A partial (or subtotal) gastrectomy removes about 80% of the stomach and is used when the tumor is in the lower portion. A total gastrectomy removes the entire stomach and is necessary when the cancer is widespread within the organ or located in a position that doesn’t allow for safe partial removal.
After a partial gastrectomy, the remaining stomach is reconnected to the small intestine. After a total gastrectomy, the small intestine is attached directly to the esophagus, creating a new pathway for food. In both cases, surgeons typically remove nearby lymph nodes to check whether cancer has spread beyond the stomach wall. The number of lymph nodes removed and examined is an important factor in accurate staging.
Chemotherapy Before and After Surgery
For cancers that have grown into the deeper layers of the stomach wall or reached nearby lymph nodes, chemotherapy is commonly given both before and after surgery. The pre-surgery rounds (called neoadjuvant chemotherapy) shrink the tumor, making it easier to remove completely. Post-surgery chemotherapy targets any remaining cancer cells that imaging can’t detect.
The standard chemotherapy combination uses four drugs: fluorouracil, leucovorin, oxaliplatin, and docetaxel, given in cycles every two weeks. This regimen has proven effective for both operable and advanced stomach cancers. The drugs work by disrupting the ability of cancer cells to grow and divide. Side effects vary but commonly include fatigue, nausea, and increased vulnerability to infections.
Immunotherapy and Targeted Therapy
Not all stomach cancers are alike at the molecular level, and treatment increasingly depends on the specific characteristics of your tumor. Two biomarkers matter most: HER2 status and PD-L1 expression. Your biopsy tissue is tested for both.
About 15-20% of stomach cancers are HER2-positive, meaning the cancer cells have an excess of a protein that fuels their growth. These tumors respond to trastuzumab, a drug that blocks the HER2 protein. For HER2-positive tumors that also express PD-L1 (a marker found on about 85% of HER2-positive cases in clinical trials), the FDA approved a combination of trastuzumab, pembrolizumab (an immunotherapy drug), and chemotherapy as a first-line treatment in 2025. Pembrolizumab works by helping your immune system recognize and attack cancer cells that would otherwise evade detection.
For HER2-negative tumors, current guidelines recommend adding an immunotherapy drug to standard chemotherapy when PD-L1 levels are elevated. The specific immunotherapy drug and the threshold for PD-L1 expression vary slightly between guidelines, but the principle is the same: immunotherapy boosts the effectiveness of chemotherapy in cancers with the right molecular profile. A newer option for a subset of HER2-negative tumors targets a protein called claudin 18.2, offering an additional avenue for patients whose cancers carry that marker.
Radiation Therapy
Radiation plays a more limited role in stomach cancer compared to surgery and chemotherapy. When used, it’s external beam radiation, delivered by a machine that aims high-energy X-rays at the tumor area from outside the body. Radiation is most often given after surgery alongside chemotherapy to reduce the risk of the cancer returning locally. It’s particularly useful when the surgical margins were close, meaning the cancer extended near the edge of the removed tissue. Radiation combined with chemotherapy before surgery is also being studied as a way to shrink tumors.
Treatment for Advanced or Metastatic Cancer
When stomach cancer has spread to distant organs (the situation for about 36% of patients at diagnosis), surgery to cure the cancer is no longer possible. Treatment shifts to controlling the disease and maintaining quality of life. The combination of chemotherapy with immunotherapy or targeted therapy forms the backbone of treatment, as described above, with the specific regimen chosen based on biomarker testing.
For patients whose tumor is blocking the passage of food through the stomach or into the intestines, endoscopic stenting can restore the ability to eat and drink. A small expandable tube is placed inside the blocked area during an endoscopy, holding it open without requiring major surgery. This approach allows faster return to eating compared to surgical bypass and carries less risk for patients with limited life expectancy. In cases of bowel obstruction further along the digestive tract, stenting can serve as an alternative to more invasive procedures.
Life After Stomach Surgery
Losing part or all of your stomach requires permanent changes to how you eat. The most immediate challenge is that your body can no longer hold or process large meals. You’ll need to eat six to eight small meals per day, focusing on high-calorie, high-protein foods every one to two hours. Drinking fluids should be separated from eating by at least 30 minutes, and you should aim for at least 64 ounces of fluid daily between meals.
Dumping syndrome is one of the most common complications. It happens when food, especially sugary or carbohydrate-heavy food, moves too quickly from the stomach (or the esophageal connection) into the small intestine. Early dumping causes nausea, cramping, and diarrhea within 30 minutes of eating. Late dumping, which hits one to three hours later, causes lightheadedness and sweating as your blood sugar drops. You can prevent both by avoiding added sugars, always pairing carbohydrates with protein, eating slowly, and chewing thoroughly.
After a total gastrectomy, you’re at high risk for deficiencies in iron, vitamin B12, thiamine, folate, zinc, calcium, and fat-soluble vitamins (A, D, E, and K). Standard multivitamins aren’t sufficient. Specially formulated bariatric vitamins deliver B12 in a form that can be absorbed without stomach acid, eliminating the need for B12 injections when taken daily. Calcium must be taken as calcium citrate (the only form absorbable without stomach acid) and spaced at least two hours apart from iron supplements, since iron blocks calcium absorption. Skipping these supplements leads to problems like anemia, hair loss, and bone density loss.
Survival by Stage
Five-year survival rates for stomach cancer vary dramatically depending on how far the disease has progressed at diagnosis. For localized cancer (still confined to the stomach), the five-year survival rate is 76.5%, and this group represents about 31% of cases. Regional cancer that has spread to nearby lymph nodes, making up 24% of diagnoses, has a 37.2% five-year survival rate. Distant cancer, which accounts for 36% of cases, has a 7.5% five-year survival rate. About 10% of cases are diagnosed at an unknown stage, with a survival rate of 31.9%.
People at particularly high risk, including those with a first-degree relative who had stomach cancer or those carrying genetic conditions like hereditary diffuse gastric cancer, Lynch syndrome, or Li-Fraumeni syndrome, may be eligible for screening programs or even preventive surgery. If stomach cancer runs in your family, genetic counseling can help determine whether you carry a mutation that warrants closer monitoring.