Gastric (Stomach) Cancer
Gastric (stomach) cancer, as defined by the National Cancer Institute (NCI), is cancer that forms in tissues lining the stomach. Located in the upper abdomen between the esophagus and small intestine, the stomach serves as a reservoir where food is stored and partially digested after it is eaten. When food enters the stomach from the esophagus, the stomach churns the food and releases digestive juices to process the food before it enters the small intestine.
Gastric cancer occurs when cells in the stomach become abnormal and multiply. The majority (90-95%) of gastric cancers are adenocarcinomas, meaning that they arise from the mucosal tissue lining the inside of the stomach. The abnormal cells may spread over time to invade deeper into the stomach wall, or eventually spread to nearby tissues or organs. Adenocarcinomas of the stomach can be further classified as intestinal type or diffuse type, based on how the cells look under a microscope.
Some of the factors that may increase the risk for development of gastric cancer include: Age over 55, male gender, ethnicity, smoking, family history of stomach cancer, eating smoked, salted, or pickled foods, and the bacterial infection Helicobacter pylori. H. pylori is a common, treatable infection which leads to stomach inflammation and may increase the risk of developing gastric cancer. In the United States, gastric cancer is more common in Asians or Pacific Islanders, Hispanic Americans, and African Americans than in non-Hispanic whites. Learn more about Prevention & Risk Reducing Facts.
In the United States, 24,590 new cases of gastric cancer were estimated for 2015, with over 10,000 estimated deaths from gastric cancer. Although the incidence has declined over time in the U.S., gastric cancer still remains the second leading cause of cancer deaths worldwide. The lifetime risk of developing gastric cancer is approximately 1 in 111, with a slightly higher risk in men than women.
Stomach cancer may or may not present with vague gastrointestinal symptoms, including indigestion, abdominal pain or discomfort, nausea and vomiting, bloating, or the feeling of fullness when eating a meal (also called early satiety). These symptoms can also be associated with other gastrointestinal illnesses, however, and should be discussed with a doctor who can perform tests to determine the cause of the symptoms.
Lab tests may be normal with gastric cancer, or there may be signs of anemia (low red blood cells). The best way to diagnose gastric cancer is by taking a sample of stomach tissue (biopsy). To do this, a gastroenterologist uses a small camera called an endoscope to look inside the stomach and take biopsy samples. The samples are then sent to a pathologist, who can look at them under a microscope to determine if the cells are cancerous. Other tests that may be performed to look for cancer include endoscopic ultrasound, barium swallow, CT scan, MRI, or PET scan.
Gastric adenocarcinoma can be staged based on the TNM system. This system takes into account the extent of the primary tumor, lymph node involvement, and metastasis, or spread of the cancer to other parts of the body. The five stages range from Stage 0 to Stage IV based on each of the three categories, with stage IV being cancer that has spread to distant parts of the body.
Gastric cancer is treated with surgery, chemotherapy, radiation, or a combination of these. Surgical options depend on the extent of the cancer within the stomach, and include partial or total gastrectomy (removal of the stomach). Radiation and chemotherapy may be used before or after surgery to target the growing cancer cells in the stomach. Two medications commonly used for chemotherapy in gastric cancer patients include Fluorouracil (5-FU) and cisplatin (Platinol). In advanced cases of gastric cancer, surgery or chemotherapy may be used to alleviate symptoms. This is known as supportive care or palliative care.
The 5-year survival rate for people diagnosed with stage IV gastric cancer is only 4% and the overall 5-year survival rate is 29%. This number is low because most cases are detected at a late stage, when the cancer has already spread outside the stomach. However, cases that are detected at earlier stages have a better prognosis.
Although the National Cancer Institute spends approximately 11 million to 12 million dollars annually on gastric cancer research, this is less than 0.5% of the total NCI budget. However, many medical centers develop clinical trials to learn more about prevention and treatment of gastric cancer.
1) American Cancer Society: Cancer Facts & Figures 2010
2) National Cancer Institute: A Snapshot of Stomach (Gastric) Cancer