According to the American Cancer Society, an estimated 24,590 new cases of stomach cancer were diagnosed in this country in 2015. Most cases are in people over age 65.
Stomach cancer, also called gastric cancer, has become much less common in the United States and Europe over the past 60 years. While the rates of stomach cancer in general are declining, cancers in the area of the stomach near where it joins the esophagus are increasing.
While stomach cancer is becoming less common in this country, it is the second leading cause of cancer death in much of the rest of the world, especially Japan, Eastern Europe, South America and parts of the Middle East. This may be due to differences in diet, the rate of infection with Helicobacter pylori (a type of bacteria) and the environment.
Stomach Cancer Anatomy
Many times, people refer to the abdomen, the area between the hips and chest, as the stomach. But in medical terms, the word stomach refers only to the organ.
The stomach, a J-shaped organ, is in the upper abdomen. After you chew and swallow food, it moves through a hollow tube called the esophagus into the stomach. The stomach mixes the food with gastric juices and begins digestion of the food.
The lining of the stomach has three main layers:
- Mucosal (inner)
- Muscularis (middle)
- Serosal (outer)
Generally, stomach cancer starts when cells in the mucosal layer change. Sometimes these changes develop into cancer, but most times they do not. Stomach cancer usually grows slowly and may not show symptoms for many years.
Types of Stomach Cancer
Most stomach cancers are adenocarcinomas, which develop in the cells of the mucosa. However, stomach cancer can develop anywhere in the organ and spread to other parts of the body by growing beyond the stomach wall, entering the bloodstream or reaching the lymphatic system.
The other types of cancer found in the stomach are considered rare. They include:
- Lymphoma, which affects a body’s immune system
- Gastrointestinal stromal tumors, often called GIST or gastric sarcomas
- Carcinoid tumors, which affect the hormone-producing cells of the stomach
Stomach Cancer Risk Factors
Although the exact cause of stomach cancer is not known, certain factors seem to increase your risk of developing the disease. These include:
- Eating foods preserved through pickling, salting and drying or that contain nitrates
- Eating foods that have not been stored or prepared correctly
- Obesity: Men who are obese have a higher risk of cancer in the part of the stomach nearest the esophagus.
- Infection with Helicobacter pylori: This type of bacteria, or germ, is a common cause of ulcers and may cause chronic inflammation in the stomach lining. This sometimes develops into pre-cancerous changes and cancer.
- Tobacco and alcohol abuse: Smoking and drinking excessive amounts of alcohol appear to increase the likelihood of cancer in the upper part of the stomach. Some studies have shown that smoking doubles the risk of stomach cancer.
Family history. If close relatives have any of the following conditions, you may be at a higher risk of stomach cancer:
- Stomach cancer
- Hereditary non-polyposis colon cancer (HNPCC)
- Li-Fraumeni syndrome
Having any of the following medical conditions:
- Pernicious anemia
- Chronic stomach inflammation and intestinal polyps
- Menetrier disease
- Epstein-Barr virus
- Acid reflux or chronic indigestion
- Stomach lymphoma
- Type A blood
- Prior stomach surgery
Other factors include:
- Gender: The majority of stomach cancer patients are male.
- Age: Most individuals who develop stomach cancer are older than 55.
- Ethnicity: In the United States, stomach cancer occurs more often in Hispanic Americans and African Americans than in non-Hispanic whites. It is found most in Asian/Pacific Islanders.
- Working in the rubber, metal, coal and timber industries, as well as those who have been exposed to asbestos fibers, have a higher risk for stomach cancer
- Geography: More people in Japan, China, Southern and Eastern Europe, and Central and South America develop stomach cancer than those in Northern and Western Africa, South Central Asia and North America.
Not everyone with risk factors gets stomach cancer. However, if you have risk factors, you should discuss them with your doctor.
Behavioral and lifestyle changes can help prevent stomach cancer. Visit our prevention and screening section to learn how to manage your risk.
In rare cases, stomach cancer can be passed down from one generation to the next. Genetic counseling may be right for you. Visit our genetic testing page to learn more.