Stomach cancer is cancer that occurs in the stomach — the muscular sac located in the upper middle of your abdomen, just below your ribs.
Your stomach is responsible for receiving and holding the food you eat and then helping to break down and digest it. Another term for stomach cancer is gastric cancer. These two terms most often refer to stomach cancer that begins in the mucus-producing cells on the inside lining of the stomach (adenocarcinoma). Adenocarcinoma is the most common type of stomach cancer. Stomach cancer is uncommon in the United States, and the number of people diagnosed with the disease each year is declining. Stomach cancer is much more common in other areas of the world, particularly Japan.
Doctors aren’t sure what causes stomach cancer. There is a strong correlation between a diet high in smoked, salted and pickled foods and stomach cancer. As the use of refrigeration for preserving foods has increased around the world, the rates of stomach cancer have declined.
In general, cancer begins when an error (mutation) occurs in a cell’s DNA. The mutation causes the cell to grow and divide at a rapid rate and to continue living when normal cells would die. The accumulating cancerous cells form a tumor that can invade nearby structures. And cancer cells can break off from the tumor to spread throughout the body.
Types of stomach cancer
The cells that form the tumor determine the type of stomach cancer. The type of cells in your stomach cancer helps determine your treatment options. Types of stomach cancer include:
- Cancer that begins in the glandular cells (adenocarcinoma). The glandular cells that line the inside of the stomach secrete a protective layer of mucus to shield the lining of the stomach from the acidic digestive juices. Adenocarcinoma accounts for more than 90 percent of all stomach cancers.
- Cancer that begins in immune system cells (lymphoma). The walls of the stomach contain a small number of immune system cells that can develop cancer. Lymphoma in the stomach is rare.
- Cancer that begins in hormone-producing cells (carcinoid cancer). Hormone-producing cells can develop carcinoid cancer. Carcinoid cancer is rare.
- Cancer that begins in nervous system tissues. A gastrointestinal stromal tumor (GIST) begins in specific nervous system cells found in your stomach. GIST is a very rare form of cancer.
Because the other types of stomach cancer are rare, when people use the term “stomach cancer” they generally are referring to adenocarcinoma.
Factors that increase your risk of stomach cancer include:
- A diet high in salty and smoked foods
- A diet low in fruits and vegetables
- Eating foods contaminated with aflatoxin fungus
- Family history of stomach cancer
- Infection with Helicobacter pylori
- Long-term stomach inflammation (chronic gastritis)
- Pernicious anemia
- Stomach polyps