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.

Signs and symptoms of stomach cancer may include:

• Fatigue
• Feeling bloated after eating
• Feeling full after eating little
• Heartburn
• Indigestion
• Nausea
• Stomach pain
• Vomiting
• Weight los

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
• Smoking
• Stomach polyps

Your treatment options for stomach cancer depend on the stage of your cancer, your overall health and your preferences. Treatment for the adenocarcinoma type of stomach cancer may include:

Surgery
The goal of surgery is to remove all of the stomach cancer and a margin of healthy tissue, when possible. Options include:

• Removing early-stage tumors from the stomach lining. Very small cancers limited to the inside lining of the stomach may be removed using endoscopy. The endoscope is a lighted tube with a camera that's passed down your throat into your stomach. The doctor uses special tools to remove the cancer and a margin of healthy tissue.
• Removing a portion of the stomach (subtotal gastrectomy). During subtotal gastrectomy, the surgeon removes only the portion of the stomach affected by cancer.
• Removing the entire stomach (total gastrectomy). Total gastrectomy involves removing the entire stomach and some surrounding tissue. The esophagus is then connected directly to the small intestine to allow food to move through your digestive system.
• Removing lymph nodes to look for cancer. The surgeon examines and removes lymph nodes in your abdomen to look for cancer cells.
• Surgery to relieve signs and symptoms. Removing part of the stomach may relieve signs and symptoms of a growing tumor in people with advanced stomach cancer. In this case, surgery can't cure stomach cancer, but it can make you more comfortable.

Surgery carries a risk of bleeding and infection. If all or part of your stomach is removed, you may experience digestive problems, such as diarrhea, vomiting and dumping syndrome, which occurs when the small intestine fills too quickly with undigested food.

Radiation therapy
Radiation therapy uses high-powered beams of energy to kill cancer cells. The energy beams come from a machine that moves around you as you lie on a table.

Radiation therapy can be used before surgery (neoadjuvant radiation) to shrink a stomach tumor so it's more easily removed. Radiation therapy can also be used after surgery (adjuvant radiation) to kill any cancer cells that might remain around your stomach. Radiation is often combined with chemotherapy. In cases of advanced cancer, radiation therapy may be used to relieve side effects caused by a large tumor.

Radiation therapy to your stomach can cause diarrhea, indigestion, nausea and vomiting.

Chemotherapy
Chemotherapy is a drug treatment that uses chemicals to kill cancer cells. Chemotherapy drugs travel throughout your body, killing cancer cells that may have spread beyond the stomach.

Chemotherapy can be given before surgery (neoadjuvant chemotherapy) to help shrink a tumor so it can be more easily removed. Chemotherapy is also used after surgery (adjuvant chemotherapy) to kill any cancer cells that might remain in the body. Chemotherapy is often combined with radiation therapy. Chemotherapy may be used alone in people with advanced stomach cancer to help relieve signs and symptoms.

Chemotherapy side effects depend on which drugs are used. The type of stomach cancer you have determines which chemotherapy drugs you'll receive.

Clinical trials
Clinical trials are studies of new treatments and new ways of using existing treatments. Participating in a clinical trial may give you a chance to try the latest treatments. But clinical trials can't guarantee a cure. In some cases, researchers might not be certain of a new treatment's side effects.