What Is Stomach Cancer?

Stomach (gastric) cancer is cancer that starts in the cells lining the stomach. The stomach is an organ on the left side of the upper abdomen that digests food. The stomach is part of the digestive tract, a series of hollow, muscular organs joined in a long, twisting tube from the mouth to the anus. The digestive tract processes nutrients in foods that are eaten and helps pass waste material out of the body:

• Food moves from the throat to the stomach through a tube called the esophagus.
• After food enters the stomach, it is broken down by stomach muscles that mix the food and liquid with digestive juices.
• After leaving the stomach, partly digested food passes into the small intestine and then into the large intestine.
• The end of the large intestine, called the rectum, stores the waste from the digested food until it is pushed out of the anus during a bowel movement.
• Types of stomach cancer

  Adenocarcinoma of the stomach begins in the mucus-producing cells in the innermost lining of the stomach. Nearly all stomach cancers are adenocarcinomas.

  Adenocarcinoma of the stomach is divided into two main classes, depending on where it forms in the stomach:

  • Gastric cardia cancer begins in the top inch of the stomach, just below where it meets the esophagus. Most adenocarcinomas are found in the gastric cardia.
  • Non-cardia gastric cancer is cancer that begins in all other sections of the stomach.

  Adenocarcinoma of the stomach also may be described as intestinal or diffuse, depending on how the cells look under a microscope:

  • Intestinal adenocarcinomas are well differentiated, meaning the cancer cells look similar to normal cells under a microscope.
  • Diffuse adenocarcinomas are undifferentiated or poorly differentiated, meaning the cancer cells look different from normal cells under a microscope. Diffuse adenocarcinomas tend to grow and spread more quickly than the intestinal type and be harder to treat.Stomach Cancer Causes and Risk Factors

    Stomach cancer is caused by certain changes to the way stomach cells function, especially how they grow and divide into new cells. There are many risk factors for stomach cancer, but many do not directly cause cancer. Instead, they increase the chance of DNA damage in cells that may lead to stomach cancer. To learn more about how cancer develops, see What Is Cancer?.

    A risk factor is anything that increases the chance of getting a disease. Some risk factors for stomach cancer, like tobacco use, can be changed. However, risk factors also include things people cannot change, like their age and family history. Learning about risk factors for stomach cancer is important because it can help you make choices that might prevent or lower your risk of getting it.

    Who gets stomach cancer

    Stomach cancer is the fifth most common cancer worldwide. It is more common in countries in East Asia, Eastern Europe, and South and Central America than in the United States and other Western countries.

    Anyone can get stomach cancer. In the United States, the disease occurs more often among Black, Hispanic, Asian/Pacific Islander, and American Indian/Alaska Native individuals than among White individuals. Males are nearly twice as likely as females to be diagnosed with stomach cancer, and Black males are nearly twice as likely as White males to die of it. In recent years, stomach cancer rates have been increasing in younger females, particularly among Hispanic females. Stomach cancer can be diagnosed at any age, but the risk increases as a person gets older.

    Risk factors for stomach cancer

    There are several risk factors for stomach cancer. Different risk factors may increase the risk of cancer in different parts of the stomach. For example, Helicobacter pylori (H. pylori) infection increases the risk of cancer in the lower and middle part of the stomach, while obesity and gastroesophageal reflux disease (GERD) increase the risk of cancer in the upper stomach.