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Stomach Cancer

Last Updated: Mar 1, 2019


Stomach cancer (also referred to as gastric cancer) is cancer of the stomach. Cancer occurs when normal cells lose their ability to self-regulate and grow into an abnormal mass, or tumor. Unlike benign tumors, which are not life threatening, cancerous (or malignant) tumors can invade neighboring tissues, or spread to distant organs (metastasize) via the body’s circulatory system. Patient prognosis is highly dependent on the extent of cancer spread at the time of diagnosis.

The stomach wall consists of five layers: mucosa, submucosa, muscle, subserosa, and serosa. Stomach cancer usually originates in the mucus-producing cells of the innermost layer, where it is called adenocarcinoma - the most common of stomach cancers. Other types of stomach cancers originate in immune cells (lymphomas), endocrine cells (carcinoids), or rarely, cells of the nervous system (gastrointestinal stromal tumor).

Stomach cancer is a leading cause of cancer-related deaths worldwide. In the United States, roughly 22,220 new cases of stomach cancer are expected in 2014.

Causes and Risk Factors

The underlying cause of all cancers is an error (or mutation) in the cell’s DNA that alters the function of the affected gene. It is common for genomes of cancer cells to accumulate a number of mutations as they proliferate. Certain gene mutations impair the regulatory mechanisms that control cell number and survival, allowing uncontrolled cell proliferation. Although the exact mechanism behind disease onset is not clear, the following risk factors are associated with stomach cancer:

Stomach cross-section showing the mucosa layer


As stomach cancer grows it can produce the following symptoms:

Diagnosis and Treatment

In patients experiencing symptoms, stomach cancer is diagnosed using techniques that visualize the gastrointestinal (GI) tract, and remove samples for testing.

Following a positive diagnosis, the cancer is “staged” to determine the extent of spreading within the stomach, and to other organs. Staging requires a close examination of the stomach and other organs using imaging techniques and surgery. Specific laboratory tests are also performed to assess blood counts and key bodily functions.

The stages of adenocarcinoma range from 1-4 (represented as Roman numerals I-IV). Stage 0 indicates the cancer is confined to the inner mucus lining of the stomach.

The choice of treatment is highly dependent on tumor size and location, disease stage, and extent of metastasis. In general, cancer treatment involves killing and/or removing the cancerous cells. Early-stage cancer has the highest chance of a favorable prognosis. The 5-year survival rates for stomach cancer range from 71% (stages I) to 4% (stage IV). Many patients live longer than 5 years or are cured.


The risks of developing stomach cancer may be reduced by not smoking; maintaining a heathy weight; and adhering to a diet that is high in fruits and vegetables, but low in salty, pickled, and smoked foods. Individuals with a family history of stomach cancer may consult their doctor regarding screening options for early detection.


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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.