Types of Stomach Cancer

April 28, 2025

This page was reviewed under our medical and editorial policy by Yanghee Woo, M.D., associate professor, Division of Surgical Oncology, Department of Surgery, City of Hope^® Orange County Lennar Foundation Cancer Center.

There are several different types of stomach cancer, defined by the specific cells in which the cancer begins. Most stomach cancers are adenocarcinomas, but there are a handful of other types that may develop.

Different forms of stomach cancer have distinct treatment approaches.

Gastric Adenocarcinoma

This is by far the most common form of stomach cancer, accounting for 90 to 95% of all cases. Adenocarcinomas begin in the gland cells forming the stomach’s innermost lining (mucosa).

Gastric adenocarcinomas are divided into two types.

Intestinal type: This cancer usually develops in the lower portions of the stomach, and many cases are thought to arise due to chronic inflammation in the stomach lining. There is a strong association between this cancer type and infection with H. pylori, a type of bacteria that may damage the stomach lining and cause ulcers. Intestinal-type adenocarcinomas also tend to have certain genetic changes that might make them treatable with targeted drugs (drugs designed to recognize specific abnormalities in cancer cells).

Diffuse type: This less common form of adenocarcinoma tends to grow more quickly than the intestinal type. It’s more difficult to diagnose and may be harder to treat. It is called diffuse because the cancer cells are scattered throughout the stomach, rather than clumped together in the form of a tumor. Instead of creating a distinct mass that may be easily identified by endoscopy or seen on a CT scan, the cancer cells may be hiding underneath the mucosal layer or appear as thickened stomach wall. Some cases of diffuse-type stomach cancer are caused by inherited genetic mutations.

Less Common Stomach Cancer Types

Some less common stomach cancer types include the following.

Gastrointestinal stromal tumor (GIST): This is an uncommon cancer, with about 4,000 to 6,000 Americans diagnosed with the disease each year. GISTs develop from special cells called the interstitial cells of Cajal and may begin anywhere in the gastrointestinal tract where these cells exist. Most cases, though, arise in the stomach. Most GISTs grow slowly and are curable with surgery when diagnosed before the cancer has spread to distant sites in the body. Larger-sized GISTs that have not spread to other organs are often treatable with surgery and special oral medications that may either shrink the tumor before surgery or decrease its risk of recurrence after surgery.

Neuroendocrine (carcinoid) tumors: These rare cancers begin in the stomach lining in certain hormone-making cells. There are three types of carcinoid tumors of the stomach. Most are type 1 and are typically slow-growing. Types 2 and 3 are more aggressive. Certain genetic syndromes and diseases that reduce the amount of acid the stomach produces, such as atrophic gastritis, may raise the risk of developing this type of cancer.

Gastric lymphoma: Lymphomas are cancers that form in immune system cells called lymphocytes. Most lymphomas arise elsewhere in the body, but some begin in the stomach wall, with some cases linked to infection with H. pylori bacteria.

Other cancers: Rarely, certain other cancers — such as squamous cell carcinomas, small cell carcinomas and leiomyosarcomas — begin in the stomach.