What Are the Different Types of Stomach Cancer?

When you receive a stomach (or gastric) cancer diagnosis, the emotional weight of the news can be overwhelming. Coping with these emotions can be challenging, especially as doctors and healthcare professionals are providing a lot of new information. It is important to take the time to learn more about the type of gastric cancer you have been diagnosed with. By learning more, you can also make informed decisions about your care. Knowing what to expect can help you prepare for the road ahead, mentally, physically and emotionally. It may also give you a sense of control over your situation, which can be a powerful tool as you navigate through this journey.

Gastric cancers are classified based on the type of tissue the malignant (cancerous) cells originate from. Before we jump into the specifics, it helps to know the structure and function of the stomach.

Adenocarcinomas

The most common type of gastric cancer is adenocarcinomas, which account for 90–95% of all cases. Gastric adenocarcinomas start in the gland cells of the innermost layer of the stomach wall, known as the mucosa.

There are two main types of gastric adenocarcinomas, according to the Lauren classification:

This image may contain content that could be offensive or disturbing to some individuals. Tap to reveal the image.

• Intestinal: Intestinal gastric adenocarcinomas are characterized by tumor cells that stick close to each other, and tubular or glandular structures. They occur most commonly in men and the elderly, and are frequently associated with Helicobacter pylori infection and spread to the lymph nodes and blood vessels. Additionally, they are known to develop after the worsening of gastritis (long-term inflammation and damage of the stomach lining).

This image may contain content that could be offensive or disturbing to some individuals. Tap to reveal the image.

• Diffuse: Diffuse-type gastric adenocarcinomas tend to affect a larger area of the stomach rather than being restricted to a single section. Their cells tend to be loosely arranged, and lack cell adhesion. The tumor cells most commonly seen are the “signet-ring cells”, which grow rapidly with the potential to invade the deeper layers of the stomach wall, making it thicker and rigid. Notably, younger individuals with a family history of gastric cancer or related genetic syndromes, such as hereditary diffuse gastric cancer, have an increased risk of developing this disease.

Read more: All About Gastric Adenocarcinomas

Gastrointestinal stromal tumors (GISTs)

GISTs are a rare type of soft tissue sarcoma — a general term for cancers beginning in connective tissues surrounding and protecting organs of the body. Most tumors begin in the interstitial cells of Cajal found in the muscularis propria layer of the stomach wall. Known as the ‘pacemaker’ cells of the gut, these cells are responsible for sending signals to trigger muscular contractions that move stomach contents along the digestive tract (peristalsis).

GISTs can be benign (non-cancerous) or malignant. Some tumors, especially larger ones, are more likely to spread to other organs and tissues.

Learn more: The GIST of stomach GISTs

Neuroendocrine tumors

Gastric neuroendocrine tumors (NETs) are an uncommon type of cancer that starts in the neuroendocrine cells of the stomach. These cells produce hormones controlling the release of gastric juices and how quickly food moves through the stomach.

Read more: Understanding Gastric Neuroendocrine Tumors

Lymphomas

Lymphomas are cancers of the lymphatic system, which are a major part of the body’s immune system. Gastric lymphomas occur when cells called lymphocytes, which are found in the stomach wall, become abnormal and grow uncontrollably.

Most lymphomas starting in the stomach are one of two subtypes of non-Hodgkin’s lymphoma:

• Mucosa-associated lymphoid tissue (MALT) lymphoma: A slow-growing type of lymphoma that affects the mucosa-associated lymphoid tissue. This tissue is not typically present in the gastric mucosa but can develop due to prolonged inflammation. This is why most gastric MALT lymphomas are associated with infection by the H. pylori bacteria.
• Diffuse large B-cell lymphoma (DLBCL): A fast-growing cancer that is sometimes called high-grade gastric lymphoma due to its aggressive nature. This type of gastric cancer might arise de novo — spontaneously and independently — in lymphocytes or transform from low-grade MALT lymphomas in the stomach wall.

Other rare cancers of the stomach

Other types of cancer that begin in the stomach but are extremely rare include:

• Squamous cell carcinomas: A type of gastric cancer that starts in squamous cells, which are thin, flat cells covering the stomach lining.
• Small cell carcinomas: An extremely rare and highly aggressive type of neuroendocrine tumor.
• Leiomyosarcomas: A cancer that arises from the smooth muscle cells of the stomach.