What Is Stomach Cancer?

Stomach cancer, also known as gastric cancer, is a tumor that starts in the stomach. A tumor is a mass of cells with the cells growing and replicating uncontrollably. Generally speaking, stomach cancers can occur in any region of the stomach, with the different types of this cancer often characterized by its starting region. Some of the more common types of stomach cancer include adenocarcinomas, gastrointestinal stromal tumors, neuroendocrine tumors, and lymphomas.

• Adenocarcinomas: Account for 95% of cancers that occur in the stomach. This cancer develops from mucoid cells, cells that line the stomach, and the main cell type found in gastric glands. Adenocarcinomas tend to be either the intestinal type, meaning it begins in the intestine, or the diffuse type, meaning it affects many regions of the stomach as opposed to sticking in one area.

• Gastrointestinal stromal tumors: This is an uncommon type of stomach cancer. Gastrointestinal stromal tumors are a class of soft tissue sarcoma forming in neurons lining the stomach. While they can occur in any region of the gastrointestinal tract, they mainly form in the stomach.

• Neuroendocrine tumors (AKA carcinoid tumors): These tumors form in neuroendocrine cells, which have some properties like neurons and other properties like hormone-producing, endocrine cells. These types of tumors tend to grow slowly and are often relegated to the point of origin.

• Lymphomas: Lymphoma is a type of cancer in immune cells. Occasionally, the body will send immune cells to the stomach when fighting an illness. If these cells become cancerous, lymphoma can begin in the stomach.

The exact causes of stomach cancer are unknown; however, it is believed that most stomach cancers begin when the stomach lining is adversely affected. Non-cancerous stomach conditions that affect the stomach lining, like sores and infections, often precede stomach cancers. Additionally, unhealthy activities such as drinking and smoking have been linked to stomach cancers. Stomach cancer is especially likely to form when the stomach's inner lining is damaged to the extent that the cells in the lining develop an alteration in their DNA. These DNA mutations can cause the uncontrollable growth and division characteristic of cancerous cells.