Stomach (Gastric) Cancer Overview
Stomach cancer is part of a group of cancers, called gastrointestinal cancers, that affect the gastrointestinal tract and other organs contained within the digestive system.
Stomach cancer, also called gastric cancer, is a disease in which malignant (cancerous) cells form in the lining of the stomach. The stomach is part of the digestive system, located in the upper abdomen between the esophagus and the small intestine. It makes stomach acid and enzymes that digest food. The stomach is made of five different layers. In most cases, stomach cancer begins in the mucosa, the deepest layer.
Almost all (90-95%) stomach cancers are adenocarcinomas of the stomach. These cancers develop from the cells that form in the innermost lining of the stomach, the mucosa. Other types of stomach cancers include:
- Carcinoid tumor – These tumors start in hormone-making cells of the stomach. Most of these tumors do not spread to other organs.
- Gastrointestinal stromal tumor (GIST) – Rare tumors such as these start in special cells in the wall of the gastrointestinal (GI) tract, also known as the digestive tract. Not all tumors are cancerous. Although GISTs can be found anywhere in the digestive tract, most are found in the stomach.
- Lymphoma – These are cancers of the immune system tissue that are sometimes found in the wall of the stomach. The type of lymphoma determines both the treatment and the prognosis (outlook).
After a stomach (gastric) cancer diagnosis has been made, your doctor will try to figure out if the cancer has spread, and if so, how far, through a process called staging. The stage of a cancer determines how serious the cancer is as well as what the best form of treatment will be.
The American Joint Committee on Cancer (AJCC) TNM system is the staging system most often used for stomach cancer. In regards to staging, TNM refers to:
- T: Tumor size and extent of tumors
- N: Lymph node involvement
- M: Presence or absence of distant metastasis (whether or not the cancer has spread to other areas of the body)
Stages of Stomach Cancer
Your cancer can be stage 1, 2, 3, or 4. The lower the number, the less the cancer has spread. A higher number, like stage 4, means a more serious cancer that has spread from where it started. Below are the details of each class:
- Stage 0 — Abnormal cells are present but have not spread to nearby tissue.
- Stage I, II, III — Cancer is present. The higher the number, the larger the cancer tumor and the more it has spread into nearby tissues.
- Stage IV — The cancer has spread to distant parts of the body.
When stomach cancer is found very early, there is a better chance of recovery. Stomach cancer is often in an advanced stage when it is diagnosed since it is slow growing with no distinguishable symptoms. Stomach cancer often goes undiagnosed for many years until it is in stage III or IV of the disease and has spread beyond the wall to nearby lymph nodes and organs such as the esophagus, liver, pancreas, and colon.
The main treatments for stomach (gastric) cancer are:
- Surgery – Surgery may be done to remove the cancer and part or all of the stomach and some nearby lymph nodes, depending on the type and stage of stomach cancer.
- Chemotherapy – Chemotherapy (chemo) may be given before surgery (neoadjuvant treatment) to shrink the tumor, after surgery (adjuvant treatment) to remove the cancer, or as the primary (main) treatment for stomach cancer that has metastasized (spread) to distant organs.
- Radiation Therapy – Radiation therapy may be used along with chemo before surgery to help shrink the tumor and/or after surgery to help kill any remaining cancer. It may also be used to slow the growth and ease the symptoms of advanced stomach cancer.
- Targeted Therapies – Targeted therapy drugs may work in some cases of stomach cancer when standard chemo drugs don’t.
- Immunotherapy – Immunotherapy medicines may be used to help the patient’s own immune system find and destroy stomach cancer cells.
Stomach cancer may make it harder for patients to eat and digest food. However, proper nutrition is essential to treatment and recovery. Registered dietitian and oncology nutritional services can help cancer patients going through stomach cancer treatment understand how to maintain nutrition during treatments in order to stay strong.
Some patients may receive nutrition through an IV (intravenous) until they are able to eat on their own. This will be discussed with the oncologist and dietitian to determine if this is needed and for how long.
Through our affiliation with US Oncology, our national research partner, clinical research trials are available to answer scientific questions and find new and better therapies for treating cancer. Much of the research around gastric cancers is looking at combining targeted agents with chemotherapy or with each other. Newer oral chemotherapy drugs available in other parts of the world, but not yet in the United States are also being studied. Clinical trials are also evaluating the effects of neoadjuvant or adjuvant chemoradiation therapy on surgical results and new ways of delivering chemo, including direct infusion into the abdomen.