Stomach Cancer Stages

Doctors use the term stage to describe how far cancer has grown and whether it has spread to other parts of the body. Knowing the stage of your cancer helps your care team plan the best treatment and gives some information about what to expect.

Stomach cancer is staged using the TNM system developed by the American Joint Committee on Cancer. TNM stands for Tumor, Nodes, and Metastasis. This system describes how deeply the tumor has grown into the stomach wall, whether cancer has spread to lymph nodes, and whether it has spread to distant organs. The final stage is assigned based on the TNM information after surgery in most cases, though clinical staging based on imaging and endoscopy is used before surgery to guide initial treatment decisions.

The TNM Staging System for Stomach Cancer

Stage 0: Carcinoma in situ

Cancer cells are found only in the innermost layer of the stomach lining, called the mucosa, and have not grown into deeper layers. This is the earliest possible stage of stomach cancer and is highly curable.

Stage I: Early cancer confined to the stomach wall

• Stage IA: The tumor has grown into the mucosa or the next layer called the submucosa. No lymph node spread.

• Stage IB: The tumor has grown into the muscular layer of the stomach wall, or into the submucosa with spread to one or two nearby lymph nodes.

Stage II: Cancer has grown deeper or spread to a limited number of lymph nodes

• Stage IIA: The tumor has grown into the muscle layer with limited lymph node spread, or into the outer layers of the stomach wall with no lymph node spread.

• Stage IIB: The tumor has grown through the stomach wall or has spread to more lymph nodes, but has not spread beyond the stomach and its immediate surroundings.

Stage III: More extensive local spread

• Stage IIIA: The tumor has grown deeply into or through the stomach wall and has spread to several nearby lymph nodes.

• Stage IIIB: The tumor has spread to nearby structures or to a larger number of lymph nodes.

• Stage IIIC: The cancer has spread to many lymph nodes or has involved nearby structures along with lymph node spread.

Stage IV: Distant spread

The cancer has spread to distant organs such as the liver, lungs, or peritoneum, or to lymph nodes in distant parts of the body. Stage IV stomach cancer is not curable with standard treatments, though systemic therapy can control the cancer and extend life.

Tumor grade

The grade of the tumor describes how different the cancer cells look from normal cells and how quickly they are likely to grow and spread.

• Well-differentiated, or Grade 1. The cells look mostly like normal stomach cells and tend to grow more slowly.

• Moderately differentiated, or Grade 2. The cells have features between Grade 1 and Grade 3.

• Poorly differentiated or undifferentiated, or Grades 3 and 4. The cells look very different from normal cells and tend to grow and spread more quickly. Diffuse-type adenocarcinomas are typically poorly differentiated.

Lauren classification

Stomach adenocarcinomas are also commonly classified using the Lauren system, which divides them into two main types based on how the cancer cells are arranged:

• Intestinal type. The cancer cells form gland-like structures similar to those seen in intestinal tissue. Intestinal-type stomach cancer is more closely linked to H. pylori, atrophic gastritis, and environmental risk factors, and it tends to affect older patients.

• Diffuse type. The cancer cells spread individually through the stomach wall rather than forming distinct glands. Diffuse-type stomach cancer tends to grow more widely through the stomach, is more likely to be hereditary in some cases, and often has a worse prognosis. It is more common in younger patients.

Recurrent stomach cancer

Stomach cancer can return after initial treatment. When it does, doctors assess the location and extent of the recurrence before recommending next steps. Recurrence may be:

• Local recurrence. Cancer returns at or near the site where the original cancer was treated.

• Regional recurrence. Cancer returns in nearby lymph nodes or structures in the abdomen.

• Distant recurrence. Cancer returns in distant organs such as the liver, lungs, bones, or peritoneum.