Stage IV Colon Cancer Prognosis

Colon cancer includes all cancers that originate within the colon. Often, colon cancer is related to rectal cancer, since the cancer is located within both the colon and rectum. This type of cancer is called colorectal cancer.
The majority of colon cancers (around 95%) begin with adenomas. An adenoma is a polyp that begins to grow in the colon's lining. Colon cancer typically grows slowly, spreading from the polyp to the colon or rectum's center. From there, it may progress into nearby lymph nodes or other organs. Like the majority of cancers, colon cancer has four stages (although Stage II has an A and B stage, and Stage III has an A, B and C stage). Colon cancer is considered to be Stage IV when it is metastatic (has spread to other parts of the body distinct from the colon and/or nearby lymph nodes and/or intestinal organs).

Staging of Colon Cancer

• Colon cancer, like the vast majority of cancers, is staged under a standard system called the AJCC Staging Sytem or the TNM staging system. The AJCC system was created by the American Joint Committee on Cancer and is called the TNM system because the T, N and M factors are the three factors used in staging the cancer.
  The T number is determined by a doctor who evaluates both the size and growth of the primary cancer. In liver cancer, the T number is diagnosed based on how many layers of the colon the tumor has penetrated. The layers include the innermost lining, (the mucosa) the thin muscle layer next to the mucosa (the muscularis mucosa), the fibers and tissue above the mucosa (the muscularis mucosa), the contracting muscle layer that helps move the contents through the intestine (the muscularis propi) and finally the outermost layers (the subserosa and serosa).
  The N number refers to lymph node involvement (whether the cancer has spread to nearby lymph nodes). The M number refers to whether the cancer has metastasized to other parts of the body distinct from the colon/rectum and general digestive system.

Stage IV Cancer

• Stage IV colorectal cancer refers to a cancer with any T number, any N number, and an M number of M1. This means that the level of layers of the colon and the lymph node involvement is not important in diagnosing Stage IV Cancer. A diagnosis of Stage IV cancer is always given when the cancer spreads from the primary site (the colon) to other sites on the body.

Common Sites of Metastases

• Colon cancer often metastasizes to the lungs, abdominal cavity lining (the peritoneum) or ovaries. The Memorial Sloan-Kettering Cancer Center estimates that approximately half of patients diagnosed with colon cancer experience liver metastases during the course of the disease.

Prognosis

• Cancer survival rates are determined by looking at the 5-year survival rates of patients diagnosed with a specific type of cancer. According to data garnered from databases at the National Cancer Institute, which looked at the survival rates of approximately 120,000 people diagnosed with colon cancer from 1991 to 2000, the 5-year survival rate for those diagnosed with Stage IV colon cancer is 8 percent. However, a study from the University of Texas MD Anderson Cancer Center suggests that, as of 2009, new treatments, including treatment for livery metastases, have increased these survival rates to 30 percent.

Treatment

• Surgery is the most common treatment for metastatic colon cancer. The surgery removes the cancer at the primary site (the colon) and at the site of metastases. Surgery (including cyrosurgery, a freezing of a part of the liver) can remove metastases from both the liver and lungs.