The colon and rectum are two adjacent parts of the large intestine, and cancer of these tissues is collectively called colorectal cancer. This type of cancer is the second leading cause of cancer death, according to the Centers for Disease Control and Prevention (CDC). The state of colorectal cancer advancement is often categorized by stages. The stage is based on physical exam, imaging tests and surgery results. The stage of cancer growth aids the doctor in determining the method and extent of treatment.
Stage 0
Stage 0 colorectal cancer is at the earliest stage of growth. Merck manuals, an online medical library, reports that this stage of colorectal cancer means that the location of the cancer cells is restricted to the inner lining of the colon and rectum. The 5-year survival rate of people with this stage of rectal cancer is 98 percent, meaning that 98 percent of patients diagnosed with this stage 0 colorectal cancer live at least 5 years.
Stage I
In stage I colorectal cancer, the cancer has grown through the inner lining of the colon or rectum and invaded the muscle wall, according to the American Cancer Society. Though it has invaded the muscle, it has not invaded into the outer layer of the colon, or spread elsewhere in the body. The prognosis of stage I colorectal cancer is still quite good, with a 5-year survival rate of 90 percent.
Stage II
The American Cancer Society states that stage II colorectal cancer is characterized by the invasion of the cancer through the inner and muscle layers of the colon or rectum, and into or through the outer wall. The cancer may even have become attached to nearby organs or tissues, but is not found elsewhere in the body. Merck Manuals adds that the 5-year survival rate of people with stage II colorectal cancer is quite variable, between 55 and 85 percent.
Stage III
Stage III colorectal cancer includes a wide range of cancer advancement. The cancer cells may have grown into or through the first layer, into or through the muscle layer, or into or through the outer layer of the colon or rectum. What distinguishes stage III colorectal cancer from earlier stages, according to the National Cancer Society, is that cancer cells are detectable in one or more lymph nodes, meaning the cancer has spread significantly outside the colon or rectum. The 5-year survival rate for stage III colorectal cancer, reported by Merck Manuals, is 20 to 55 percent.
Stage IV
Stage IV colorectal cancer is the most advanced stage of cancer growth. In this stage, according to Merck Manuals, the cancer cells have spread to distant organs and tissues in the body, whether or not they are found in the lymph nodes or have grown through the wall of the colon or rectum. Cancer may be found in the liver, the lungs, or in the ovaries of women. This stage of colorectal cancer has a very poor prognosis, with only 1 percent of patients surviving longer than 5 years.
