Colon adenocarcinoma is a type of colon cancer. According to the National Cancer Institute, risk factors include a family history of colon or rectal cancer, an age of 50 or older, a personal history of cancer or finding polyps--non-cancerous growths in the colon. If an oncologist detects colon cancer, they will perform staging using various tests such as CT scans to determine how advanced the cancer has become.
Stage 0
According to the American Cancer Society, oncologists stage adenocarcinoma of the colon according the TNM classification. T stands for tumor and refers to the size of the primary lesion. N stands for nodes and refers to the number of lymph nodes--small nodules of the immune system that have become involved. Finally, M stands for metastases, and indicates whether the cancer has spread. Stage 0 is defined as Tis N0 M0. This means the tumor is "in situ" or has not spread beyond the innermost layer of the colon, has no lymph node involvement and no metastases.
Stage 1
Stage 1 colon cancer refers to the growth of the primary tumor according to the National Cancer Institute. It is either classified as a T1 N0 M0 or a T2 N0 M0. This means that no lymph nodes have become involved in the cancer and no metastasis has occurred. However, the tumor has grown larger than in stage 0. A T1 tumor has invaded past the innermost tissues of the colon. In T2 it has spread even deeper into the wall, says the American Cancer Society.
Stage 2
Stage 2 colon cancer is also divided into substages. In stage 2A, the cancer has spread beyond the middle tissues of the colon wall to the outermost layers, reports the American Cancer Society. In stage 2B, the cancer has grown completely through the wall of the colon but has not invaded nearby structures. Stage 2C is characterized if the cancer has spread beyond the colon wall to attach to or invade nearby organs and no lymph nodes or metastasis are found.
Stage 3
The third stage of colon cancer has positive lymph node involvement. In stage 3A, the primary tumor proves smaller, having not spread through the inner layers of the wall of the colon, but the lymph node have become involved. In stage 3B, the tumor has grown to the outermost layers of the wall and the numbers of lymph node involvement has increased. Stage 3C is characterized by lymph node involvement and a tumor that has grown through the wall of the colon, says the National Cancer Institute.
Stage 4
Stage 4 colon adenocarcinoma refers purely to the presence of metastases. It is divided into two sub-stages. Stage 4A is characterized by the presence of metastasis to one distant organ such as the lungs or liver. The primary tumor may be any size and there may be any number of lymph nodes involved, states the American Cancer Society. Stage 4B is the same, but with more than one organ involved by metastases.
