Colorectal cancer starts as a polyp (a growth of tissue that can form on the lining of the colon or rectum). Some polyps are benign (not bad) while some are malignant. The malignant polyps can turn into cancer if not surgically removed. The earlier polyps are caught, the better. That is why colonoscopies are recommended for men and women over 50 and for those at increased risk of colorectal (affecting the colon and/or rectum) cancer. The following groups are at an increased risk of colorectal cancer: someone with a history of colorectal cancer, someone with a family history of colorectal cancer, a person with inflammatory bowel disease (Crohn’s disease or ulcerative colitis), and people with a known family history of hereditary colorectal cancer syndrome. Hereditary colorectal cancer syndrome includes familial adenomatous polyposis (FAP) or hereditary non-polyposis colon cancer (HNPCC).
TNM descriptions of Colorectal cancer
T describes how far the primary tumor has grown into and around the colon or rectum. T is usually expressed with numbers from 1 through 4. The higher the number means how much the tumor has grown into the colon or rectum and neighboring tissues.
N describes the number of lymph nodes near the colon or rectum. N is usually expressed with numbers from 0 to 3. N0 means the cancer has not spread to lymph nodes. N1-N3 indicates that the cancer has spread to lymph nodes and gives the number of lymph nodes with cancer.
M describes whether or not the cancer has metastasized (spread) to other body parts. M is expressed in numbers 0 and 1. M0 means the cancer has not spread and M1 means cancer has spread to other body parts.
Staging of Colorectal Cancer
There are 4 stages of colon cancer and a brief description of each is listed below.
Stage I (1): Cancer has begun to grow through the thin muscles in the colon but has not made it to the lymph nodes or other body parts.
Stage II (2): The cancer has grown into the wall of the colon or even grown through it but has not spread to any tissues, organs, or lymph nodes yet.
Stage III (3): The cancer has grown into the outer layers of the colon or have grown through the wall of the colon. It might have affected the lymph nodes and attached itself to nearby organs or tissues.
Stage IV (4): The cancer has spread to at least one distant organ. The most commonly affected organs include the liver, the lungs, and the peritoneal cavity (lining of the abdominal cavity).