Colon cancer can affect any part of the colon from the appendix to the beginning of the rectum. The last 15 cm of the bowel is the rectum. Colon cancer can be picked up incidentally e.g. the national bowel screening program. Some patients develop symptoms of cancer. The main symptoms of colon cancer are a change in bowel habit and or blood in the stool. Blood can be dark indicating that the blood source is on the right side of the colon. Bright red bleeding implies the source is in the left colon or rectum.
Bright red bleeding does not imply that there is a cancer. It must be taken in context with the other symptoms. The passage of red blood can occur from a cancer or from a haemorrhoid or a fissure. It is critically important that patients seek advice from their GP if they have rectal bleeding.
Other symptoms of cancer include weight loss, loss of appetite, fatigue, and a low blood count.
A colonoscopy can identify a colon cancer and a biopsy usually confirms the diagnosis. A biopsy is extremely important as many types of tumours can occur, and treatment must be directed appropriately. Once the diagnosis is confirmed, a CT scan is performed of the chest, abdomen and pelvis. This establishes if the tumour has spread beyond the colon. A blood test is taken to measure CEA (carcinoembryonic antigen). This is produced by certain tumours and can be measured after treatment to establish if the tumour has returned..
If a colon cancer is diagnosed the treatment is surgical removal. This is performed laparoscopically (keyhole surgery) but in certain cases it may need to be performed using an open, traditional operation.
Some patients receive chemotherapy first depending on the extent of their disease.
Following surgery, the patient has CT scans 6 monthly for 2 years and then annually for 3 further years. A colonoscopy is performed at 1 year. A CEA level is measured for 5 years Patient are followed for 5 years. While cancer can return after 5 years, this is unusual.