Surgery is the most effective treatment for colorectal cancer. Even when all visible cancer has been removed, it is possible for cancer cells to be present in other areas of the body. These cancer deposits, when very small, are undetectable at the time of surgery, but they can begin to grow at a later time. The chance of recurrence depends on the characteristics of the original cancer and the effectiveness of chemotherapy, if needed, or other follow up treatment. Patients with recurrent cancers – if diagnosed early – may benefit, or be cured, by further surgery or other treatment.
Another good reason for postoperative follow up is to look for new colon or rectal polyps. Approximately one in five patients who has had colon cancer will develop a new polyp at a later time in life. It is important to detect and remove these polyps before they become cancerous.
Most recurrent cancers are detected within the first two years after surgery. Therefore, follow up is most frequent during this period of time. After five years, nearly all cancers that are going to recur will have done so. Follow up after five years is primarily to detect new polyps, and can, therefore, be less frequent but advisable for life.
Your doctor will examine you approximately every two or three months for the first two years, and discuss your progress. A CEA blood test can be done, as a method of trying to detect recurrence of cancer. Because this test is not totally reliable, other follow up examinations may be advised. These examinations may include flexible sigmoidoscopy (an examination of the rectum and lower colon with a flexible, lighted instrument), colonoscopy (examination of the entire colon with a long flexible instrument), chest x-rays, and sometimes CT scans or ultrasound tests.
Close relatives of patients with colon and rectal cancer (parents, brothers, sisters, children) are at increased risk for the disease. Because of this, periodic examination of the lining of the colon, using a colonoscope to detect small polyps, is advised. If polyps are promptly detected and removed, cancers cannot develop. Other factors which increase the risk of developing polyps or cancer include cancer occurring at an early age, and a personal history of breast or female genital cancer.