Colorectal Cancer Follow-up

For several years after treatment, it is important to have regular follow-up examinations to determine if any active cancer cells have returned. Physical and rectal exams by a physician, regular colonoscopy, and blood tests are important to help tell if the cancer has come back. Blood markers like CEA are present in some patients with active colon cancer, so a rise in these blood values is used as an early warning sign that the cancer has returned. However, some people without cancer also have CEA in their blood, so it cannot be used as a specific test for cancer.

Imaging with PET/CT is also critical in order to look for the return of the cancer. Other imaging tests might not detect the cancer, which could result in a delay of further treatment. In many patients with colorectal cancer, a mass may develop in the pelvis. The mass can be seen on a CT scan, but CT cannot determine if it is the result of surgical or radiation scarring or if it is a recurrent cancer that must be treated. If the mass is cancerous, it will demonstrate increased uptake of the radioactive glucose on the PET/CT scan. If, however, the mass is because of scarring caused by the radiation treatments, no glucose uptake will be seen in the abnormality.

PET/CT can be used to image tumor response to therapy and to detect recurrence in treated lesions. After surgery and other treatments, PET/CT is extremely important for monitoring to see if the cancer cells have returned and if treatment should be restarted.

PET/CT can be used to image colorectal cancer response to therapy and to detect recurrence in treated lesions.