Diagnosis & staging
These are tests that may be used to diagnose this type of cancer.
- General physical examination, including a digital rectal examination
- Routine lab and blood tests
- Testing of stool sample (feces) for occult (hidden) blood. (also, see Screening above)
- Barium enema X-ray. A special liquid is inserted into the colon by enema, and then x-rays are taken
- Sigmoidoscopy – doctors can examine the lowest 50 cm (20 inches) of the colon with a thin, lighted tube. They can also use this scope to grab tiny bits of suspicious looking tissue to put under the microscope
- Colonoscopy - doctors can examine both the upper and lower colon with a thin, lighted tube. They can also use this scope to grab tiny bits of suspicious looking tissue to put under the microscope
- Biopsy of colon or rectal tissue. A doctor removes a small portion of the colon or rectum to examine under a microscope. This is the most accurate test of all, but because it involves cutting the body, the other less invasive tests are usually done first.
- CT scan of abdomen and pelvis
- Ultrasound of abdomen
For more information on tests used to diagnose cancer, see our Recommended Websites, Diagnostic Tests
Types and Stages
- Most cases of bowel and rectal cancers are adenocarcinomas
- Sometimes a lymphoma or melanoma, sarcoma or squamous cell carcinoma may be found
- Cancer of the small intestine (not the colon or rectum) is different, as is anus cancer.
Staging describes the extent of a cancer. The TNM
classification system is used as the standard around the world. In general a lower number in each category means a better prognosis. The stage of the cancer is used to plan the treatment.
T describes the site and size of the main tumour (primary)
N describes involvement of lymph nodes
M relates to whether the cancer has spread (presence or absence of distant metastases)
Cancer is only in the bowel wall, not penetrating the muscle in the wall. The cure rate exceeds 90%
Lesions (an area of abnormal tissue) which penetrates muscle into the surrounding fat. The cure rate is about 70%
Regional lymph node involvement is demonstrated. Likelihood of cure is about 50%, depending on the number of lymph nodes involved
Patient has metastatic disease (the cancer has moved to other areas) or the tumour has grown and spread into other organs. The cancer is often incurable at this point, although there are treatments that can relieve symptoms, improve the quality of life and significantly extend life.