Colon cancer Health Article

Signs and tests

With proper screening, colon cancer can be detected before symptoms develop, when it is most curable.

Your doctor will perform a physical exam and press on your belly area. The physical exam rarely shows any problems, although the doctor may feel a mass in the abdomen. A rectal exam may reveal a mass in patients with rectal cancer, but not colon cancer.

A fecal occult blood test (FOBT) may detect small amounts of blood in the stool, which could suggest colon cancer. However, this test is often negative in patients with colon cancer. For this reason, a FOBT must be done along with colonoscopy or sigmoidoscopy. It is also important to note that a positive FOBT doesn't necessarily mean you have cancer.

Imaging tests to diagnose colorectal cancer include:

• Colonoscopy
• Sigmoidoscopy

Note: Only colonoscopy can see the entire colon.

Blood tests that may be done include:

• Complete blood count (CBC) to check for anemia
• Liver function tests

If your doctor learns that you do have colorectal cancer, more tests will be done to see if the cancer has spread. This is called staging. CT or MRI scans of the abdomen, pelvic area, chest, or brain may be used to stage the cancer. Sometimes, PET scans are also used.

Stages of colon cancer are:

• Stage 0: Very early cancer on the innermost layer of the intestine
• Stage I: Cancer is in the inner layers of the colon
• Stage II: Cancer has spread through the muscle wall of the colon
• Stage III: Cancer has spread to the lymph nodes
• Stage IV: Cancer has spread to other organs

Blood tests to detect tumor markers, including carcinoembryonic antigen (CEA) and CA 19-9, may help your physician follow you after treatment.

Treatment

Treatment depends partly on the stage of the cancer. In general, treatments may include:

• Chemotherapy to kill cancer cells
• Surgery (most often a colectomy) to remove cancer cells
• Radiation therapy to destroy cancerous tissue

Stage 0 colon cancer may be treated by removing the cancer cells, often during a colonoscopy. For stages I, II, and III cancer, more extensive surgery is needed to remove the part of the colon that is cancerous. (See: Colon resection)

There is some debate as to whether patients with stage II colon cancer should receive chemotherapy after surgery. You should discuss this with your oncologist.

Almost all patients with stage III colon cancer should receive chemotherapy after surgery for approximately 6 - 8 months. The chemotherapy drug 5-fluorouracil has been shown to increase the chance of a cure in certain patients.

Chemotherapy is also used to treat patients with stage IV colon cancer to improve symptoms and prolong survival.

• Irinotecan, oxaliplatin, capecitabine, and 5-fluorouracil are the three most commonly used drugs.
• Monoclonal antibodies, including cetuximab (Erbitux), panitumumab (Vectibix), and bevacizumab (Avastin) have been used alone or in combination with chemotherapy.

You may receive just one type, or a combination of the drugs.

For patients with stage IV disease that has spread to the liver, various treatments directed specifically at the liver can be used. This may include:

• Burning the cancer (ablation)
• Cutting out the cancer
• Delivering chemotherapy or radiation directly into the liver
• Freezing the cancer (cryotherapy)

Although radiation therapy is occasionally used in patients with colon cancer, it is usually used in combination with chemotherapy for patients with stage III rectal cancer.