What are the symptoms of colon cancer?
Colon cancer affects the stomach and bowels. Common symptoms include diarrhea or constipation, blood in the stool, vomiting, bloating, cramps, and unexplained weight loss.
How do doctors diagnose colon cancer?
Even before a patient shows symptoms of colon cancer, his or her doctor can screen for the disease using one of several tests:
• Fecal Occult Blood Test (FOBT) - Colon cancer can sometimes cause tiny dots of blood, too small for the eye to see, in the feces. The FOBT test uses a chemical to check the patient's stool sample for these traces of blood.
• Flexible-Sigmoidoscopy - Using a thin flexible tube called a simoidoscope, the doctor looks inside the patient's colon for growths called polyps.
• Double Contrast Barium Enema (DCBA) - A silvery-white metallic substance called barium is inserted into the patient's colon through the rectum. The barium outlines the patient's colon on an x-ray screen.
• Colonoscopy - Using a thin instrument called a colonoscope, the doctor looks inside the patient's colon. During the procedure, the doctor removes pieces of tissue (called a biopsy) to test them for cancer. If the doctor finds any polyps, he or she can also remove them. A newer method, called virtual colonoscopy, looks at the colon without going into the body, with an MRI or CT scan.
• DNA-Based stool test - This test examines DNA taken from a patient's stool sample to look for genetic defects associated with colon cancer.
How is colon cancer treated?
Colon cancer is very treatable. In fact, about 90 percent of patients survive the disease after treatment. First, doctors stage the disease to see how far it has progressed. If the cancer has not spread to other tissues of the body, it can be treated with chemicals (chemotherapy) or radiation (powerful x-rays) to kill all rapidly dividing cells in the body, including cancer cells or surgery to remove the polyps and/or cancerous part of the colon
Interesting facts about colon cancer
People who have FAP can develop hundreds and even thousands of polyps, whereas people with HNPCC develop relatively few.
The progression from a benign to a malignant cancer typically requires multiple mutations that allow cells to acquire new and abnormal characteristics, such as an increased growth rate, inability to adhere or stick to neighboring cells, and propensity to migrate to other places in the body. At least seven mutations are required to produce a malignant colon tumor.
Inherited cancers often provide clues about the genes mutated in noninherited (sporadic) cancers. For example, mutations in the APC gene are found not only in FAP tumors but in 85% of all sporadic colon tumors as well