DR. MARIANNE J. LEGATO: Deciding not to have this screening can be dangerous for both you and your mom, because colon cancer is not rare by any means. It’s the third leading cause of cancer deaths in women, but it’s almost always curable if detected early. Nonmalignant tumors (called polyps) are the precursors of colon cancer and may take about 10 to 15 years to become malignant. During a colonoscopy, your doctor can easily detect and remove any polyps before they become a threat. While a family history of colon cancer in a parent or sibling increases risk two to three times, it isn’t the only thing that affects vulnerability. Obesity and smoking are risk factors too. Studies have shown, however, that taking one milligram of folic acid each day, regular exercise, and a diet rich in fruits and vegetables and low in red meats and fat can help prevent the disease. Screening should begin at 40 for those with a family history and at 50 for everyone else. After the first screening, you should go every five to ten years (talk to your doctor). Many people who refuse a colonoscopy do so because of embarrassment or distaste for the preparation, which usually involves drinking several quarts of liquid and taking a laxative the day before the exam. The day of, you’ll be given a medicine to sedate you during the procedure. Then a colonoscope is inserted into the rectum, allowing your doctor to see the lining of your entire colon and remove any polyps. The entire exam usually takes about 30 minutes.

Marianne J. Legato, M.D., is the medial adviser to Ladies’ Home Journal and founder and director of the Partnership for Gender-Specific Medicine at Columbia University.