Three organizations have guidelines about colon cancer testing in the U.S.:

• Preventive Services Task Force, or USPSTF (a panel of health experts from many different medical backgrounds)
• American Cancer Society (a panel of cancer experts)
• American College of Gastroenterology (a panel of experts in diseases of the colon and gastrointestinal system)

These groups have slightly different recommendations. Here's what I recommend to my patients, and to you.

Everyone should be tested for colon cancer beginning at age 50. The USPSTF says the evidence of a continued benefit from testing ends at age 75. Other organizations recommend testing after age 75.

There are different ways to test for colon cancer. The two recommended by all three organizations are colonoscopy and testing for blood in the stool.

Colonoscopy is the more accurate test. And if any precancerous growths (adenomas) are found during the test, they can be removed. However, colonoscopy has unpleasant aspects, including the process to clean out the bowel before the procedure and discomfort from the test itself. Also, colonoscopy can, rarely, lead to complications.

At age 49, you're close to the age when you should start being tested. Because you have a family history of colon cancer, you might be at an increased risk of getting colon cancer. In many cases, people with a family history of this disease start their testing earlier than age 50.

Some rare inherited genetic conditions put people at much higher risk of getting colon cancer. Anyone known to have such a condition, or to have a close relative with such a condition, should consult their doctor in early adulthood about whether they need testing.

Even if you are not in a family with one of these rare inherited conditions, you still may be at increased risk. If a first-degree relative (parent, sibling, child) developed colon cancer after age 60, you probably can wait until age 50 to be tested. If one or more first-degree relatives developed colon cancer before age 60, I recommend that my patients start testing after age 35 to 40, but not all doctors agree with that. If your relative with colon cancer is not a first-degree relative, you probably can wait until age 50 to begin testing.

You asked about the symptoms of colon cancer. The most important point is that, like many cancers, there often are no symptoms until the cancer has spread. That's why testing is so important. Any blood in your bowel movement is a warning sign, although blood is usually caused by non-cancerous conditions, like hemorrhoids. Other warnings signs include the development of new constipation, and unusual pain in your abdomen. But don't wait for warning signs to get tested.