Colon Cancer

Are You A Candidate For Colon Cancer Testing?

If your family has a history of colorectal and related cancers, you may want to consider genetic testing for mutations in two genes strongly associated with a hereditary nonpolyposis colon cancer (HNPCC). The syndrome increases lifetime risk of colorectal cancer to 80 percent vs. a two percent population risk, but also boosts your risk of endometrial cancer (to 60 percent), ovarian cancer (to 12 percent) and gastric cancer (to 13 percent). Those with HNPCC also face a higher risk of cancers of the kidney and ureter, gallbladder, central nervous system and small bowel.

To determine whether testing might be appropriate for your family, a genetic counselor would look for incidence of these cancers in two or more family members at a young age (under 50), or incidence of two types of cancer in one family member at a young age. Testing is also an option if you have two first-degree relatives (parents, siblings or children) diagnosed with one of these cancers at any age.

Many aspects of the testing parallel BRCA testing. The ideal initial candidate is a person who has been diagnosed with cancer, and the initial test runs about $2,000 with subsequent tests for other family members costing about $300.

Preventive options for those who test positive include:

• Annual colonoscopies beginning in the early to mid-20s
• Annual screening for endometrial cancer using transvaginal ultrasound and/or endometrial aspirate beginning in the 20s
• Prophylactic surgery to remove the colon (rarely recommended), the uterus and/or the ovaries

Genetic counseling is vital at every step to help educate you to make the best choices for yourself and your family.

There are also tests available for mutations associated with a rarer colon cancer syndrome called familial adenomatous polyposis, which is typified by a very early age of onset (the teens) and appearance of many polyps.