Thousands of women have been tested for BRCA1 and BRCA2, gene mutations linked to a very high risk of breast and ovarian cancer. Most women found to carry either mutation have chosen to have frequent monitoring. Some, however, have had their breasts, ovaries, or both removed in a desperate effort to prevent the often-deadly cancers. Turns out that these drastic measures work better than monitoring for both cancers, and removing the ovaries leads to longer lives than does screening for early detection, according to a study published Tuesday in the Journal of the American Medical Association.
[See the Best Cancer Hospitals Rankings.]
None of the 247 women in the study who had preventive mastectomies developed breast cancer during three years of follow-up, while 7 percent of the 1,372 women screened with frequent ultrasounds and mammograms were diagnosed with the disease. What's more, 3 percent of the 975 women screened for ovarian cancer developed the disease while none of the 442 women did who had their ovaries and fallopian tubes surgically removed. This procedure, called a salpingo-oophorectomy, also lowered the risk of developing breast cancer and of dying from breast or ovarian cancer. "This is the first study to show that this risk-reducing surgery can extend the life of women," says Virginia Kaklamani, an associate professor of medicine at Northwestern University, who wrote an editorial that accompanied the study.
Given the results of this study and earlier ones showing that the preventive surgeries drastically slash rates of ovarian and breast cancer, Kaklamani, an expert in breast cancer genetics, says that BRCA1 and BRCA2 carriers should strongly consider having their ovaries removed when they're no longer interested in childbearing—ideally by age 40, since cancers associated with these mutations often occur before menopause. Deciding whether to have a preventive mastectomy, she adds, is a bit tougher. While it reduces the risk of breast cancer, so far no studies have demonstrated that preventive mastectomy actually saves or lengthens lives. Still, it should be considered a viable option, having been shown to prevent a large percentage of breast cancers in gene carriers. (About 1 in every 500 women carries one of the mutations; the incidence is 10 times higher in Jewish women of Eastern European descent.)
[Genetic Tests Marketed to Consumers Can Be Dangerously Misleading]
The new research findings don't warrant genetic testing for every woman. Cancer experts generally recommend testing for those who have two or more close blood relatives (mother, daughter, sister, aunt, grandmother) who had breast cancer or ovarian cancer at any age, one or more close relatives who had either cancer before age 50, or a close male relative with breast cancer. Jewish women with Eastern European roots are also advised to get tested if any close family members have had breast or ovarian cancer. Make sure to count paternal relatives, since the mutations can be passed down through fathers as well as mothers.
"Doctors who see these family histories should be referring women to genetic counselors for testing," says Muin Khoury, a senior consultant in public health genomics at the National Cancer Institute. (Here's how to find a genetic counselor.) Steer clear of genetic tests offered on the Internet. These online testing companies, says Khoury, look for numerous gene variations to assess your risk of breast cancer and other diseases, but unlike the BRCA mutations, the variations haven't been well tested to determine whether they really are associated with an increased disease risk. That means you could falsely be labeled "high risk" for a particular disease, prompting action where none may be necessary. In fact, a recent review of these testing companies by the U.S. General Accounting Office concluded that the results they generated were "misleading and of little or no practical use." Above all, these tests should not be used to determine whether or not to have preventive surgeries to reduce cancer risks, says Khoury.
Aside from BRCA testing, several other genetic tests are useful for determining whether you have a high risk of developing certain cancers. As with BRCA, tests for these particular genetic cancers should be considered only in those with strong family histories.
- Melanoma. If this deadly skin cancer runs in your family, you should ask your doctor about getting tested for inherited melanoma. The test looks for mutations in genes called CDKN2A and CDK4. Those who test positive should visit a dermatologist every six months, says Kaklamani, for skin checks to detect moles and other growths before they turn cancerous. And they should take seriously the oft-repeated advice to cover up and use sunscreen.
- Colon cancer. You may be at increased risk if close relatives developed colon cancer before age 60 or had colon cancer as well as endometrial cancer. Tests screen for gene mutations that cause hereditary forms of colon cancer such as familial adenomatous polyposis and Lynch syndrome. Those who have these gene mutations can get a yearly colonoscopy to remove polyps before they become cancerous, says Kaklamani. Those with dozens or hundreds of polyps, though, may want to consider surgery to remove all or part of their colon, which has been shown to cut cancer risks.
- Thyroid cancer. Hereditary thyroid cancer is more deadly than traditional thyroid cancer. Genetic testing looks for mutations in the RET gene, and removing the gland—a thyroidectomy—may be the best way to prevent cancer. Taking thyroid hormone pills would then be necessary.
While more genetic tests for cancer will surely crop up in the next few years, inherited gene mutations account for a small portion of cancer cases; most cancers are caused by a combination of lifestyle and environmental factors and how they interact with your genes. A negative test for a cancer-causing gene can bring some relief, but it doesn't completely eliminate your risk of getting that cancer.
Reader Comments Read all comments (9)