Breast cancer gene may increase other cancer risks

Carrying mutated gene raises risk for cancers Gallbladder and bile duct: 497 percent higher risk Prostate: 465 Pancreas: 351 Stomach: 259 Melanoma: 258

August 3, 1999
Web posted at: 5:24 p.m. EDT (2124 GMT)

WASHINGTON (CNN) -- The same genetic mutation that puts some people at increased risk of breast and ovarian cancer may also increase their odds of getting prostate, pancreatic and other cancers, according to a study released Tuesday.

People who carry the mutated BRCA2 gene have been known to face a higher risk of breast and ovarian cancer, although both diseases are still rare even among the gene's carriers.

Previous studies have suggested there may be a link between BRCA2 and other cancers, but the study released in the Journal of the National Cancer Institute is the first that confirms that people whose genes carry the mutation may face higher odds of getting prostate and pancreatic cancer, as well as mouth cancer, stomach cancer, skin cancer and gallbladder cancer.

Ashkenazi Jews and families from Iceland are frequent carriers of this gene.

The study, carried out by the Breast Cancer Linkage Consortium and the Cancer Research Campaign in Cambridge, England, looked at 3,728 people. Of those, 681 had breast or ovarian cancer, and 3,047 were known to be either carriers of the gene, first-degree relatives of known carriers, or first-degree relatives of breast or ovarian cancer patients.

The study calculated cancer risks for carriers of this mutation and compared them with cancer risks of non-carriers. Researchers found increases in risks for: pancreatic cancer (351 percent higher); gallbladder and bile-duct cancer (497 percent higher); stomach cancer (259 percent higher); malignant melanoma (258 percent higher); prostate cancer (465 percent higher); prostate cancer for men below age 65 (733 percent higher).

In women with BRCA2 who already had cancer in one breast, their cumulative risk of developing cancer in the other breast by age 70 was 52.3 percent, and the risk of developing ovarian cancer was 15.9 percent.

An oncologist who specializes in inherited breast cancers said the study was well designed and offers useful information for doctors. Dr. Claudine Isaacs of Georgetown University said such studies may increase interest in genetic testing, but, she cautioned, the cancers still occur only rarely, even among carriers of the mutation.

Many people do not undergo testing for disease-causing genes because they fear their insurers will drop them or increase their rates.

Isaacs said people who carry the mutation may want to consider being tested anyway. Those who do test positive for the gene can limit sun exposure to reduce their odds of getting skin cancer, and receive regular checkups from skin doctors to diagnose and treat it before it becomes deadly.

However, Isaacs said, there are no precautions one can take to reduce the risk of some of the other cancers.