Smoking plus gene variant raises breast cancer risk

By Amy Norton

NEW YORK (Reuters Health) - Women with a particular gene mutation linked to breast cancer may further raise their risk of the disease if they smoke, a study has found.

The gene in question is known as the ataxia-telangiectasia, or A-T, gene. At least 1 percent of the population carries a mutation in the gene, and women who carry mutated A-T have a higher-than-average risk of developing breast cancer.

But until now it had not been known whether smoking increases this risk even more. Studies on smoking and breast cancer in the population as a whole have generally found little or no evidence that the habit contributes to the disease.

These latest findings, however, should give women yet another reason not to smoke, according to lead researcher Dr. Michael Swift, of the Disease Insight Research Foundation in Ardsley, New York.

While the study focused only on women with an A-T mutation, most women who carry such a mutation do not know it, Swift told Reuters Health.

So it's wise -- for a whole range of health reasons -- for all female smokers to give up the habit.

Most people do not know whether they have an A-T mutation because the defect causes no symptoms when a person carries only one copy of the mutated gene. In the uncommon case where a child inherits two copies of a mutated A-T gene -- one copy from each parent -- it causes ataxia- telangiectasia, a disorder that attacks the nervous system.

So while parents of children with ataxia-telangiectasia know they are carriers, most carriers remain unaware.