Certain mutations in the BRCA1 and BRCA2 genes can increase a woman's chances of developing breast cancer or ovarian cancer dramatically. But that doesn't mean all women should line up for laboratory testing to see if they have those risky versions of the genes, members of a government panel said Monday.

Unless she has a family history that makes it likely she has the harmful mutations, a woman will be unlikely to benefit from genetic counseling and genetic tests, the U.S. Preventive Services Task Force wrote, in an updated draft recommendation on screening for BRCA-related cancer risk.

The group recommended that primary care doctors handle initial screening interviews to assess BRCA-related cancer risk. Women whose family histories suggest they have an elevated chance of having the harmful versions of the genes should then be referred to genetic counseling for further evaluation and discussion of the risks and benefits of testing. Only after such genetic counseling should DNA testing to look at BRCA variations be warranted, they said.

In its report, the task force outlined the risks faced by women who have the dangerous mutations. In the general population, 12.8% of women are expected to develop breast cancer and 2.8% will die from it; 1.4% are expected to get ovarian cancer and 1% to die from it. But the chances climb steeply for women with the harmful BRCA variants, with the likelihood of getting breast cancer by age 70 increased to 34% to 70%. Bad versions of BRCA1 increase ovarian cancer risk by the age of 70 to 41% to 46%; BRCA2 mutations, to 17% to 23%.

With those kinds of odds, it's understandable that woman who might be likely to have the mutations -- those with a strong family history of breast or ovarian cancers, and some ethnic groups such as Ashkenazi Jews -- would want to find out. Early discovery of the added risk can let women get more frequent screening or take over preventive measures. But for the more than 90% of women in the population whose family histories do not suggest they have the harmful versions of the genes, the panel wrote, the uncertainty introduced by the sometimes-inconclusive results of genetic testing can cause more harm than good -- including unnecessary stress and unneeded tests and treatment.