The Pill and Breast Cancer Risk: More Food for Thought
Oct. 10, 2000 -- Using the birth control pill may not be a good idea for some women with a strong family history of breast cancer.
A new study in this week's Journal of the American Medical Association finds that these women may have up to an 11 times higher risk of breast cancer if they have ever taken the pill. But experts caution that the study involved mainly women who took the pill prior to 1975, when it contained much higher levels of the hormones estrogen and progestin than today's lower-dose pill.
Unfortunately, women with a strong family history of breast cancer also may be at increased risk of ovarian cancer, and studies have shown that the pill may help reduce that risk. In light of that, researchers now must ponder whether the new findings mean that women at highest risk of breast cancer should avoid taking the pill even if it means living with a higher risk of ovarian cancer.
But one of the study's authors tells WebMD that women at high risk who are taking or considering taking today's pill should not be concerned because their study and others have shown nothing to indicate that today's pill is as risky as the older version. Of women in the study who took the pill marketed after 1975, only two developed breast cancer.
"The risk from the early formulations [of the pill] appears to be real, and these women should be getting regular mammograms, if they are not already doing so," says co-author Thomas A. Sellers, PhD. "We're continuing to monitor our study population, but based on the results to date, there is no suggestion at all [that the newer lower-dose pill poses the same risk]," says Sellers of the Mayo Clinic in Rochester, Minn.
Compared with sisters and daughters of women with breast cancer who never took the pill, those with a similar history who did were more than three times as likely to develop breast cancer. The more family members with breast cancer, the greater the increase in risk associated with taking the pill. For instance, women with at least three blood relatives diagnosed with breast cancer had about a four-and-a-half times greater risk of breast cancer if they took the pill, and women with five or more blood relatives had an 11 times higher risk, compared with similar women who did not take the pill.
The study involved multiple generations from more than 400 families with members diagnosed with breast cancer between 1944 and 1952. The follow-up data to track additional breast cancer cases was done between 1991 and 1996.
Doctors say the study is important, but urge caution in interpreting the results.
"The breast cancer risk associated with [the pill] is bad news for women with a family history of breast cancer, particularly for those at very high risk," writes Wylie Burke, MD, in an editorial accompanying the study.