Recent Use of Some Birth Control Pills Ups Breast Cancer Risk

Women using birth control pills, which contain high-dose estrogen, face an elevated risk of developing breast cancer, a new study reveals.

Birth control pills or oral contraceptives use synthetic hormones to prevent pregnancy. The new study found that women who recently used birth control pills - which have high levels of estrogen and a few other formulations - face a heightened risk of developing breast cancer - which is the second leading cause of death among women.

The study indicates that the use of contemporary oral contraceptives in the past one year or so is linked with an increased risk of breast cancer; the risk varies by oral contraceptive formulation.

"Our results require confirmation and should be interpreted cautiously," said Elisabeth F. Beaber, PhD, MPH, a staff scientist in the Public Health Sciences Division of Fred Hutchinson Cancer Research Center in Seattle, Washington. "Breast cancer is rare among young women and there are numerous established health benefits associated with oral contraceptive use that must be considered. In addition, prior studies suggest that the increased risk associated with recent oral contraceptive use declines after stopping oral contraceptives."

The current case control study included nearly 1,102 women diagnosed with breast cancer and 21,952 controls. The researchers found that the recent oral contraceptive use elevated the risk of breast cancer by almost 50 percent, when compared to women who never used the pills or were former users of the pills. The participants were at the Group Health Cooperative in the Seattle-Puget Sound area. They also received cancer diagnosis between 1990 and 2009.

The birth control pills that have high dose of estrogen elevated the risk of breast cancer 2.7-fold and the pills having moderate dose of estrogen increased the risk by 1.6-fold. The pills that had ethynodiol diacetate increased the risk by 2.6 fold and triphasic combination pills having an average of 0.75 milligrams of norethindrome raised the risk by 3.1-fold.

Those pills that did not have estrogen, did not increase the risk of breast cancer.

"About 24 percent, 78 percent, and less than 1 percent of study controls who were recent oral contraceptive users filled at least one prescription in the past year for low-, moderate-, and/or high-estrogen dose oral contraceptives, respectively," according to Beaber.

The study was documented in the journal Cancer Research.