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High-Dose Estrogen Birth Control Pills May Increase Risk of Breast Cancer, Study Shows

New research shows that higher estrogen doses in some birth control pills may be linked to a higher risk for breast cancer.

In the study, women who took high-dose estrogen birth control pills were 50 percent more likely to develop breast cancer. Women using other formulations of the pill that contained low-dose estrogen were not found to be at an increased risk.

The study was led by researchers at the Fred Hutchinson Cancer Research Center in Seattle.

The results are based on data about recent oral contraceptive use, in those who were diagnosed with breast cancer and 22,000 healthy women who served as the comparison group. The women were all between the ages of 20 and 49. Research looked at the years 1990 through 2009.

The study was published Friday in the journal Cancer Research.

“There are numerous oral contraceptive formulations,” explained lead researcher Dr. Elisabeth Beaber, a staff scientist at the Fred Hutchinson Cancer Research Center, to U.S. News and World Report. “Some of these formulations increase breast cancer risk while other formulations do not raise risk.”

According to Beaber, estrogen pills containing 50 micrograms ethinyl estradiol or 80 micrograms mestranol were associated with nearly a three-fold higher risk of breast cancer. Pills with 0.75 milligrams of norethindrone were also linked to this very high risk category.

Birth control pills with a progestin, called ethynodiol diacetate, were linked to about a 2.6 times higher risk of breast cancer.

While 30 to 35 micrograms of ethinyl estradiol or 50 micrograms mestranol correlates with a 1.6 times higher risk.

But there are many options on the market containing a low dose of 20 micrograms of estrogen or less. This formulation doesn’t appear to increase the risk.

This is still not a definitive cause of breast cancer, as there are many other variables to consider, such as family history. Before considering a birth control method, a woman should always consult with her health care provider.

S.C. Rhyne is a blogger and novelist in New York City. Follow the author on Twitter @ReporterandGirl, and visit her website at

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