Several birth control pills may increase risk of breast cancer: Study​

A new study found that women who recently used certain birth control pills that contain a high level of estrogen were at an increased risk for developing breast cancer, compared to women who did not use such contraceptives.

The researchers analyze oral contraceptive records and prescriptions of 1,102 women diagnosed with breast cancer between the ages of 20 and 49 and compared it with a group of similar unaffected women.

The researchers at the Fred Hutchinson Cancer Research Center in Seattle, Wash., found recent oral contraceptive use increased breast cancer risk by 50%.

"Our results suggest that use of contemporary oral contraceptives in the past year is associated with an increased breast cancer risk relative to never or former oral contraceptive use, and that this risk may vary by oral contraceptive formulation," researcher Elisabeth Beaber said in a press release.

She warned the results need to be confirmed with more research and the study "should be interpreted cautiously."

"There are numerous oral contraceptive formulations," explained Beaber, a staff scientist at the Fred Hutchinson Cancer Research Center in Seattle. "Some of these formulations increase breast cancer risk while other formulations do not raise risk."

Birth control pills containing high-dose estrogen increased breast cancer risk 2.7-fold, and those containing moderate-dose estrogen increased the risk 1.6-fold, the study found. 

The study was published in the journal Cancer Research.