Women on birth control may be at a slightly higher risk for breast cancer.
The study, published in Cancer Research, reveals that certain types of birth control pills may cause women to have an increased risk of breast cancer.
There are two different types of oral contraceptives. One is called a combined oral contraceptive, which contains estrogen and progesterone. The second type of oral contraceptive is called the minipill, which only contains progestin.
According to the National Cancer Institute, estrogen and progesterone have been found to influence cancer development, and since the combined pill contains man-made versions of both of these hormones, scientists are trying to see if there is a link between contraceptives and cancer.
Elisabeth Beaber, a staff scientist in the Public Health Sciences Division of Fred Hutchinson Cancer Research Center in Seattle, and her team found that recent use of oral contraceptives is associated with increased breast cancer risk. They used electronic pharmacy records to gather information about oral contraceptive use.
"Our results suggest that use of contemporary oral contraceptives [birth control pills] in the past year is associated to increased breast cancer risk relative to never or former oral contraceptive use, and that this risk may vary by oral contraceptive formulation," she said.
They found that pills with high-dose estrogen increased risk by 2.7 times while those that had a moderate estrogen dose increased risk by 1.6 times. Birth control pills with low to no estrogen did not increase risk for breast cancer. Pills with ethynodiol diacetate increased rates by 2.6 times and triphasic dosing with an average of 0.75 mg of norethindrone increased rates by 3.1 times, according to the study.
They concluded that there was a 50 percent increase in risk for breast cancer, but since less than 1 percent of women get breast cancer before age 40, the number would still be under 50 percent, as per the American Cancer Society.
"Our results require confirmation and should be interpreted cautiously," Beaber warned. "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 increased risk associated with recent oral contraceptive use declines after stopping oral contraceptives."
Beaber also said that the low-estrogen dose pill is the pill that is being increasingly prescribed by physicians. Women who are wondering what kind of formulation they are currently taking can check the packing information of specific doses and hormones in the pill.
