A new study found that women who use birth control pills are 50 percent at risk of developing breast cancer compared to those who use other methods.
About 62 million women in the United States between ages 15 and 44 use birth control pills. 64 percent currently use hormonal methods-- the pill, vaginal ring, patch, implant and IUD, while 37 percent rely on sterilization. These two are the most commonly used methods since 1982.
Known side effects reported by women taking birth control pills include irregular menstrual bleeding, nausea, headaches, mood changes and blood clots, but a recent study discovered a new and disturbing side effect, which increases the risk of breast cancer.
Study leader Elizabeth Beaber from the Public Health Sciences Division of Fred Hutchinson Cancer Research Center in Seattle, Wash., worked with her colleagues in reviewing the electronic pharmacy records of 23,504 women; five percent of the participants were diagnosed with breast cancer during the study period.
The team then looked at the different types of birth control pills used by those who developed breast cancer to determine which posed more risk.
"Birth control pills containing high-dose estrogen increased breast cancer risk 2.7-fold, and those containing moderate doses of estrogen increased the risk 1.6-fold. Pills containing ethynodiol diacetate increased the risk 2.6-fold, and triphasic combination pills containing an average of 0.75 milligrams of norethindrone increased the risk 3.1-fold," the authors wrote.
The study revealed that using birth control pills could increase one's risk of developing breast cancer by 50 percent, as opposed to those who were not taking pills. This conclusion is made after considering other factors, such as the drug name, dosage, and duration of medication.
"Our results suggest that the use of contemporary oral contraceptives [birth control pills] 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," Beaber said.
Researchers recommend birth control pills with low doses of estrogen, as they found that those are less likely to increase the risk of breast cancer. Other suggestions include switching to non-hormonal methods instead.
Further details of the study were published in the August 1st issue of Cancer Research.
