Many women take birth control pills (oral contraceptives). Studies show that current or recent use of birth control pills slightly increases the risk of breast cancer [155-157].
A large analysis that combined the results of many studies found that while women were taking birth control pills (and shortly thereafter), they had a 10 to 30 percent higher risk of breast cancer than women who had never used birth control pills [158]. Once women stopped taking the pill, their risk began to decrease and returned to normal in about 10 years. In most of the studies, the women were taking older, higher-dose forms of the pill.
One area still under study is how today's lower-dose pills affect breast cancer risk. One large case-control study found no link between birth control pills and breast cancer [159]. However, the findings from this single study are not compelling enough to change the conclusions based on the data as a whole. Although taking the pill slightly increases risk, most women on the pill are at low risk of breast cancer in general because they are fairly young and premenopausal. So even with a slight increase in risk, they are still unlikely to get breast cancer while they are on the pill.
Some types of birth control pills lower the number of periods a woman has during a year. Others contain progestin only and no estrogen (often called “mini-pills”). At this time, there are too few data to comment on whether these pills affect breast cancer risk the same as other types of birth control pills.
Before making any decisions about birth control pills, you should weigh the pros and cons of using them. Though they have some risks, birth control pills also have some advantages. These benefits include preventing unwanted pregnancies and decreasing the risk of both uterine and ovarian cancers [160,161].
Depo Provera and the birth control patch
Like birth control pills, Depo Provera (an injected contraceptive) and the birth control patch contain hormones. Depo Provera contains progestin alone, while the birth control patch contains both estrogen and progestin. At this time, data on the potential link between these products and breast cancer risk are limited [162,163]. The pooled results of two studies on Depo Provera showed no impact on breast cancer risk overall. A possible increase in risk was found among current users, but it is not clear whether this was due to increased screening among the women using Depo Provera [164]. You should talk to your health care provider about the pros and cons of these types of birth control before using them.
Updated 11/10/09
