A new study has found that birth control pills and injectable contraceptives may raise breast cancer risks and lower risks for ovarian cancer. The study reviewed women’s use of both injectable and oral birth control methods.
While users of these types of contraceptives were at a significantly lowered risks for ovarian cancer, they were at a significantly increased relative risk of developing invasive breast cancer, said ABC News. The study was based on a review of black women in South Africa. Risks decreased as time passed after the contraceptives were ceased.
Injectable contraceptives are a common form of birth control Birth by black women in South Africa, the authors noted; in the U.S., birth control pills are more typically used by women, said ABC News. Combined injectables provide monthly hormones to prevent pregnancy, which is similar to how oral contraceptives work. Hormones are some of the most popularly prescribed and taken medications in the world with about 9% of women aged 15-49 taking oral contraceptives and 4% using injectable contraceptives or implants in 2007, according to a 2009 United Nations report, said ABC News.
Globally, more than 210 million women currently use either hormonal contraceptive pills or injectable contraceptives. Contraceptive pills usually contain manmade versions of the female sex hormones estrogen and progesterone; most injectable hormonal contraceptives contain only manmade progesterone preparations.
Hormonal contraceptives, which prevent pregnancy by disrupting the cyclical changes in estrogen and progesterone levels that prepare the body for pregnancy, have revolutionized birth control since they first became available in the early 1960s.
However, it is now known that taking the pill also influences women’s risk of developing cancers of the female reproductive system. Current and recent users have an increased risk of developing breast and cervical cancer compared to those that have never used them, although this increased risk quickly disappears when women stop taking the pill. By contrast, women who have used the pill have a reduced risk of developing ovarian cancer and cancer of the womb compared to never users that increases with the duration of pill use and persists for many years after use ceases. These effects on reproductive system cancers are thought to occur because these cancers depend on naturally occurring sex hormones for their development and growth.
For the study, data was self-reported by 5,702 participants who were newly diagnosed with invasive breast, cervical, ovarian, or endometrial cancers, said ABC News; 1,492 women served as controls and were diagnosed with other cancers such as colon, rectal, and non-Hodgkin lymphoma, which are not affected by contraceptives. Of the participants, 26% used injectable hormones and 20 used pills.
After adjustments were made for so-called “confounding factors” such as age, education, smoking, and the number of sexual partners, the researchers found that women were 1.7 times likelier to develop breast cancer and 1.4 times likelier to develop cervical cancer, versus women who never took the contraceptives, ABC News said. About half of the women with breast cancer, 26% of the women with ovarian cancer, and 17% of the women with endometrial cancer had used the contraceptives.
The study authors concluded that, “Nevertheless, we found that women who had used oral and/or injectable contraceptives for a duration of less than 5 years had significantly reduced risks of both ovarian and endometrial cancer compared with women who had never used hormonal contraceptives.”
Oral contraceptives are continually being linked to a number of adverse events. It is best when deciding which method to use that you properly research all of the possible side effects and choose which is you best option. Keeping in mind that abstinence may ultimately be the best option!
The study appears in PLoS Medicine.