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Ovarian Cancer Chemoprevention

Learn about the steps that people at high risk for cancer can take to manage their risk and protect their health.

Oral contraceptives

Oral contraceptives are medications used by women for birth control; these medications have other important benefits and downsides. 

Impact on risk for ovarian cancer

Studies of women in the general population show that using birth control pills lowers the risk for ovarian cancer, but whether the medications provide the same protection for BRCA mutation carriers is unclear. A 2004 study involving 451 BRCA carriers who took oral contraceptives found that compared to women who did not use contraceptives, ovarian cancer risk decreased depending on the length of time the contraceptives were used:

  • Women who used oral contraceptives for at least 1 year had about a 15% reduced risk. 
  • Women who used oral contraceptives for 6 or more years had a 38% reduced risk. 

Other studies have had varied results, likely because findings may differ depending upon on the participants enrolled or the research design, studies on the same topic do not always have the same result.

Two analyses, one from 2013 and one from 2014, of published data from multiple studies found that oral contraceptive use was associated with a reduced risk of ovarian cancer in both of BRCA1 and BRCA2 mutation carriers.

Impact on risk for breast cancer

Using oral contraceptives greatly reduces the risk of pregnancy and may also decrease the chance of developing ovarian cancer, but also comes with a downside. All women who use these medications, whether or not they have BRCA mutations, may be at increased risk for breast cancer. A 2014 study of more than 2,000 women showed that among women with BRCA1 mutations:3

  • those who began using oral contraceptives before age 20 had a 45% increased risk of breast cancer compared to BRCA1 carriers who never used oral contraceptives. 
  • those who took oral contraceptives between ages 20 and 25 were at slightly increased risk for developing breast cancer before age 40. The risk was greater for women who used birth control pills for longer periods of time. 

These data support an earlier study that showed women with BRCA1 mutations who first used oral contraceptives before 1975, before age 30, or who used them for 5 or more years had an increased risk of early-onset breast cancer compared to BRCA1 carriers who never used the medications. (This study found no increased risk for breast cancer in women who carried a BRCA2 mutation.) A different study found no increased risk for breast cancer with use of more modern low-dose oral contraceptives. 

What does this mean for women at increased risk for cancer due to mutations in BRCA or other genes?

Because these studies were strictly observational, the findings were limited.

The study authors’ conclusions are noteworthy, but do not prove that taking oral contraceptives actually decreases ovarian cancer risk or increases breast cancer risk. More research is needed to understand contraceptive use and cancer risk in BRCA carriers.

Members of our advisory board agree that BRCA mutation carriers under the age of 25 must balance the risk of breast cancer with the risk of unintended pregnancy.  

Oral contraceptives may not be appropriate for all women with BRCA mutations who want to reduce their risk for ovarian cancer. Birth control pills can have side effects, including a slightly increased risk for blood clots. Anyone considering the use of oral contraceptives to lower their cancer risk should discuss the benefits, risks and limitations with their health care team and with experts in managing high-risk women.

Updated 12/29/16

 

 

 

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