combined oral contraceptives and breast cancer risk

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There is evidence (1,2) that women who currently use or have stopped using combined oral contraceptive pills have a slightly increased risk of breast cancer (odds ratio 1.24 for current users and 1.16 for women who stopped using the pill one to four years before). In this study (1) there was no increase in risk seen after 10 years of stopping the pill.

The evidence was derived from using results of 54 case-control studies and pooling them to compare past exposure to oral contraceptive pills among women with and without a history of breast cancer.

A review concluded that (2) "..Any increased risk of breast cancer with COC use is likely to be small, but is in addition to background risk, which is particularly relevant to older women.."

Estimated cumulative numbers of breast cancers per 10,000 women diagnosed in 5 years of use and up to 10 years after stopping COCs, compared with numbers of breast cancers diagnosed in 10,000 women who had never used COC.

Age of COC use (years)Cancers found up to age (years)Cumulative number of breast cancers per 10,000 women diagnosed in 5 years of use and up to 10 years after stopping COCsCumulative number of breast cancers diagnosed in 10,000 women who had never used COCsCumulative excess per 10,000 women associated with COC use
Under 20 304.540.5
20-243517.5161.5
25-294048.7444.7
30-344511110011
35-395018116021
40-445526223032

Advice to women with family history of breast cancer (2):

  • women aged up to 35 years with a family history of breast cancer is in keeping with general health advice on the use of the oral contraceptive pill. Women aged over 35 years with a family history of breast cancer should be informed of an increased risk of breast cancer associated with taking the oral contraceptive pill, given that their absolute risk increases with age
  • provision of a combined hormonal contraceptive to women who are carriers of known gene mutations associated with breast cancer (e.g. BRCA1) requires expert clinical judgement and/or referral to a specialist contraceptive provider. Women with genetic mutations have a much higher baseline risk of breast cancer than women who do not have these mutations

Women should be advised that current use of CHC (combined hormonal contraception) is associated with a small increased risk of breast cancer which reduces with time after stopping CHC (3).

Reference:

  1. BMJ Editorial. Oral contraceptives and breast cancer. BMJ 1996; 313: 63-4
  2. MeReC Bulletin (2006); 17(2):1-9.
  3. FSRH (July 2019). Combined Hormonal Contraception

Last edited 03/2020 and last reviewed 04/2021

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