BACKGROUND AND PURPOSE:

• Older studies using older hormonal contraceptive formulations protect against ovarian cancer
• Limited data on newer formulations
• Iverson et al. (BMJ, 2018) assessed whether contemporary combined hormonal contraceptives are associated with overall and specific types of ovarian cancer

METHODS:

• Prospective, nationwide cohort study (1995-2014)
• Participants
  • Women age 15-45 years
  • Follow-up until whichever came first: First diagnosis of ovarian cancer death, emigration, age 50 years, or end of follow-up (December 31, 2014)
• Women’s exposure to contraceptives were categorized as
  • Never users (reference): No record of being dispensed hormonal contraception
  • Current users
  • Recent users: ≤1 year after stopping use
  • Former users: >1 year after stopping use
• Contraceptives were categorized by
  • Progestogen type in combined preparations
  • All progestogen-only products (including non-oral preparations)
• Separate analyses examined women followed up to their first contraception type switch and those with full contraceptive histories
• Primary outcome
  • Relative risk (RR) of ovarian cancer

RESULTS:

• 1,879,227 women were included
• During 21.4 million person years, 1,249 incident ovarian cancers occurred
  • Among ever users of hormonal contraception, 478 ovarian cancers were recorded over 13,344,531 person years
  • Never users had 771 ovarian cancers during 8,150,250 person years
• Compared with never users, ovarian cancer risk was reduced among those who had used hormonal contraceptives
  • Current or recent use: RR 0.58 (95% CI, 0.49 to 0.68)
  • Former use: RR 0.77 (95% CI, 0.66 to 0.91)
• Relative risks among current or recent users decreased with increasing duration (P<0.001)
  • ≤1 year use: RR 0.82 (95% CI, 0.59 to 1.12)
  • >10 years’ use: RR 0.26 (95% CI, 0.16 to 0.43)
• Little evidence of major differences based on
  • Tumor type
  • Progestogen content of combined OCPs
• Progestogen-only products did not alter ovarian cancer risk

CONCLUSION:

• Contemporary combined hormonal contraceptives, like previous formulations, are associated with a reduction in ovarian cancer risk
• No effect seen in progesterone-only contraceptives
• Duration of use increased the protective effect
• The authors state

It has been suggested that recent downward trends in ovarian cancer mortality rates in North America and Europe can be partly attributed to the use of combined oral contraceptives. We found a population prevented fraction of 21% with use of hormonal contraception, which supports the notion that these ovarian cancer mortality benefits are likely to continue.

Learn More – Primary Sources:

Association between contemporary hormonal contraception and ovarian cancer in women of reproductive age in Denmark: prospective, nationwide cohort study

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