University of Copenhagen, Denmark
Title: Newer oral contraceptives protect against ovarian cancer in young women
Øjvind Lidegaard is a Clinical Professor with expertise in Obstetrics & Gynaecology in University of Copenhagen, Denmark.
Material: Women 15-49 years during the period 1995-2014 were eligible. They were excluded if they immigrated after 1995, had previous cancer, venous thrombosis or were treated for infertility before entry. Final study population included 1,879,227 women.
Methods: Relative risk (RR) of ovarian cancer among users of any contemporary hormonal contraceptives was calculated using Poisson regression. Duration, time since last use and tumour histology were examined and the population prevented fraction calculated.
Results: During 21.4 million person-years, 1,249 incident ovarian cancers occurred. Compared to never users, reduced risks occurred with current or recent use; RR 0.58 (95% CI 0.49-0.68) and former use of any hormonal contraception RR 0.77 (0.66-0.91). RRs among current or recent users decreased with increasing duration; 0.82 (0.59-1.12) with Ë‚1-year use to 0.26 (0.16-0.43) with ≥10 years use. Similar results were achieved among women followed until first switch in contraceptive type. There was little evidence of major differences in risk estimates by tumour type or progestogen content of combined oral contraceptives. Progestogen-only products were not associated with ovarian cancer risk. Hormonal contraception prevented an estimated 21% of ovarian cancers in this population.
Conclusion: Contemporary combined hormonal contraceptives reduce ovarian cancer risk in young women, an effect related to duration of use, and which diminishes after stopping. Our data suggest no protective effect from progestogen-only products.