Original ResearchGynecologyLifetime cancer risk and combined oral contraceptives: the Royal College of General Practitioners’ Oral Contraception Study
Section snippets
Materials and Methods
Between May 1968 and July 1969, 1400 general practitioners (GPs) throughout the United Kingdom recruited approximately 23,000 women who were using oral contraceptives and 23,000 women who had never used this method of contraception.5 All women were married or co-habiting; most were white, and their mean age at recruitment was 29 years. Information collected at recruitment included previous use of oral contraception, smoking habits, social class (based on partner’s occupation according to the
Results
The dataset contained 4661 ever users with at least 1 cancer during 884,895 woman-years of observation and 2341 never users with at least 1 cancer during 388,505 woman-years of observation, which was an 81% increase in cancers and an 18% increase in periods of observation since our previous cancer analysis.8 Approximately one-tenth of never users who experienced cancer (246 women; 10.5%) and a similar proportion of ever users (458 women; 9.8%) had >1 type of cancer. The mean age of women at
Comment
Our results suggest that users of oral contraceptives are protected from colorectal, endometrial, and ovarian cancer for many years after stopping, perhaps for >35 years for colorectal and ovarian cancer. An increased breast and cervical cancer risk that is seen in current and recent users appears to be lost within approximately 5 years of stopping oral contraception, with no evidence of either cancer recurring at increased risk in ever users with time. An increased risk of lung cancer was seen
Acknowledgments
We thank many general practitioners who contributed data, the University of Aberdeen Data Management Team for database support, and Dr Gordon Prescott for assistance with the time since last use analyses.
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2022, The Lancet Regional Health - EuropeCitation Excerpt :The reason for this discrepancy may be explained by several factors. Firstly, many high quality studies have not identified any increased relative risk,10–13 and those that have, present small estimates with confidence intervals close to one.1–9 Secondly, the prescription of HC for contraception in Sweden is almost exclusively performed by nurse-midwives who are only allowed to prescribe combined HC to women who are not obese or smoking (if the woman is aged 35 years or more).
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Supported by the Royal College of General Practitioners, Medical Research Council, Imperial Cancer Research Fund, British Heart Foundation, Schering AG, Schering Health Care Ltd, Wyeth Ayerst International, Ortho Cilag and, Searle. None of these funders have contributed to the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review or approval of the manuscript.
The authors report no conflict of interest.
Cite this article as: Iversen L, Sivasubramaniam S, Lee AJ, et al. Lifetime cancer risk and combined oral contraceptives: the Royal College of General Practitioners’ Oral Contraception Study. Am J Obstet Gynecol 2017;216:580.e1-9.