Assessing the impact of contraceptive use on cancer risk among women of reproductive age – a systematic review

Abstract

Abstract Objectives: This review investigates the effects of modern contraceptive use such as birth control pills, injectables, long-acting reversible contraceptives (e.g., intrauterine devices, implants), and condoms on cancer risk. Methods: We searched the CINAHL, OVID Medline, EMBASE, Psycho INFO, Maternity & Infant Care, LILACS, clinical trial.gov, web of science, SCOPUS, and CENTRAL Database from inception until February 2022, with no geographical restrictions. We included studies with the following study designs: parallel or cluster randomized controlled trials, controlled clinical trials, controlled before and after studies, interrupted time series studies, cohort or longitudinal analyses, regression discontinuity designs, case-control studies. We only included studies that included a comparison group, using a control group with no contraceptive usage. As appropriate, studies were combined for meta-analysis when identical modern contraceptive tools, drugs, dosages, or regimens were used. We calculated relative risk or mean difference with a 95% confidence interval for each dichotomous or continuous outcome, respectively. Forest plots were produced for each comparison and outcome when two or more data points were identified. Main Results: Cohort studies suggest significant reductions in the risk of developing ovarian (RR 0.66 95% CI [0.62,0.70]), cervical (RR 0.54 [0.48, 0.62] and endometrial (RR 0.69 95% CI [0.64,0.74]) cancers among contraceptive users. No significant differences were reported between users and non-users who had breast or colorectal cancer. Conclusions: Contraceptives can protect women from ovarian and endometrial cancers. However, we found contraceptive use to be associated with an increased risk for cervical cancer regardless of contraceptive use duration. The findings necessitate additional research regarding the link between hormonal contraceptive use and cancer incidence. Providers should select contraceptive methods according to the situation of women with contraceptive intentions, taking age, physical status, mental status, family history, etc. into account to maximize benefits and minimize risks.