title: Oral contraceptive use and risk of breast, cervical, colorectal, and endometrial cancers: a systematic review.
abstract: Oral contraceptives may influence the risk of certain cancers. As part of the AHRQ Evidence Report, Oral Contraceptive Use for the Primary Prevention of Ovarian Cancer, we conducted a systematic review to estimate associations between oral contraceptive use and breast, cervical, colorectal, and endometrial cancer incidence. We searched PubMed, Embase, and Cochrane Database of Systematic Reviews. Study inclusion criteria were women taking oral contraceptives for contraception or ovarian cancer prevention; includes comparison group with no oral contraceptive use; study reports quantitative associations between oral contraceptive exposure and relevant cancers; controlled study or pooled patient-level meta-analyses; sample size for nonrandomized studies ≥100; peer-reviewed, English-language; published from January 1, 2000 forward. Random-effects meta-analyses were conducted by estimating pooled ORs with 95% confidence intervals (CIs). We included 44 breast, 12 cervical, 11 colorectal, and 9 endometrial cancers studies. Breast cancer incidence was slightly but significantly increased in users (OR, 1.08; CI, 1.00-1.17); results show a higher risk associated with more recent use of oral contraceptives. Risk of cervical cancer was increased with duration of oral contraceptive use in women with human papillomavirus infection; heterogeneity prevented meta-analysis. Colorectal cancer (OR, 0.86; CI, 0.79-0.95) and endometrial cancer incidences (OR, 0.57; CI, 0.43-0.77) were significantly reduced by oral contraceptive use. Compared with never use, ever use of oral contraceptives is significantly associated with decreases in colorectal and endometrial cancers and increases in breast cancers. Although elevated breast cancer risk was small, relatively high incidence of breast cancers means that oral contraceptives may contribute to a substantial number of cases.
authors.affiliation: Authors' Affiliations: Center for Health Services Research in Primary Care, Durham Veterans Affairs Medical Center; Duke Evidence-Based Practice Center, Duke Clinical Research Institute; Departments of Medicine, Community and Family Medicine, Obstetrics and Gynecology, and Biostatistics and Bioinformatics, Duke University School of Medicine; Duke Cancer Institute, Duke University Health System; Duke Clinical Research Institute, Durham; and Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Gierisch
authors.forename: Remy R
authors.initials: RR
authors.lastname: Coeytaux
authors.forename: Rachel Peragallo
authors.initials: RP
authors.lastname: Urrutia
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Havrilesky
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Moorman
authors.forename: William J
authors.initials: WJ
authors.lastname: Lowery
authors.forename: Michaela
authors.initials: M
authors.lastname: Dinan
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: McBroom
authors.forename: Vic
authors.initials: V
authors.lastname: Hasselblad
authors.forename: Gillian D
authors.initials: GD
authors.lastname: Sanders
authors.forename: Evan R
authors.initials: ER
authors.lastname: Myers
mesh_terms: D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D003276:Contraceptives, Oral / Q000008:administration & dosage* / Q000009:adverse effects; D016889:Endometrial Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D002583:Uterine Cervical Neoplasms / Q000139:chemically induced / Q000453:epidemiology*
chemical_list: D003276:Contraceptives, Oral