Use of Oral Contraceptives as a Potential Risk Factor for Breast Cancer: A Systematic Review and Meta-Analysis of Case-Control Studies Up to 2010

Abstract

Despite numerous studies evaluating the risk of breast cancer among oral contraception users, the effect of oral contraceptive on developing breast cancer remains inconclusive. Therefore, we conducted a systematic review of literature with meta-analysis in order to quantitative estimate this association. The bibliographic database MEDLINE and EMBASE, and reference lists of identified articles were searched, with no language restrictions, from the start of publication to August 2010. We performed a reanalysis and overall estimate of 79 case-control studies conducted between 1960–2010, including a total of 72,030 incidents, histologically confirmed cases of breast cancer and 123,650 population/hospital controls. A decrease was observed in cancer risk in OC users before age 25 years (0.91, 0.83–1.00). However, the use of OCs before the first full-term pregnancy had a significant increased risk of breast cancer (OR, 1.14, 1.01–1.28, p = 0.04), as did OC use longer than 5 years (1.09, 1.01–1.18, p = 0.02). Pooled crude odds ratios of breast cancer in ever-users of oral contraceptives was 1.01 [95% confidence interval (CI), 0.95–1.07], compared with never-users. There was no significant increase in risk among premenopausal women (1.06, 0.92–1.22), postmenopausal women (0.99, 0.89–1.10), or nulliparous women (1.02, 0.82–1.26). Oral contraceptives do not appear to increase the risk of breast cancer among users. However, OC use before a first full-term pregnancy or using them longer than 5 years can modify the development of the breast cancer.

Oral Contraceptive Use and Breast Cancer Risk Assessment: A Systematic Review and Meta-Analysis of Case-Control Studies, 2009–2020

“…Here, IRR (incidence rate ratio) = 1.04, 95% CI: 0.91 to 1.17 [ 70 ]. Our previous meta-analysis covering the period 1960–2010 [ 16 ] estimated 79 case-control studies conducted between 1960–2010, including a total of 72,030 incidents, histologically confirmed cases of BrCa and 123,650 population/hospital controls. A decrease was observed in cancer risk in OC users before age 25 years (0.91, 0.83–1.00).…”

“…Pooled crude odds ratios of BrCa in ever-users of OC was 1.01 [95% confidence interval (CI), 0.95–1.07], compared with never-users. There was no significant increase in risk among premenopausal women (1.06, 0.92–1.22), postmenopausal women (0.99, 0.89–1.10), or nulliparous women (1.02, 0.82–1.26) [ 16 ].…”

“…Our first meta-analysis on the effects of OC on BrCa risk covered the period 1960–2010 [ 16 ]. The meta-analysis included studies that examined the mixture of pills from four generations: the first-generation progestin included norethindrone, lynestrenol, ethynodiol diacetate, and norethisterone; the second-generation included levonorgestrel, and norgestrel, introduced in the 1990s; the third-generation included desogestrel, gestodene, and norgestodene introduced in the 1990s; and the last approved fourth-generation ethinyloestradiol/drospirone and estradiol valerate/dienogest.…”

Adherence to Oral Contraception in Young Women: Beliefs, Locus of Control, and Psychological Reactance

“…For gynecological problems, such as endometriosis and dysmenorrhea, it is recommended to consider whether there is a need for contraceptive medication, along with contraindications to hormonal therapy, and potential adverse effects [ 51 ]. Previous research indicated that knowledge of the risk factors of the medication is usually greater than of the beneficial effects, such as a reduced likelihood of contracting gynecological cancers, or other hormonal alterations [ 52 , 53 ]. In general, concerns about the consequences were the main factor involved in OCP definitive default.…”

Oral Contraceptive Use and Breast Cancer Risk According to Molecular Subtypes Status: A Systematic Review and Meta-Analysis of Case-Control Studies

“…The relationship between oral contraceptive (OC) taking and the risk of breast cancer has also been extensively researched. Findings suggest that OC use is associated with a moderately increased breast cancer risk in the general population [32][33][34][35].…”