Risk of breast cancer associated with short-term use of oral contraceptives.
ABSTRACT To estimate breast cancer risk associated with short-term (<6 months) oral contraceptive use, and explore variation in estimates by use characteristics and medical, menstrual, and reproductive history.
We analyzed data from the Women's Contraceptive and Reproductive Experiences Study. Case subjects were white women and black women, 35-64 years old, diagnosed with invasive breast cancer in July 1994-April 1998. Control subjects identified by random-digit dialing were matched to case subjects by age, race, and study site. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).
Overall, short-term oral contraceptive use was not associated with breast cancer risk (OR = 1.0; 95% CI = 0.8-1.1). However, significant interaction between short-term use and menopausal status led to an observed increased breast cancer risk in pre-menopausal women (OR = 1.3; 95% CI = 1.0-1.7) and a reduced risk in post-menopausal women (OR = 0.8; 95% CI = 0.6-1.0) associated with short-term use. The association was more pronounced in women with non-contraceptive reasons for use and underlying risk factors for breast cancer.
These associations may result from underlying characteristics of users or unmeasured factors influencing duration of use and breast cancer risk.
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ABSTRACT: Estrogen and progestin in oral contraceptives may be carcinogenic to the breast, and their use has been associated with a modest increase in the risk of breast cancer in the general female population. Women who carry deleterious mutations in breast cancer susceptibility genes, BRCA1 and BRCA2, have a significantly higher risk of breast and ovarian cancer. The literature on the role of oral contraceptives in carriers is sparse and the results are inconclusive. Findings from some case-control studies and the International BRCA1/2 Carrier Cohort Study suggest that oral contraceptive use may be associated with an increased risk of breast cancer in BRCA1 and BRCA2 carriers. Understanding the potential effects of oral contraceptive use among carriers has important implications for preventive strategies and clinical management. Both the possible protective effect for ovarian cancer risk and the increased potential risk of breast cancer must be considered.Current Breast Cancer Reports 09/2009; 1(3):139-147.
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ABSTRACT: Oral contraceptives (OC) 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 OC 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 OCs for contraception or ovarian cancer prevention; includes comparison group with no OC use; study reports quantitative associations between OC 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 performed by estimating pooled odds ratios with 95% confidence intervals. 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 OCs. Risk of cervical cancer was increased with duration of OC 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 OC use. Compared with never use, ever use of OCs 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 OCs may contribute to a substantial number of cases.Cancer Epidemiology Biomarkers & Prevention 09/2013; · 4.56 Impact Factor
Chapter: Exogenous Hormones[Show abstract] [Hide abstract]
ABSTRACT: Women worldwide have been prescribed medications containing female steroid sex hormones for the past several decades. These medications primarily containing various derivatives of estrogen and/or progesterone have been used for two main purposes, as menopausal hormone therapy (HT) and as contraceptives [primarily in the form of oral contraceptives (OCs)]. Given the central role of hormones in the etiology of breast cancer and the widespread use of these preparations, numerous studies have evaluated the relationship between both HT and various hormonal contraceptives and breast cancer risk. These relationships have been and continue to be of considerable interest to epidemiologists, physicians, and the general population. A summary of this large body of work is provided below including assessments of the impact different types of hormones have on different types of breast cancer.11/2009: pages 89-117;