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: Fear from increased cancer risk is one of the most significant reasons for low acceptance of reliable contraceptive methods and low compliance. In this review, we included all cohort and case-control studies published in English up to December 2008. They were identified through a search of the literature using Pubmed and EMBASE. Data about breast cancer risk indicate a slightly increased risk among current users of oral contraceptives (OC), an effect which disappears 5-10 years after stopping. Combined OC have a significant protective effect on the risk of ovarian cancer, and the protection increases with duration of use (relative risk decreased by 20% for each 5 years of use). The significant risk reduction has been confirmed for BRCA 1 and 2 mutation carriers. The risk of endometrial cancer is reduced by about 50% in ever users, a benefit which is greater with increasing duration of use. An association has been found between increased risk of cervical cancer and long-term OC use. Current OC use has been associated with an excess risk of benign liver tumours and a modest increased risk of liver cancer. None of large prospective cohort studies with prolonged follow-up has observed an increased overall risk of cancer incidence or mortality among ever users of OC, indeed several have suggested important long-term benefits. Specifically, protective effect of OC can be used as chemoprevention in young women who are BRCA mutation carriers. Women wishing to use combined OC can be reassured that their decision is unlikely to place them at higher risk of developing cancer.Human Reproduction Update 02/1990; 16(6):631-50. · 9.23 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;
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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 1(3):139-147.