Oral contraceptive use and estrogen/progesterone receptor-negative breast cancer among African American women.

Slone Epidemiology Center at Boston University, 1010 Commonwealth Avenue, Boston, MA 02215, USA.
Cancer Epidemiology Biomarkers & Prevention (Impact Factor: 4.32). 08/2010; 19(8):2073-9. DOI: 10.1158/1055-9965.EPI-10-0428
Source: PubMed

ABSTRACT Oral contraceptive formulations have changed over time, making it relevant to assess the effect of more recent formulations on breast cancer risk. In addition, some studies have found stronger positive associations of oral contraceptive use with estrogen receptor-negative (ER(-)) than with ER-positive (ER(+)) breast cancer. We carried out the first assessment of the effect of oral contraceptive use on the incidence of breast cancer classified by receptor status among African American women, a group disproportionately affected by ER(-) cancer.
We followed 53,848 Black Women's Health Study participants from 1995 to 2007 through biennial health questionnaires, in which participants reported information about incident breast cancer, oral contraceptive use, and breast cancer risk factors. Pathology information was obtained on receptor status for 789 incident cases. Incidence rate ratios (IRR) with 95% confidence intervals (95% CI) were derived from Cox regression models with control for confounding factors.
Ever use of oral contraceptives was more strongly associated with ER(-)PR(-) breast cancer (279 cases; IRR, 1.65; 95% CI, 1.19-2.30) than with ER(+)PR(+) cancer (386 cases; IRR, 1.11; 95% CI, 0.86-1.42). The risk of ER(-)PR(-) breast cancer increased with increasing duration of use among recent users.
These results indicate that the oral contraceptive formulations used in recent decades increase breast cancer risk in African American women, with a greater effect for ER(-) than ER(+) cancer.
Mechanisms to explain the adverse influence of oral contraceptive use on ER(-) breast cancer need to be elucidated.

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    ABSTRACT: Previous studies of oral contraceptives and breast cancer indicate that recent use slightly increases risk, but most studies relied on self-reported use and did not examine contemporary oral contraceptive formulations. This nested case-control study was among female enrollees in a large U. S. integrated health care delivery system. Cases were 1,102 women ages 20 to 49 years diagnosed with invasive breast cancer from 1990 to 2009. Controls were randomly sampled from enrollment records (n = 21,952) and matched to cases on age, year, enrollment length, and medical chart availability. Detailed oral contraceptive use information was ascertained from electronic pharmacy records and analyzed using conditional logistic regression, ORs, and 95% confidence intervals (CI). Recent oral contraceptive use (within the prior year) was associated with an increased breast cancer risk (OR, 1.5; 95% CI, 1.3-1.9) relative to never or former OC use. The association was stronger for estrogen receptor-positive (ER+; OR, 1.7; 95% CI, 1.3-2.1) than estrogen receptor-negative (ER-) disease (OR, 1.2, 95% CI, 0.8-1.8), although not statistically significantly different (P = 0.15). Recent use of oral contraceptives involving high-dose estrogen (OR, 2.7; 95% CI, 1.1-6.2), ethynodiol diacetate (OR, 2.6; 95% CI, 1.4-4.7), or triphasic dosing with an average of 0.75 mg of norethindrone (OR, 3.1; 95% CI, 1.9-5.1; P-heterogeneity compared with using other oral contraceptives = 0.004) was associated with particularly elevated risks, whereas other types, including low-dose estrogen oral contraceptives, were not (OR, 1.0; 95% CI, 0.6-1.7). Our results suggest that recent use of contemporary oral contraceptives is associated with an increased breast cancer risk, which may vary by formulation. If confirmed, consideration of the breast cancer risk associated with different oral contraceptive types could impact discussions weighing recognized health benefits and potential risks. (C)2014 AACR.
    Cancer Research 08/2014; 74(15):4078-89. DOI:10.1158/0008-5472.CAN-13-3400 · 9.28 Impact Factor
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    ABSTRACT: Recent oral contraceptive (OC) use has been consistently associated with increased risk of breast cancer, but evidence on specific breast cancer subtypes is sparse. We investigated recency and duration of OC use in relation to molecular subtypes of breast cancer in a pooled analysis of data from the African American Breast Cancer Epidemiology and Risk Consortium. The study included 1,848 women with estrogen receptor-positive (ER+) breast cancer, 1,043 with ER-negative (ER-) breast cancer (including 494 triple negative (TN) tumors, which do not have receptors for estrogen, progesterone, and human epidermal growth factor 2), and 10,044 controls. Multivariable polytomous logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for exposure categories relative to never use, controlling for potential confounding variables. OC use within the previous 5 years was associated with increased risk of ER+ (OR 1.46, 95% CI 1.18 to 1.81), ER- (OR 1.57, 95% CI 1.22 to 1.43), and TN (OR 1.78, 95% CI 1.25 to 2.53) breast cancer. The risk declined after cessation of use but was apparent for ER+ cancer for 15 to 19 years after cessation and for ER- breast cancer for an even longer interval after cessation. Long duration of use was also associated with increased risk of each subtype, particularly ER-. Our results suggest that OC use, particularly recent use of long duration, is associated with an increased risk of ER+, ER-, and TN breast cancer in African American women. Research into mechanisms that explain these findings, especially the association with ER- breast cancer, is needed.
    Breast Cancer Research 12/2015; 17(1). DOI:10.1186/s13058-015-0535-x · 5.33 Impact Factor
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    ABSTRACT: Background: Evidence suggests that recent oral contraceptive (OC) use is associated with a small increased breast cancer risk; yet risks associated with contemporary OC preparations and by molecular subtype are not well characterized. Methods: We conducted a population-based case-control study of invasive breast cancer among women ages 20-44 residing in the Seattle-Puget Sound area from 2004-2010 (985 cases and 882 controls). We collected information on contraceptive use and participant characteristics via an in-person interview. Multivariable-adjusted logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Results: Lifetime duration of OC use for ≥15 years was associated with an increased breast cancer risk (OR=1.5, 95% CI=1.1-2.2). Current OC use (within 1 year of reference date) for ≥5 years was associated with an increased risk (OR=1.6, 95% CI=1.1-2.5) and there were no statistically significant differences in risk by OC preparation. Risk magnitudes were generally greater among women ages 20-39, and for estrogen receptor negative (ER-) and triple-negative breast cancer (current use for ≥5 years among ages 20-39: ER- OR=3.5, 95% CI=1.3-9.0; triple-negative OR=3.7, 95% CI=1.2-11.8), though differences between groups were not statistically significant. Conclusions: Long-term use of contemporary OCs and current use for ≥5 years was associated with an increased breast cancer risk among women ages 20-44. Risk may be greater among younger women and for ER- and triple-negative breast cancer, but these findings require confirmation. Impact: Continued surveillance and pooled analyses of OC use and breast cancer risk by molecular subtype are needed as OC preparations evolve.
    Cancer Epidemiology Biomarkers & Prevention 03/2014; 23(5). DOI:10.1158/1055-9965.EPI-13-0944 · 4.32 Impact Factor

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