Oral Contraceptive, Breast Cancer Link Varies by Formulation
Friday, August 1, 2014 (Last Updated: 08/05/2014)
FRIDAY, Aug. 1, 2014 (HealthDay News) -- Recent use of oral contraceptives is associated with increased breast cancer risk, which varies by formulation, according to a study published in the Aug. 1 issue of Cancer Research.
Elisabeth F. Beaber, Ph.D., M.P.H., from the Group Health Cooperative in Seattle, and colleagues conducted a nested case-control study among females in a large U.S. health care delivery system. Data were examined for 1,102 patients, aged 20 to 49 years, diagnosed with invasive breast cancer from 1990 to 2009, and 21,952 matched controls randomly sampled from enrollment records.
The researchers found that, compared with never or former oral contraceptive use, recent use (within the prior year) correlated with increased breast cancer risk (odds ratio [OR], 1.5; 95 percent confidence interval [CI], 1.3 to 1.9). The risks were particularly elevated for recent use of contraceptives involving high-dose estrogen (OR, 2.7; 95 percent CI, 1.1 to 6.2), ethynodiol diacetate (OR, 2.6; 95 percent CI, 1.4 to 4.7), or triphasic dosing with an average of 0.75 mg of norethindrone (OR, 3.1; 95 percent CI, 1.9 to 5.1), but not for low-dose estrogen oral contraceptives (OR, 1.0; 95 percent CI, 0.6 to 1.7).
"If confirmed, consideration of the breast cancer risk associated with different oral contraceptive types could impact discussions weighing recognized health benefits and potential risks," the authors write.
Hematology & Oncology
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