Some Oral Birth Control Pills Increase Breast Cancer RisksAug 4, 2014
A new study reveals that some oral contraceptives are associated with an elevated likelihood of developing breast cancer.
Research results were published in the August 1 issue of the journal, Cancer Research and involved research conducted by investigators from Seattle, Washington-based Group Health Research Institute, Group Health Cooperative; the Fred Hutchinson Cancer Research Center; and the University of Washington, according to the Los Angeles Women's Health Examiner.
The team discovered that prior research concerning the association between oral contraceptives and breast cancer uncovered a slight, increased risk; however, most of the research relied on women’s self-reported use and, also, did not review current birth control pill formulations. The new study looked at information on female enrollees in a large United States integrated healthcare delivery system, according to Los Angeles Women's Health Examiner. The research involved 1,102 women between the ages of 20 and 49 who were diagnosed with invasive breast cancer from 1990 through 2009. The 921,952 control patients were randomly selected from enrollment records. The women were then matched to breast cancer cases by age, year, enrollment length, and medical chart availability. Specific oral contraceptive use information was received from electronic pharmacy records and was subjected to statistical analysis.
The researchers also found that women who reported recent oral contraceptive use—with “recent” defined as being within the previous year—experienced an associated increased breast cancer risk that was defined as 1.5-fold compared to never or former oral contraceptive use. The risk was greater and increased to 1.7-fold for estrogen receptor–positive contraceptives and was slightly lower for estrogen receptor negative (1.2-fold), according to the Los Angeles Women's Health Examiner. The researchers also discovered that recent high-dose estrogen birth control use was associated with a 2.7-fold risk. With ethynodiol diacetate, the increased risk was 2.6-fold and, with triphasic dosing in which there was an average of 0.75 mg of norethindrone, the increased risk was 3.1-fold.
The researchers concluded that recent use of contemporary oral contraceptives is tied to increased risks for breast cancer, and these risks may vary by the medication’s formulation. The team also indicated that women who have a family history of breast cancer and/or who carry the BRCA1 or BRCA2 gene, the increased risk for developing breast cancer exists regardless of if an oral contraceptive is or is not taken. Taking an oral contraceptive may increase breast cancer risks, they added, according to the Los Angeles Women’s Health Examiner.
The authors also found that taking oral contraceptives was tied to a 50 percent increased risk for breast cancer in women who were similar to those who were studied in the research and who were between 20 and 49 years of age.