According to the results of a study published in the Journal of Clinical Oncology, use of oral contraceptives may increase breast cancer risk among women with a BRCA1 or BRCA2 mutation.
Inherited mutations in two genes-BRCA1 and BRCA2-have been found to greatly increase the lifetime risk of developing breast and ovarian cancer. Alterations in these genes can be passed down through either the mother’s or the father’s side of the family.
Among women with a BRCA1 or BRCA2 mutation, an important goal of research is to identify treatments, screening tools, and behavioral changes that can reduce the risk of developing cancer or improve early detection of cancer.
Although use of oral contraceptives has been linked with a decreased risk of ovarian cancer, some studies have suggested that it may also be linked with a small increase in breast cancer risk. Relatively few studies, however, have focused specifically on women with a BRCA1 or BRCA2 mutation.
To explore the relationship between oral contraceptive use and risk of breast cancer in women with a BRCA1 or BRCA2 mutation, an international group of researchers conducted a study among close to 1,600 female BRCA1/2 carriers. Seventy-three percent of the study participants had used oral contraceptives.
- Compared to women who had never used oral contraceptives, risk of breast cancer was 47% higher in women who had ever used oral contraceptives.
- Risk of breast cancer increased with longer duration of oral contraceptive use, particularly use prior to the first full-term pregnancy. Compared to women who had never used oral contraceptives, risk of breast cancer was 85% higher among women who had used oral contraceptives for at least nine years before first full-term pregnancy.
- The link between oral contraceptive use and increased breast cancer risk was observed among both BRCA1 and BRCA2 carriers.
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These results suggest that oral contraceptive use-particularly long-term use before first full-term pregnancy-may increase the risk of breast cancer in women with a BRCA1 or BRCA2 mutation. The researchers caution that these results are not conclusive, however, and that advice about oral contraceptive use should consider potential benefits as well as potential risks.
Reference: Brohet RM, Goldgar DE, Easton DF et al. Oral contraceptives and breast cancer risk in the International BRCA1/2 Carrier Cohort Study: A report from EMBRACE, GENEPSO, GEO-HEBON, and the IBCCS Collaborating Group. Journal of Clinical Oncology [early online publication]. July 16, 2007.
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