Breastfeeding, tubal ligation, and oral contraceptives may lower the risk of ovarian cancer for some women with BRCA gene mutations, according to a comprehensive analysis.
The research team, from the University of Pennsylvania Basser Research Center for BRCA and the Abramson Cancer Center in Philadelphia, found that breastfeeding and tubal ligation are associated with reduced rates of ovarian cancer in BRCA1 mutation carriers, and the use of oral contraceptives is associated with a reduced risk of ovarian cancer in patients with BRCA1 or BRCA2 mutations. Their findings were published in the Journal of the National Cancer Institute (2014; doi:10.1093/jnci/dju091).
The meta-analysis of 44 existing peer-reviewed studies also helped better define factors that may increase risk among this population: Smoking, for instance, may raise the risk of breast cancer for patients with a BRCA2 mutation. Though the team cautions that more data are required before definitive conclusions about these variables can be made, the findings help to shed light on nonsurgical risk reduction options for women who may not be ready to undergo prophylactic removal of their ovaries to cut their cancer risk.
“Our analysis reveals that heredity is not destiny, and that working with their physicians and counselors, women with BRCA mutations can take proactive steps that may reduce their risk of being diagnosed with ovarian cancer,” said lead author Timothy R. Rebbeck, PhD, of Abramson Cancer Center. “The results of the analysis show that there is already sufficient information indicating how some variables might affect the risk of cancer for these patients.”
BRCA1 and BRCA2 are human genes that produce tumor-suppressing proteins. A woman’s risk of developing breast or ovarian cancer is notably increased if she inherits a harmful mutation in either the BRCA1 or BRCA2 gene from either parent. Fifty-five percent to 65% of women who inherit a harmful BRCA1 mutation and approximately 45% of women who inherit a harmful BRCA2 mutation will develop breast cancer by age 70 years, compared with approximately 12% of women in the general population. Rates of ovarian cancer and several other types of cancer are also increased by harmful BRCA mutations.
Though the study’s findings point to a helpful role for birth control pills in cutting ovarian cancer risk, the relationship between oral contraceptives and breast cancer risk was ambiguous. The authors said women and their health care providers should weigh the potential benefits of oral contraceptives (eg, reduction in ovarian cancer risk, avoidance of unintended pregnancy, and regulation of menstrual cycles) against the potential risks (such as blood clots or the possible increased risk of breast cancer). Also, evidence was insufficient to draw conclusions about the relationships between breastfeeding and tubal ligation, respectively, and breast cancer.
“Patients deserve better cancer-risk reduction options than surgically removing their healthy breasts and ovaries,” said co-author Susan Domchek, MD, executive director of the Basser Research Center for BRCA.