Among women who carry BRCA1 or BRCA2 mutations, the type and exact location of the mutation influences the risk it confers for breast and ovarian cancer, according to a report published online April 7 in JAMA.
Investigators examined differences in cancer risks by analyzing data in the Consortium of Investigators of Modifiers of BRCA (CIMBA), a collection of clinical and genetic information for carriers of disease-associated BRCA mutations in 33 countries.
For this study, data were assessed for 19,581 women with BRCA1 mutations and 11,900 women with BRCA2 mutations for whom there was sufficient information to estimate hazard ratios. The types of mutations included nonsense, frame shift, in-frame, missense, splicing, rearrangement, premature termination codons, and nonsense-mediated decay mutations, said Timothy R. Rebbeck, Ph.D., of Abramson Cancer Center and the Center for Clinical Epidemiology and Biostatistics at the University of Pennsylvania, Philadelphia, and his associates.
Among the study participants with BRCA1 mutations, 9,052 women (46%) developed breast cancer, 2,317 (12%) developed ovarian cancer, and 1,041 (5%) developed both breast and ovarian cancer. Among the women with BRCA2 mutations, 6,180 (52%) developed breast cancer, 682 (6%) developed ovarian cancer, and 272 (2%) developed both breast and ovarian cancer. A woman’s risk for cancer differed significantly according to the type of BRCA1 or BRCA2 mutation she carried and according to the location of the mutation on the nucleotide, the investigators said (JAMA 2015 April 7 [doi:10.1001/jama.2014.5985]).
Further research is needed to determine the absolute risks of cancer associated with each mutation and “to better understand what level of risk difference will change decision-making and standards of care, such as preventive surgery” for BRCA1 and BRCA2 carriers, Dr. Rebbeck and his associates added.
This study was funded primarily by Cancer Research UK and also was supported by the U.S. National Institutes of Health, the Basser Research Center at the University of Pennsylvania, the Breast Cancer Research Foundation, and the Rooney Family Foundation. Dr. Rebbeck reported having no financial disclosures; his associates reported numerous ties to industry sources.