Validity of models for predicting BRCA1 and BRCA2 mutations.

BACKGROUND: Deleterious mutations of the BRCA1 and BRCA2 genes confer susceptibility to breast and ovarian cancer. At least 7 models for estimating the probabilities of having a mutation are used widely in clinical and scientific activities; however, the merits and limitations of these models are not fully understood. OBJECTIVE: To systematically quantify the accuracy of the following publicly available models to predict mutation carrier status: BRCAPRO, family history assessment tool, Finnish, Myriad, National Cancer Institute, University of Pennsylvania, and Yale University. DESIGN: Cross-sectional validation study, using model predictions and BRCA1 or BRCA2 mutation status of patients different from those used to develop the models. SETTING: Multicenter study across Cancer Genetics Network participating centers. PATIENTS: 3 population-based samples of participants in research studies and 8 samples from genetic counseling clinics. MEASUREMENTS: Discrimination between individuals testing positive for a mutation in BRCA1 or BRCA2 from those testing negative, as measured by the c-statistic, and sensitivity and specificity of model predictions. RESULTS: The 7 models differ in their predictions. The better-performing models have a c-statistic around 80%. BRCAPRO has the largest c-statistic overall and in all but 2 patient subgroups, although the margin over other models is narrow in many strata. Outside of high-risk populations, all models have high false-negative and false-positive rates across a range of probability thresholds used to refer for mutation testing. LIMITATION: Three recently published models were not included. CONCLUSIONS: All models identify women who probably carry a deleterious mutation of BRCA1 or BRCA2 with adequate discrimination to support individualized genetic counseling, although discrimination varies across models and populations.

Characterization of BRCA1 and BRCA2 mutations in a large United States sample.

PURPOSE: An accurate evaluation of the penetrance of BRCA1 and BRCA2 mutations is essential to the identification and clinical management of families at high risk of breast and ovarian cancer. Existing studies have focused on Ashkenazi Jews (AJ) or on families from outside the United States. In this article, we consider the US population using the largest US-based cohort to date of both AJ and non-AJ families. METHODS: We collected 676 AJ families and 1,272 families of other ethnicities through the Cancer Genetics Network. Two hundred eighty-two AJ families were population based, whereas the remainder was collected through counseling clinics. We used a retrospective likelihood approach to correct for bias induced by oversampling of participants with a positive family history. Our approach takes full advantage of detailed family history information and the Mendelian transmission of mutated alleles in the family. RESULTS: In the US population, the estimated cumulative breast cancer risk at age 70 years was 0.46 (95% CI, 0.39 to 0.54) in BRCA1 carriers and 0.43 (95% CI, 0.36 to 0.51) in BRCA2 carriers, whereas ovarian cancer risk was 0.39 (95% CI, 0.30 to 0.50) in BRCA1 carriers and 0.22 (95% CI, 0.14 to 0.32) in BRCA2 carriers. We also reported the prospective risks of developing cancer for cancer-free carriers in 10-year age intervals. We noted a rapid decrease in the relative risk of breast cancer with age and derived its implication for genetic counseling. CONCLUSION: The penetrance of BRCA mutations in the United States is largely consistent with previous studies on Western populations given the large CIs on existing estimates. However, the absolute cumulative risks are on the lower end of the spectrum.

Predictors of participation in psychosocial telephone counseling following genetic testing for BRCA1 and BRCA2 mutations.

Although adjunctive educational and psychosocial programs are now being developed for BRCA1 and BRCA2 (BRCA1/2) mutation carriers, limited information is available about whether mutation carriers will want to receive such programs or about the characteristics of individuals who participate. The goals of the present study were to describe rates of completing a psychosocial telephone counseling (PTC) intervention that was offered to female BRCA1/2 mutation carriers and to identify sociodemographic and psychological factors associated with decisions to complete the intervention. Subjects were 66 BRCA1/2 mutation carriers who were randomized to receive a PTC intervention following receipt of genetic test results. Sociodemographic and psychological factors were evaluated before notification of assignment to the PTC intervention. Completion of the intervention was determined from study records. Overall, 75.8% of subjects completed the PTC intervention. Compared to unaffected subjects, those affected with breast and/or ovarian cancer were 76% less likely to complete the intervention [odds ratio (OR) = 0.24, 95% confidence interval (CI) = 0.06, 0.98, P = 0.05]. In addition, subjects with higher levels of cancer-specific distress [OR = 4.74, 95% CI = 1.02, 22.03, P = 0.05] and those with greater perceptions of social support [OR = 5.81, 95% CI = 1.29, 26.16, P = 0.02] were also most likely to complete the intervention. The results of this study suggest that while most BRCA1/2 mutation carriers are likely to complete an adjunctive psycho-educational program, personal history of cancer, cancer-specific distress, and perceptions of social support are likely to influence participation.

All in the family: evaluation of the process and content of sisters' communication about BRCA1 and BRCA2 genetic test results.

Despite the potential importance of family communication, little is known about the process and content of communicating BRCA1/2 test results to relatives. The objectives of this observational study were to describe the process and content of communicating BRCA1/2 test results to sisters, and to evaluate whether the proband's carrier status influenced communication outcomes. Participants were 43 women who were the first family member to have genetic testing (probands). Probands reported on communication outcomes for 81 sisters. Process and content variables were evaluated 1-month after receipt of BRCA1/2 test results using the Family Communication Questionnaire (FCQ). Overall, BRCA1/2 test results were communicated to 85% of sisters, and carriers communicated their results to significantly more sisters compared to uninformative (96% vs. 76%, FET = 0.02). The most important reason for communicating results was to provide genetic risk information; however, compared to uninformatives, carriers communicated their results to significantly more sisters to obtain emotional support (74%) and to get advice about medical decisions (42%) (FET = 0.001). Carriers also discussed the possibility of discrimination and recommendations for cancer management with significantly more sisters. Among sisters to whom BRCA1/2 test results were not communicated, the most important reason for not sharing test results was because of emotionally distant relationships. The results of this study suggest that probands are likely to quickly communicate their BRCA1/2 test results to relatives and that although needs for social support may motivate family communication, emotionally distant relationships may be a barrier to communication with relatives.