A Danish national effort of BRCA1/2 variant classification

Longitudinal outcomes with cancer multigene panel testing in previously tested BRCA1/2 negative patients

Although multigene panel testing (MGPT) is increasingly utilized in clinical practice, there remain limited data on patient-reported outcomes. BRCA 1/2 negative patients were contacted and offered MGPT. Patients completed pre- and posttest counseling, and surveys assessing cognitive, affective and behavioral outcomes at baseline, postdisclosure and 6 and 12 months. Of 317 eligible BRCA1/2 negative patients who discussed the study with research staff, 249 (79%) enrolled. Decliners were more likely to be older, non-White, and recruited by mail or email. Ninety-five percent of enrolled patients proceeded with MGPT. There were no significant changes in anxiety, depression, cancer specific distress or uncertainty postdisclosure. There were significant but small increases in knowledge, cancer-specific distress and depression at 6-12 months. Uncertainty declined over time. Those with a VUS had significant decreases in uncertainty but also small increases in cancer specific distress at 6 and 12 months. Among those with a positive result, medical management recommendations changed in 26% of cases and 2.6% of all tested. Most BRCA1/2 negative patients have favorable psychosocial outcomes after receipt of MGPT results, although small increases in depression and cancer-specific worry may exist and may vary by result. Medical management changed in few patients.

Population frequencies of pathogenic alleles of BRCA1 and BRCA2: analysis of 173 Danish breast cancer pedigrees using the BOADICEA model

The Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA) calculates the probability that a woman carries a pathogenic variant in BRCA1 or BRCA2 based on her pedigree and the population frequencies of pathogenic alleles of BRCA1 (0.0006394) and BRCA2 (0.00102) in the United Kingdom (UK). BOADICEA allows the clinician to define the population frequencies of pathogenic alleles of BRCA1 and BRCA2 for other populations but only includes preset values for the Ashkenazy Jewish and Icelandic populations. Among 173 early-onset breast cancer pedigrees in Denmark, BOADICEA discriminated well between carriers and non-carriers of pathogenic variants (area under the receiver operating characteristics curve: 0.81; 95% CI 0.74-0.86) but underestimated the frequency of carriers of pathogenic variants in BRCA1 or BRCA2 as measured by the observed-to-expected ratio (O/E 1.83; 95% CI 1.18-2.84). This reflects findings from older studies of BOADICEA in UK, German, Italian, and Chinese populations, all accounting for the different calibration for different carrier probabilities. To improve the performance of BOADICEA for non-UK populations, we developed a method to derive population frequencies of pathogenic alleles of BRCA1 and BRCA2. Compared to the UK population frequencies, we estimated the Danish population frequencies of pathogenic alleles to be higher for BRCA1 (0.0015; 95% CI 0.00064-0.0034) and lower for BRCA2 (0.00052; 95% CI 0.00018-0.0017) after adjusting for the different calibration of BOADICEA for different carrier probabilities. Incorporating additional population frequencies into BOADICEA could improve its performance for non-UK populations.