Background Previous studies have reported additional cancers associated with BRCA mutations; however, type, magnitude of risk, and gender differences remain to be clarified. The purpose of this study was to evaluate the incidence of cancers other than breast and ovarian cancer in known mutation carriers. Methods An institutional review board approved study identified 1072 patients who had genetic counseling at our institution and tested positive for a deleterious BRCA mutation. The expected number of cancer cases was calculated from the number of individuals in the study sample multiplied by the general population cancer incidence rates. The expected and observed number of cases were calculated in 5 year intervals to accommodate different age-related incidence rates. Standardized incidence ratios (SIRs) for each cancer type were calculated. Results We identified 1177 cancers in the 1072 mutation carriers comprising 30 different cancer types. Individuals with a BRCA1 mutation did not have a significant increase in cancers other than breast and ovarian; however, a trend in melanoma was observed. Individuals with a BRCA2 mutation had a significantly higher number of observed cases compared to expected cases for pancreatic cancer (SIR = 21.7, 95%CI = 13.1–34.0, p value <0.001) in both men and women and prostate cancer in men (SIR = 4.9, 95%CI = 2.0–10.1, p value =0.002). Conclusions The results of this study uphold the current recommendations for HBOC screening of cancers other than breast and ovarian by the National Comprehensive Cancer Network. Larger cohorts and collaborations are needed to further verify these findings.
IMPORTANCE Variant reclassification is an important component of hereditary cancer genetic testing; however, there are few published data quantifying the prevalence of reclassification. OBJECTIVE Retrospective cohort study of individuals who had genetic testing from 2006 through 2016 at a single commercial laboratory. DESIGN, SETTING, AND PARTICIPANTS A retrospective cohort of individuals who had genetic testing between 2006 and 2016 at a single commercial laboratory was assessed. Variants were classified as benign, likely benign, variant of uncertain significance, likely pathogenic, or pathogenic. Retrospective chart reviews were conducted for patients from the University of Texas Southwestern (UTSW) Medical Center. EXPOSURES Hereditary cancer genetic testing. MAIN OUTCOMES AND MEASURES Frequency of and time to amended reports; frequency and types of variant reclassification. RESULTS From 2006 through 2018, 1.45 million individuals (median [interquartile range] age at testing, 49 years [40.69-58.31 years], 95.6% women) had genetic testing, and 56.6% (n = 821 724) had a personal history of cancer. A total of 1.67 million initial tests were reported and 59 955 amended reports were issued due to variant reclassification. Overall, 6.4% (2868 of 44 777) of unique variants were reclassified. Reclassification to a different clinical category was rare among unique variants initially classified as pathogenic or likely pathogenic (0.7%, 61 of 9112) or benign or likely benign (0.2%, 15 of 8995). However, 7.7% (2048 of 26 670) of unique variants of uncertain significance were reclassified: 91.2% (1867 of 2048) were downgraded to benign or likely benign (median time to amended report, 1.17 years), 8.7% (178 of 2048) were upgraded to pathogenic or likely pathogenic variants (median time to amended report, 1.86 years). Because most variants were observed in more than 1 individual, 24.9% (46 890 of 184 327) of all reported variants of uncertain significance were reclassified. CONCLUSIONS AND RELEVANCE Following hereditary cancer genetic testing at a single commercial laboratory, 24.9% of variants of uncertain significance were reclassified, which included both downgrades and upgrades. Further research is needed to assess generalizability of the findings for other laboratories, as well as the clinical consequences of the reclassification as a component of a genetic testing program.
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