Initial Results of Multigene Panel Testing for Hereditary Breast and Ovarian Cancer and Lynch Syndrome.

Multigene panel testing for hereditary cancer risk has recently become commercially available; however, the impact of its use on patient care is undefined. We sought to evaluate results from implementation of panel testing in a multidisciplinary cancer center. We performed a retrospective review of consecutive patients undergoing genetic testing after initiating use of multigene panel testing at Loma Linda University Medical Center. From February 13 to August 25, 2014, 92 patients were referred for genetic testing based on National Comprehensive Cancer Network guidelines. Testing was completed in 90 patients. Overall, nine (10%) pathogenic mutations were identified: five BRCA1/2, and four in non-BRCA loci. Single-site testing identified one BRCA1 and one BRCA2 mutation. The remaining mutations were identified by use of panel testing for hereditary breast and ovarian cancer. There were 40 variants of uncertain significance identified in 34 patients. The use of panel testing more than doubled the identification rate of clinically significant pathogenic mutations that would have been missed with BRCA testing alone. The large number of variants of uncertain significance identified will require long-term follow-up for potential reclassification. Multigene panel testing provides additional information that may improve patient outcomes.

Underreporting of Gastrointestinal Stromal Tumors: Is the True Incidence Being Captured?

BACKGROUND: Hospital cancer registries are only required to report gastrointestinal stromal tumors (GISTs) if labeled malignant or metastatic, leading to potential loss of cases in national cancer registries. Our objective was to determine whether GISTs are underreported in the US. METHODS: Retrospective review of pathology reports between 2010 and 2013 with diagnosis of GIST was performed at two academic medical centers. Recurrent GISTs were excluded. Pathology reports were cross-referenced to cases reported by each cancer registry. Risk for metastasis/death was determined according to National Comprehensive Cancer Network (NCCN) guidelines. RESULTS: Forty-nine cases of non-recurrent GIST were identified. Only 19/49 (38.8%) cases were reported. None of the 30 non-reported cases were labeled malignant/metastatic on final pathology. To illustrate malignant potential, these tumors were risk stratified. Most (60%) of the non-reported cases were low risk, but there were 4 (13.3%) cases each in the intermediate, high, and unknown risk groups. Additionally, 7/30 (23.0%) cases were treated with tyrosine kinase inhibitors, highlighting clinical concern of malignant GIST. CONCLUSIONS: Our results show that nearly two thirds of GIST cases have been underreported, suggesting that current reporting practices underestimate its true incidence. Revision of reporting guidelines may result in a more accurate estimation of the US disease burden of GIST.