Increased Detection Of Germline Cancer Susceptibility Mutations Subsequent To Tumor Profiling.

e13613Background: In addition to guiding targeted therapy, tumor profiling may incidentally reveal germline mutations leading to the diagnosis of hereditary cancer predisposition. When somatic and germline analysis is performed in tandem, 4-13% of patients are found to carry a mutation in a cancer-susceptibility gene. However, the rate of pathogenic mutations is significantly higher (17.5%) when germline testing is performed subsequent to tumor profiling. We sought to examine the frequency and clinical significance of germline testing subsequent to tumor profiling when performed at separate laboratories. Methods: Retrospective review of a laboratory database revealed 175 germline test orders following reported external somatic tumor analysis between June 2014 and April 2017. A description of the patient’s tumor, including associated somatic mutations, was obtained from test requisitions. Germline targeted sequencing was performed with DNA isolated from blood or saliva. Pathogenic and likely pathogenic mut...