Abstract P4-06-17: Expanded panel testing in patients with breast or ovarian cancer in a rural familial cancer program

Abstract

Abstract Objective: We sought to investigate our center's experience with multi-gene panel testing in breast and ovarian cancer patients from a largely rural catchment area. Our goal was to identify predictors of pathogenic variants and assess indicators for expanded genetic testing. Methods: We conducted a retrospective review of breast and ovarian cancer patients who underwent panel testing between May 2011 and April 2016. A variety of commercial gene panels were used with variant classification determined by the individual laboratory. Differences in patient demographics, age of first cancer diagnosis, number of genes tested and tumor characteristics including hormone/HER2 status, histology, differentiation, tumor size and AJCC staging classification were analyzed among pathogenic variant positive, negative, and VUS patient subsets with a chi-square test and one-way ANOVA. Results: We identified 215 patients who underwent panel testing: the average age of patients was 52.9 ± 12 with first cancer onset at 47 ± 12; 27% of patients had undergone prior single-gene testing; 7% of patients had ovarian cancer and 93% of patients had breast cancer. VUS were detected in 18.1% of patients and pathogenic variants were detected in 9.3% of patients. Of the 20 pathogenic variants identified, 1 was detected in BARD1, 2 in BRIP1, 3 in MUTYH, 5 in CHECK2, 2 in BRCA1, 2 in BRCA2, 3 in ATM, 1 in PALB2 and 1 in PMS2. In our breast cancer cohort, there was a statistical difference (p=.03) between patients with VUS, pathogenic variants and negative testing in respect to hormone and HER2 status. Most pathogenic variants (75%) were in patients who were HER2 negative, with the majority of VUS detected in patients who were hormone receptor positive (66%). Between the groups, there were no differences in histology, tumor differentiation, size or AJCC stage classification. However, individuals with pathogenic variants tended to have a younger age of first cancer diagnosis, have higher grade disease and have triple negative tumors. Conclusions: Specific tumor patterns (that is, HER2 negative or triple negative pathology) may be important indicators for genetic testing in breast cancer patients. Expanded panel testing should be considered in patients with a younger age of cancer diagnosis, higher grade disease and triple negative tumors. Citation Format: Hermel DJ, McKinnon WC, Colello L, Greenblatt MS, Wood ME. Expanded panel testing in patients with breast or ovarian cancer in a rural familial cancer program [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-06-17.