Abstract P6-08-32: Genetic variation and the role of multi-gene testing for hereditary breast cancer: A single institution experience

Abstract

Abstract Introduction: The introduction of multi-gene testing for hereditary forms of breast cancer has changed the clinical approach to genetic testing for breast cancer patients. Recent consensus guideline now recommends genetic testing for all patients with a personal history of breast cancer and updated testing to those who have had negative germline BRCA 1 and 2 testing. This is a single institutional experience regarding the use and outcomes of multi-gene testing and updated testing. Methods: This is a retrospective analysis of germline multi-gene testing for breast cancer patients at our institution. Information on tumor histology, personal and family history of cancer, age at diagnosis, and genetic testing information was obtained through records review. Results: Between January 1, 2015 and December 31, 2018, 1568 breast cancer patients were diagnosed or treated at our institution. Of those, 26% of the patients had genetic results (age range 23-87; median age 52; <1% Male; 88% non-Hispanic whites, 8% blacks, 2% Asians, 2% Hispanics). Eight percent of the patients were found to carry a pathogenic variant that the NCCN guidelines designated as sufficient evidence to have an increased risk for breast cancer. Of those, only 3.4% were BRCA 1 and 2 mutations. The prevalent pathogenic variants found in multi-gene testing were BRCA 1/ 2 (3.4%), CHEK2 (2.2%), PALB2 (1%), TP53 (1%), PMS2 (1%), MYTYH (0.74%), FANCC (0.25%), ATM (0.25%), MSH2 (0.25%), MSH6 (0.25%), NBN (0.25%), and RAD51C (0.25%). Fifteen patients had initial testing looking only for the presence of germline BRCA 1 and 2 mutations. Of those, updated expanded testing identified an additional two patients who carried a pathogenic variant that was previously unidentified. Conclusion: Multi-gene testing and expanded panel testing of all breast cancer patients could increase the detection of pathogenic variants and may have a potential clinical impact for patients and their family. Further understanding of genetic patterns and variation in multi-gene testing is needed. Increasing public awareness and decreasing the cost of genetic testing are also important to improve the rates of multi-gene testing. Citation Format: Kit Yu Lu, Meagan Smith, Julia Verbiar, Haleigh Minor, Jennifer Lapse, Latesha Blair, Lisa Torp. Genetic variation and the role of multi-gene testing for hereditary breast cancer: A single institution experience [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-32.