Abstract P6-08-29: Genetic counseling in patients with risk for hereditary breast cancer based on the NCCN guidelines for BRCA1/2 testing criteria in a private hospital center in Porto Alegre - Brazil

Abstract

Abstract Cancer risk assessment and genetic counseling is highly recommended when genetic testing is offered. Given this scenario, a private nonprofit hospital located in Porto Alegre - the Brazilian city with the highest incidence of breast cancer (crude rate estimated at 114.25/100,000 for 2018) - established a comprehensive breast cancer center (Núcleo Mama Moinhos, NMM). We investigated the genetic evaluation in patients with risk for hereditary breast cancer based on the NCCN criteria for Genetic testing. Was a retrospective cohort study that included patients with criteria from NCCN for genetic counseling during a period of 8 years (2011-2018). Table 1. Genetic counseling in patients with risk for hereditary breast cancer during a period of 8 years (2011-2018).Total patients with Genetic evaluation.525100%Without criteria for genetic testing 24145.9%Genetic Testing28353.9%• BRCA1/2 testing17963.2%• Genetic PANEL10436.7% Table 2. Patients with a pathogenic variant detected in a genetic testTotal patients with Genetic Testing283 (100%)BRCA1 pathogenic variant23 (8.1%)BRCA2 pathogenic variant14 (4.9%)Pathogenic variant detected in Genetic PANEL (BRCA1, BRCA2, PALB, RAD51C, TP53)7 (2.4%) Table 3. Patients with genetic pathogenic variant with or without breast cancer and prophylactic surgeryTotal patients39BRCA1 BRCA2 Others pathogenic variantUnderwent Prophylactic SurgeryTriple negative19 (48.7%)135-8HER2-positive2 (5.1%)1-1-Luminal9 (23.1%)45-4relevant family history without breast cancer9 (23.1%)5414 525 patients had criteria. We performed 283 genetic tests, divided into two groups: (1) BRCA1/2 analysis (63.2%; n=179/283), and (2) Genetic Panel (36.7%; n=104/283). Pathogenic variant were detected: BRCA1 (58.9%; n=23/39), BRCA2 (35.8%; n=14/39), and other genes (5.1%; n=2/39). We observe that 76.9% patients with a pathogenic variant identified (n=30/39) had breast cancer diagnose before testing, and 23.1% (n=9/39) patients had relevant family history. Triple negative (48.7%) was the most common type and the majority had BRCA1 pathogenic variant.Breast cancer is the most common cancer in women, and ten percent of these cancers are considered hereditary. Among them, 30% are attributed to germline pathogenic variant in BRCA1 and BRCA2 tumor suppressor genes. Other lower penetrance genes are also known, accounting together for up to 40% of the hereditary risk of breast cancer. Indicating genetic testing for a breast cancer patient is usually based on their family history, but in the absence of a family history of cancer, some women are candidates for testing based on the NCCN guidelines criteria. 1. NCCN clinical practice guidelines in oncology (NCCN guidelines). 2. van Marcke C, De Leener A, Berlière M, et AL. Routine use of gene panel testing in hereditary breast cancer should be performed with caution. Crit Rev Oncol Hematol. 2016 Dec;108:33-39. Results: 525 patients had criteria. We performed 283 genetic tests, divided into two groups: (1) BRCA1/2 analysis (63.2%; n=179/283), and (2) Genetic Panel (36.7%; n=104/283). Pathogenic variant were detected: BRCA1 (58.9%; n=23/39), BRCA2 (35.8%; n=14/39), and other genes (5.1%; n=2/39). We observe that 76.9% patients with a pathogenic variant identified (n=30/39) had breast cancer diagnose before testing, and 23.1% (n=9/39) patients had relevant family history. Triple negative (48.7%) was the most common type and the majority had BRCA1 pathogenic variant.Breast cancer is the most common cancer in women, and ten percent of these cancers are considered hereditary. Among them, 30% are attributed to germline pathogenic variant in BRCA1 and BRCA2 tumor suppressor genes. Other lower penetrance genes are also known, accounting together for up to 40% of the hereditary risk of breast cancer. Indicating genetic testing for a breast cancer patient is usually based on their family history, but in the absence of a family history of cancer, some women are candidates for testing based on the NCCN guidelines criteria. Citation Format: Maira Caleffi, Yulieth Acevedo Perez, Tabata Machado, Luis Sussela, Ana Paula Gomes, Osvaldo Artigalás. Genetic counseling in patients with risk for hereditary breast cancer based on the NCCN guidelines for BRCA1/2 testing criteria in a private hospital center in Porto Alegre - Brazil [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 P6-08-29.