Abstract P6-08-34: Genetic testing for hereditary breast cancer in Brazilian public health system: The experience of tumor board reference in a cancer center

Abstract

Abstract Introduction: In Brazil, genetic testing for hereditary cancer predisposition syndromes, including Hereditary Breast Cancer (HBC), is not covered by the public health system (SUS) and was only incorporated in most private health insurance (PHI) plans after 2013. Nonetheless, considering that only 22% of the Brazilian population has access to private health system and the high cost of genetic testing in private laboratories, the majority of Brazilian women at risk for HBC do not have access to a genetic diagnosis. In this context, we have implemented at A.C.Camargo Cancer Center (ACCCC – a reference Cancer Center in Brazil which serves both the private and public health systems) a pilot program that offers genetic testing for SUS patients at risk for HBC. The goal of this study is to present the adopted clinical criteria and the corresponding detection rate of pathogenic variants in HBC genes observed in our cohort in comparison to detection rates observed in private health scenario. Methods: Since 2018, 34 cases of breast cancer patients from SUS under medical follow-up at ACCCC and at risk for HBC were discussed in multidisciplinary Tumor Board meetings. The Tumor Board team consists of health care professionals from different specialties, including medical oncologists, surgeons, pathologists, molecular biologists, and clinical geneticists. The clinical criteria defined for referring patients to genetic testing were: (1) personal history of triple negative breast cancer (TNBC) in any age; (2) personal history of non-TNBC developed before 30 years old, positive family history of cancer, and a PENN II model prediction of >15% risk in carry a BRCA1/2 mutation; and (3) personal history of BC in any age and a PENN II model prediction of >30% risk in carry a BRCA1/2 mutation. Detection rates of SUS patients were compared to BRCA1/2 results obtained during the same period from the ACCCC Laboratory of Genomics Diagnostics that serves manly PHI and private patients. Genetic tests were performed using different gene panels containing 26 or 94 genes. Results: Pathogenic (P) and likely pathogenic (LP) variants were detected in 38% of SUS patients (13/34), with a higher proportion of BRCA1 carriers (69% - 9 patients) than of BRCA2 (1 patient). Aside BRCA1/2 mutations that were detected in 10 patients (29%), P/LP variants were also identified in BRIP1, CHEK2, and PALB2 (1 patient each). The rate for BRCA1/2 P/LP variants in PHI cohort was 9.8% (23/234 patients), with a lower proportion of BRCA1 carriers (22%) than of BRCA2 (40%). It was identified a high rate of P/LP variants in TNBC from SUS cohort (62% - 10/16 cases) and a marked association of BRCA1 and TNBC, with 80% (8/10) of hereditary TNBC having BRCA1 mutations. The mean turnaround time for genetic test results was 4 months, varying from 2 to 8 months. From 11 patients with P/LP variants that already received the genetic test result, 5 underwent prophylactic contralateral mastectomy and/or bilateral salpingo-oophorectomy. Conclusions: The introduction of genetic testing for HBC made possible to tailor preventative measures for women at high risk, including prophylactic surgery and screening protocols. However, in many developing countries, the high cost of genetic tests and the lack of national policies prevent its application in clinical practice for the majority of the population. By defining more stringent clinical criteria for HBC genetic test, we detected a mutation rate three times as high as that detected in the private health scenario. With the continuity our study, we expect to contribute to the development of national standards for HBC screening and to encourage the implementation of consistent and cost-effective genetic testing under the real-life conditions of our public health system, maximizing the benefit for the population with the available resources. Citation Format: Dirce M Carraro, Giovana T Torrezan, Karina M Santiago, Maria\ Nirvana da Cruz Formiga, Solange M Sanches, Fabiana BA Makdissi, Breast Cancer Tumor Board Team. Genetic testing for hereditary breast cancer in Brazilian public health system: The experience of tumor board reference in a cancer center [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 P6-08-34.