Abstract P039: Framework for genomic cancer risk assessment dissemination and implementation in Latin America: The GRACIAS (genetic risk assessment for cancer implementation and sustainment) study

Introduction: Lack of public insurance coverage for genetic testing and a limited trained genomic cancer risk assessment (GCRA) workforce are barriers to cancer screening and prevention and to understanding the genetic epidemiology of cancer in low/middle income countries (LMIC) in Latin America. Methods: We implemented an intervention that included professional education for clinicians in Mexico, Peru and Colombia, support from a community of practice and a federated consortium of collaborators, a versatile research registry with a dual purpose (research and clinical care) centralized relational database and pedigree drawing program (web-accessible), and economical NGS multigene panel tests (MGPT). We report here the outcomes of GCRA for 4181 probands (3170 breast, 301 ovarian, 965 other cancer, and 262 unaffected). Results: With a mean age of 45.2 y.o. (39.9 y.o. at breast cancer dx for carriers), a pathogenic variant (PV) was detected in 605 (14.5%) of 2,710 probands (BRCA testing only for 1387, MGPT for 1323): BRCA1 (n=250); BRCA2 (129); CHEK2 (24); PALB2 (20); ATM (14); TP53 (14); PTEN (6); CDH1 (5); MMR genes (62); RAD51C (6); and BRIP1 (3). We have documented growing reach (proportion of those eligible that access GCRA), increasing cascade testing (family member(s) tested (n=541) for 192/470 [40%] probands with a PV), and with median 2.2 years follow up, 209 risk reduction surgeries were performed. Summary: Remarkably, despite systemic limitations, integration of a skilled multidisciplinary team with access to genetic assays and practice support tools, community, and hospital outreach increased GCRA reach, and the expansion of cascade testing and performance of risk-appropriate surgeries reflect maturing prevention programs. Sustainment of progress requires increased multilevel efforts and establishment of GCRA as a supported standard of care, so the opportunity for prevention is not missed for vulnerable and underserved high-risk patients and families.

Citation Format: Jeffrey N. Weitzel, Julio Abugattas, Cynthia Villarreal-Garza, Adrian Daneri Navarro, Alicia Cock-Rada, Yenni Rodriguez, Pamela Mora-Alferez, Dione Aguilar, Azucena del Toro-Valero, Francisco Gutierrez-Delgado, Ana Ferrigno, Josef Herzog, Danielle Castillo, Gubidxa Gutierrez Seymour, Bita Nehoray, Kathleen R. Blazer, Maria E. Fernandez, Yanin Chavarri Guerra. Framework for genomic cancer risk assessment dissemination and implementation in Latin America: The GRACIAS (genetic risk assessment for cancer implementation and sustainment) study. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr P039.

LINC-21. PROGNOSTIC FACTORS AND SURVIVAL OF LOW-GRADE GLIOMAS IN CHILDREN AND ADOLESCENTS – A MULTICENTER STUDY IN PERU

BACKGROUND: Low-grade gliomas (LGG) are the most common central nervous system (CNS) tumors in children. Peru is an index country for the Global Initiative for Childhood Cancer (GICC). As part of the Initiative, a multidisciplinary brain tumor team was formed in 2020 that includes five national reference centers: National Institute of Neoplastic Diseases, National Children’s Health Institute-San Borja, National Children’s Health Institute-Breña, Edgardo Rebagliati Martins National Hospital and Guillermo Almenara Irigoyen National Hospital. This multicenter study sought to evaluate the survival and prognostic factors of patients younger than 18 years diagnosed with LGG, an index cancer for the GICC. METHODS: A retrospective study included all patients diagnosed with LGG in the five centers between 2014 and 2018. We analyzed clinical characteristics, histology, and treatment modalities. We used the Kaplan-Meier method for survival. RESULTS: 194 patients were registered; 136 patients were included. M/F ratio was 1.2, mean age 7 years old. The most frequent location was infratentorial (42.2%), supratentorial (34.9%), optic/chiasm/sellar (11%) and brainstem (11.9%). The most frequent histological types were pilocytic astrocytoma (61%), diffuse astrocytoma (10.3%), oligodendroglioma (5.2%), and other low-grade neoplasms (23.5%). Surgery was performed in 109 patients (83.2%). Chemotherapy alone was used in 17 (12.5%), while radiotherapy in 20 (14.7%). Overall survival at 5 years was 82.9% (95% CI 73.3 - 89.4). Age younger than 3 years (p=0.002), diffuse histological type (p=0.04), and location in the brainstem (p=0.001) were factors associated with a worse prognosis. CONCLUSIONS: Within the framework of the GICC, this work is one of the first steps to understand the current context of pediatric CNS tumor care in Peru. Although the reported survival rate is about the GICC goal of 60%, further improvements in care are needed to increase survival to level closer to high-resource setting and decrease long term morbidity.

[Microsatellite instability in patients with diagnostic of colorectal cancer]

OBJECTIVE

To determine the presence of microsatellite instability in patients with colorectal cancer using the molecular panel Bethesda and discuss its significance in patients with suspected hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch Syndrome.

MATERIALS AND METHODS

We worked with samples of peripheral blood and tumor tissue of 28 patients diagnosed with colorectal cancer referred to the Laboratory of Molecular Biology of the Instituto Nacional de Enfermedades Neoplasicas (INEN), Lima, with suspected of Lynch syndrome. DNA was extracted using kits of nucleic acid extraction of peripheral blood and paraffin-embedded tumor tissue. Five microsatellite markers of Bethesda panel were amplified: BAT25, BAT26, D2S123, D5S346 and D17S250, by polymerase chain reaction. IMS analysis was performed by electrophoresis on chip in the Bioanalyzer Agilent 2100.

RESULTS

Of the patients studied, 11 had high IMS(IMS-H) and one could not be fully ranked, staying as MSI-H / IMS-L. In all cases of IMS-H both BAT26 and BAT25 were unstable. The IMS-H in these patients indicates high probability of HNPCC or Lynch syndrome; it must be contrasted with the genetic analysis of MMR genes.

CONCLUSION

The technique allowed determine which patients have to continue with the study of system mismatch repair genes, for establish whether we facing to HNPCC or sporadic colorectal cancer.

Clinical and Molecular Features of Late Onset Huntington Disease in a Peruvian Cohort

BACKGROUND

Late onset cases of Huntington disease (HD), with onset ≥60 years, account for up to 20% of HD cases worldwide. Clinical features include mild motor dysfunction with slow progression and cognitive impairment, frequent absence of family history and low number of CAG repeats. The clinical and molecular features of late onset HD is still understudied in Latin America.

OBJECTIVES

To describe the clinical and molecular characteristics of late onset HD in a Peruvian cohort.

METHODS

An observational study was carried out by reviewing the HD registry at the Neurogenetics Research Center-INCN from 2000 to 2014. Genotyping of HTT gene …was confirmed using standard PCR and PAGE in accordance to protocols previously established.

RESULTS

Thirty-one late onset HD cases from 27 pedigrees were identified (9.42% of total HD cases, n = 329), 51.61% were male. Mean age at onset was 64.1 ± 4.2 and CAG repeats mean was 42.5 ± 2.5. We did not find significant correlation between age at onset and CAG repeats. 33.3% of cases were traced back to Cañete valley. Twenty-two cases had a positive family history, 14 of them with paternal transmission. Choreic movements and cognitive impairment were the main existing manifestations reported in this cohort, with lower frequency of psychiatric disturbances.

CONCLUSIONS

This report of late onset HD affected individuals shows a mild phenotype expression of the disease, associated with low range of CAG repeats and up to 30% of cases with absence of clear family history. Cañete valley remains the region with more cases.