The benefit of pancreatic cancer surveillance in carriers of germline BRCA1/2 pathogenic variants

BACKGROUND

Surveillance of high-risk individuals for pancreatic ductal adenocarcinoma (PDAC) is recommended. This study aimed to determine the prevalence and outcomes of PDAC and its precursor lesions in BRCA1/2 pathogenic variants (PVs) carriers undergoing pancreatic surveillance.

METHODS

A retrospective multicenter cohort study of pancreatic surveillance outcomes in Israeli BRCA1/2 carriers preferably with a family history of PDAC.

RESULTS

A total of 180 asymptomatic carriers participated in the screening programs, including 57 (31.7%) with BRCA1 PVs, 121 (67.2%) with BRCA2 PVs, and 12 (6.6%) with PVs in BRCA1/2 and other genes, for a median follow-up period of 4 years. Ninety-one individuals (50.5%) fulfilled the International Cancer of the Pancreas Screening (CAPS) criteria for surveillance whereas 116 (64.4%) fulfilled the American College of Gastroenterology (ACG) criteria. There were four cases of adenocarcinoma and four cases of grade 1-neuroendocrine tumor (G1-NET). All were BRCA2 carriers, and two had no family history of PDAC. Three cancer patients were at resectable stages (IA, IIA, IIB) whereas one had a stage IIIB tumor. Of the G1-NET cases, one had surgery and the others were only followed. Success rate for detection of confined pancreatic carcinoma was thus 1.6% (three of 180) in the whole cohort, 1.6% (two of 116) among individuals who fulfilled ACG criteria and 2.2% (two of 91) in those fulfilling CAPS criteria for surveillance.

CONCLUSIONS

Despite the low detection rate of PDAC and its' high-risk neoplastic precursor lesions among BRCA1/2 carriers undergoing pancreatic surveillance, 75% of cancer cases were detected at a resectable stage.

The Diagnostic Yield and Implications of Targeted Founder Pathogenic Variant Testing in an Israeli Cohort

Founder pathogenic variants (PVs) are prevalent in Israel. This study investigated the current practice of offering cancer patients two-step genetic testing, starting with targeted testing for recurring founder PVs, followed, if negative, by next-generation sequencing. A total of 2128 subjects with cancer or a positive family history underwent oncogenetic testing with a panel of 51 recurring PVs at a tertiary medical center in March 2020-January 2023. Those with a known familial PV (n = 370) were excluded from the analysis. Among the remainder, 128/1758 (7%) were heterozygous for at least one variant, and 44 (34%) carried a PV of medium-high penetrance (MHPV). Cancer was diagnosed in 1519/1758 patients (86%). The diagnostic yield of founder MHPV testing was 2% in cancer patients and 4% in healthy individuals with a positive family history. It was higher in Ashkenazi Jews than non-Ashkenazi Jews and Arabs, but not over 10% for any type of cancer, and it was significantly higher in younger (<40 years) than older (>50 years) individuals (7% vs. 1%). Eighty-four of the heterozygotes (66%), mostly Ashkenazi Jews, harbored a low-penetrance variant (LPV) not associated with the diagnosed cancer, usually APC c.3902T>A. These findings question the advantage of two-step testing. LPVs should not be included in targeted testing because this can lead to an overestimation of the yield, and their detection does not preclude further comprehensive testing.

[GENOTYPE-PHENOTYPE CORRELATIONS BY SPECIFIC FOUNDER VARIANTS IN BRCA IN ISRAELI WOMEN]

INTRODUCTION

Hereditary breast and ovarian cancer (HBOC) is predominantly accounted for by pathogenic variants (PVs) in BRCA1/BRCA2 genes. Population screening for recurring PVs in Ashkenazi Jews (AJ) was incorporated into the Israeli health basket in 2020, increasing the identification of BRCA carriers. Information on cancer risks for each PV in Israel is limited.

AIMS

To assess genotype phenotype correlations of recurring BRCA PVs in Israeli carriers.

METHODS

A retrospective cohort of 3,478 BRCA carriers followed-up in 12 medical centers, comprising the HBOC Consortium, formed the basis of the study. Data were collected using the electronic database, and analyzed by Chi square, t-tests and Kaplan-Meier survival analysis.

RESULTS

Overall, 2145 BRCA1, 1131 BRCA2, and 22 double heterozygote PV carriers were analyzed. BRCA1 carriers had more cases of cancer (53.1% vs. 44.8%, p<0.001), ovarian cancer (OC) (17.1% vs. 10.6%, p<0.001), younger age at breast cancer (BC) (45.4 ±11.6SD years vs. 49.1 ±11.1SD years, p<0.001) and OC diagnosis (52.8 ±10.1SD yrs. vs. 61±10.6SD yrs. p<0.001), and more family history of BC (64.5% vs. 59.0%, p<0.001) and OC (36.7% vs. 27.3%, p<0.001) compared with BRCA2 carriers. Carriers of BRCA15382insC had more BC and less OC than BRCA1185delAG: 46.4% vs. 38.6% and 12.9% vs. 17.6% (p<0.04), respectively.

CONCLUSIONS

In our population, similar to others, BRCA1 carriers have higher cancer rates and earlier age at diagnosis compared with BRCA2 carriers. The two recurring BRCA1 PVs have different risks: 5382insC carriers had more BC; 185delAG carriers had more OC. Risk-reducing measures should be based on variant-specific cancer risk.

A recurrent pathogenic BRCA2 exon 5-11 duplication in the Christian Arab population in Israel

Germline pathogenic variants (PVs) in BRCA1/BRCA2 are well-established risk factors for breast cancer (BC) and/or ovarian cancer (OC). Founder PVs have been described in BRCA1/ BRCA2 in several genetic isolates. The Christian Arab population in the Middle East is a relatively isolated ethnic group, yet founder, or recurrent BRCA1/BRCA2 PVs have not been reported in this population. In this study we describe PVs detected in cancer susceptibility genes among a cohort of Christian Arabs from Israel. We reviewed patient records from the Oncogenetic clinic at Rambam Health Care Campus during the years 2013- mid 2020. Thirty-five unrelated Christian Arab patients, with personal or family history of BC and/or OC underwent BRCA1/BRCA2 (14/35) testing or cancer gene panel testing (21/35) as part of their diagnostic workup. Three clinically significant variants in BRCA2, CHEK2 and RAD51C were found in 7/35 patients (20%). A recurrent duplication of the BRCA2 genomic region, encompassing exons 5-10 and the 5' portion of exon 11, was found in 5/33 (15.2%) patients for whom copy number variants (CNVs) analysis was performed. We identified a recurrent pathogenic BRCA2 duplication in Christian Arab patients with a personal/ family history of BC and/or OC. Our findings emphasize the importance of inclusion of CNVs analysis in BRCA1/BRCA2 genetic testing, and specifically for Christian Arab patients suspected of hereditary BC and/or OC.