Abstract A033: Gene-specific risk of syndrome-associated cancers in first-degree relatives of pancreatic cancer patients with pathogenic/likely pathogenic variants
Authors: Chen Xuan , Rabe Kari , Meyer Margaret , Kemppainen Jennnifer , Horibe Masayasu , Chandra Shruti , Majumder Shounak , Petersen Gloria 
Published: November 2022

Abstract
Increased pancreatic cancer (PC) risk in first-degree relatives (FDRs) of PC patients with germline pathogenic/likely pathogenic variants (PLPV) is a motivator for cascade genetic testing. To date, unbiased FDR risk estimates for gene-specific risks of genetic cancer syndrome-associated cancers are unknown. These estimates would enhance genetic counseling of at-risk FDRs in families where the PC proband has been found to carry a PLPV. Study Aim: To objectively quantify gene-specific risks of six relevant cancers among FDRs of PC patients with germline PLPV in ATM, BRCA1, BRCA2, CDKN2A, MLH1, MSH2, MSH6, PALB2, and PMS2. Methods: In the prospective, clinic-based Mayo Clinic Biospecimen Resource for Pancreas Research registry, 4,562 PC patients had previously undergone germline genetic testing for pancreatic cancer-associated genes through either research studies or clinical testing. Of these, 234 PC probands were found to carry PLPV among 9 genes of interest and had provided detailed demographic and cancer data on their FDRs by questionnaire. We focused on six cancer types (ovary, breast, uterus, pancreas, colon, and malignant melanoma) in FDRs as reported by the probands. Standardized incidence ratios estimated risk by gene of six cancers among FDRs of PC patients carrying PLPV. Results: 1,670 FDRs (mean age 58.1+17.8SD; 48.9% female) were included in the study. We found significantly increased risk of ovarian cancer in female FDRs of PC probands who carry PLPV in BRCA1 (SIR 9.49, 95%CI:3.06-22.14) or BRCA2 (3.72, 95%CI:1.36-8.11), and breast cancer risks were higher with BRCA2 (2.62, 95%CI:1.89-3.54). Uterine cancer risk was increased in FDRs of PC probands who carry PLPV for Lynch Syndrome mismatch repair (MMR) (6.53, 95%CI:2.81-12.86). PC risk was also increased (ATM 4.53, 95% CI:2.69-7.16; BRCA2 3.45, 95%CI:1.72-6.17; CDKN2A 7.38, 95%CI:3.18-14.54; PALB2 5.39, 95%CI:1.45-13.79). Increased colon cancer risk was observed in FDRs of probands who carried MMR PLPV (5.83, 95%CI:3.70-8.75), while melanoma risk was elevated for FDRs of probands with CDKN2A PLPV (7.47, 95%CI:3.97-12.77). Conclusion: PLPV in nine syndrome-associated genes in PC probands are associated with increased risk of six cancers in FDRs in PC families. The findings underscore the importance of risk estimation of various other cancers in PC families for screening, early detection, and intervention. The gene-specific quantified cancer risks for FDRs of PC patients with syndrome-associated germline PLPV can inform counseling regarding extra-PC risks when considering cascade genetic testing.
Citation Format: Xuan Chen, Kari Rabe, Margaret Meyer, Jennnifer Kemppainen, Masayasu Horibe, Shruti Chandra, Shounak Majumder, Gloria Petersen. Gene-specific risk of syndrome-associated cancers in first-degree relatives of pancreatic cancer patients with pathogenic/likely pathogenic variants [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A033.