Abstract 3323: The feasibility for detecting hereditary genetic findings of familial gastric cancer
Authors: Nishimura Sadaaki 
Published: August 2019

Abstract
Background: Multiplex gene panel tests using next-generation sequencing has currently been clinically available for various cancer patients including gastric cancer in Japan. The original purpose of the Multiplex gene panel tests is to find actionable genetic alterations which might correlate with promising therapeutic antitumor drugs. Accordingly, secondary genetic findings as germline mutation which is associated with hereditary disease may also be detectable by the Multiplex gene panel tests. It has been reported that familial cancers represent around 5%–10% of all cancer patients. Gastric cancer is one of popular cancers in Japan. The prediction of patients with familial gastric cancer (FGC) before the multiplex gene panel tests might be important for the gene consultation for the patients and their family.
Objective: The aim of study is to clarify the characteristic clinico-pathologic features of FGC to predict the possibility of hereditary gastric cancer.
Patients and Methods: A total of 2301 gastric cancer patients who received gastrectomy at our department was enrolled in this study. We classified FGCs into 2 categories by modification of International Gastric Cancer Linkage Consortium (IGCLC) which excluded pathogenic types, as follows, group A: gastric cancer in an individual under the age of 40; group B: two gastric cancer cases in a family regardless of age. In contrast, the most gastric cancers were sporadic, which was classified as group C. The clinicopathological factors including E-cadherin and p53 expression by immunostaining, was retrospectively compared among 3 groups.
Results: One hundred and fifty-two cases (6.6%) of 2301 patients were classified as FGCs (group A: 71 cases; group B: 81 cases), whereas the remaining 2149 patients were classified as group C (93.4%). Female (43.4%) and diffuse-type gastric cancer (57.2%) was significantly (p&lt;0.001) more frequent in FGCs than that (30.5% and 42.5%) in group C. The significant difference (p&lt;0.05) of clinicopathological variables between group A (n=71) and B (n=81) was found in the rates of female (52.1% vs 35.8%), diffuse-type (83.1% vs 34.5%), and T4 status (38.0% vs 17.3%), respectively. There was also significant difference (p&lt;0.05) in the rates of female (52.1% vs 30.5%), diffuse-type (83.1% vs 42.5%) and Borrmann type 4 (15.5% vs 6.8%) between group A and C. No significant difference was found in clinicopathological variables between group B and C. No statistical correlation of E-cadherin loss between 3 groups. In this study, 2 cases were found in which p53 expression was positive for all cells.
Conclusion: Young age (&lt;40 years) and female patients with diffuse-type gastric cancer might have a high risk for FGC. It is necessary to take into consideration of hereditary gastric cancer when the multiplex gene panel test is performed for the young female gastric cancer patients with diffuse-type cancer.
Citation Format: Sadaaki Nishimura. The feasibility for detecting hereditary genetic findings of familial gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3323.