Molecular and pathological analyses of gastric stump cancer by next-generation sequencing and immunohistochemistry

Masahiro Watanabe,Takahiro Kinoshita,Akiko Tonouchi,Akio Kaito,Masato Nagino,Shizuki Sugita,Takeshi Kuwata,Masanori Tokunaga,Ayumi Setsuda

doi:10.1038/s41598-021-83711-1

Masahiro Watanabe, Takahiro Kinoshita + Show 7 more

Open Access

https://doi.org/10.1038/s41598-021-83711-1

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Abstract

Gastric stump cancer (GSC) has distinct clinicopathological characteristics from primary gastric cancer. However, the detailed molecular and pathological characteristics of GSC remain to be clarified because of its rarity. In this study, a set of tissue microarrays from 89 GSC patients was analysed by immunohistochemistry and in situ hybridisation. Programmed death ligand 1 (PD-L1) was expressed in 98.9% of tumour-infiltrating immune cells (TIICs) and 6.7% of tumour cells (TCs). Epstein–Barr virus (EBV) was detected in 18 patients (20.2%). Overexpression of human epidermal growth factor receptor 2 and deficiency of mismatch repair (MMR) protein expression were observed in 5.6% and 1.1% of cases, respectively. Moreover, we used next-generation sequencing to determine the gene mutation profiles of a subset of the 50 most recent patients. The most frequently mutated genes were TP53 (42.0%) followed by SMAD4 (18.0%) and PTEN (16.0%), all of which are tumour suppressor genes. A high frequency of PD-L1 expression in TIICs and a high EBV infection rate suggest immune checkpoint inhibitors for treatment of GSC despite a relatively low frequency of deficient MMR gene expression. Other molecular characteristics such as PTEN and SMAD4 mutations might be considered to develop new treatment strategies.

Highlights

Gastric stump cancer (GSC) has distinct clinicopathological characteristics from primary gastric cancer
We found that Programmed death ligand 1 (PD-L1) expression in tumour cells (TCs) (6.7%) of GSC was lower compared with that in TCs of primary gastric cancer (PGC) as reported previously (22.8%)[23] and that PD-L1 was expressed more frequently in tumour-infiltrating immune cells (TIICs) of GSC compared with those of PGC23
Because other clinical factors are known to be related to inflammation in the stomach and may induce PD-L1 expression in TC sand/or TIICs, we investigated the smoking status, drinking habits, helicobacter pylori infection, and adjuvant chemotherapy following initial gastrectomy (Supplementary Table 3)

Summary

Introduction

Gastric stump cancer (GSC) has distinct clinicopathological characteristics from primary gastric cancer. A high frequency of PD-L1 expression in TIICs and a high EBV infection rate suggest immune checkpoint inhibitors for treatment of GSC despite a relatively low frequency of deficient MMR gene expression Other molecular characteristics such as PTEN and SMAD4 mutations might be considered to develop new treatment strategies. Repeated destruction and regeneration of mucosal tissues occur more severely at the site of anastomosis, which can damage DNA12,13 and cause specific mutations Another possible carcinogenic factor is Epstein–Barr virus (EBV) infection that occurs in GSCs with higher frequencies (20–40%) compared with primary gastric cancer (PGC) (5–10%)[14,15,16]. We used immunohistochemistry (IHC), in situ hybridisation (ISH), and next-generation sequencing (NGS) to analyse the tissues of GSC patients by focusing on mutation profiles, protein expression, and EBV profiles

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