Basic Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Feb 26, 2019; 7(4): 419-430
Published online Feb 26, 2019. doi: 10.12998/wjcc.v7.i4.419
Formalin fixation on HER-2 and PD-L1 expression in gastric cancer: A pilot analysis using the same surgical specimens with different fixation times
Keita Kai, Yukie Yoda, Atsushi Kawaguchi, Akimichi Minesaki, Hironori Iwasaki, Shinichi Aishima, Hirokazu Noshiro
Keita Kai, Shinichi Aishima, Department of Pathology, Saga University Hospital, Saga 849-8501, Japan
Yukie Yoda, Hironori Iwasaki, Hirokazu Noshiro, Department of Surgery, Saga University Faculty of Medicine, Saga 849-8501, Japan
Atsushi Kawaguchi, Center for Comprehensive Community Medicine, Saga University Faculty of Medicine, Saga 849-8501, Japan
Akimichi Minesaki, Shinichi Aishima, Department of Pathology and Microbiology, Saga University Faculty of Medicine, Saga 849-8501, Japan
Akimichi Minesaki, Department of Otolaryngology - Head and Neck Surgery, Saga University Faculty of Medicine, Saga 849-8501, Japan
Author contributions: Kai K conceived and designed the study. Kai K, Yoda Y, Kawaguchi A, Minesaki A, Iwasaki H, Aishima S and Noshiro H researched and analyzed data, and wrote, edited and reviewed the manuscript. The manuscript is an original work of all authors. All authors gave final approval for publication. Kai K takes full responsibility for the work as a whole, including the study design, access to data and the decision to submit and publish the manuscript.
Institutional review board statement: This study protocol was reviewed and approved by the Ethics Committee of the Faculty of Medicine at Saga University (approval no. 29-74)
Conflict-of-interest statement: The authors declare that they have no conflicts of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Keita Kai, MD, PhD, Associate Professor, Department of Pathology, Saga University Hospital, 5-1-1 Nabeshima, Saga City, Saga 849-8501, Japan. kaikeit@cc.saga-u.ac.jp
Telephone: +81-952-343264 Fax: +81-952-342055
Received: November 25, 2018
Peer-review started: November 26, 2018
First decision: December 15, 2018
Revised: December 24, 2018
Accepted: December 29, 2018
Article in press: December 30, 2018
Published online: February 26, 2019
Processing time: 93 Days and 19.1 Hours
Abstract
BACKGROUND

The needs for human epidermal growth factor receptor 2 (HER-2) and/or programmed death-ligand 1 (PD-L1) evaluations in gastric cancer are dramatically increasing. Although the importance of standardization of sample fixation has been widely recognized, most of the evidence regarding the fixation duration or type of fixing solution are based on breast cancer.

AIM

To investigate the real effects of fixation conditions on HER-2 testing or PD-L1 testing for gastric cancer using gastrectomy specimens.

METHODS

Thirty-two patients who underwent gastrectomy for gastric cancer were enrolled. Their resected specimens were each divided into four pieces and fixed in four strictly controlled different durations (6 h, 24 h, and 48 h, and 1 wk) by 10% formalin (n = 22) or 10% neutral buffered formalin (NBF) (n = 10). Immunohistochemistry (IHC) of HER-2 and PD-1 was performed, and a pathology examination was conducted. In the HER-2-immunoreactive cases, all four specimens were subjected to dual-color in situ hybridization (DISH). Five cases were assessed as HER-2-positive by IHC and DISH. We used the cut-off values of 1%, 10%, and 50% to assess the IHC findings of PD-L1.

RESULTS

No significant difference was observed in comparisons between the shorter fixation period groups (6 h, 24 h, and 48 h) and the prolonged fixation period (1 wk) group in the HER-2 and PD-L1 analyses. Although no significant difference was observed between 10% formalin and 10% NBF within 1 wk of fixation, the superiority of 10% NBF was confirmed in a long-term (> 3 mo) fixation in both the HER-2 and PD-L1 analyses.

CONCLUSION

In this small-numbered pilot study, prolonged fixation within 1 wk showed no inferiority in HER-2 or PD-L1 testing. However, a large-numbered prospective study is needed to obtain conclusive results.

Keywords: Gastric cancer; Programmed death-ligand 1; Human epidermal growth factor receptor 2; Neutral buffered formalin; Fixation time

Core tip: We prospectively investigated the real effects of fixation conditions on human epidermal growth factor receptor 2 (HER-2) or programmed death-ligand 1 (PD-L1) testing for gastric cancer using 32 cases of gastrectomy specimens. We analyzed these resected specimens dividing into four pieces and fixed in four strictly controlled different durations (6 h, 24 h, and 48 h, and 1 wk) by 10% formalin or 10% neutral buffered formalin. In this small-numbered pilot study, the prolonged fixation within 1 wk showed no inferiority in HER-2 or PD-L1 testing. These results will provide supporting information for the interpretation of HER-2 and PD-L1 testing for prolonged fixation cases due to unavoidable circumstances.