Retrospective Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Endosc. May 16, 2022; 14(5): 320-334
Published online May 16, 2022. doi: 10.4253/wjge.v14.i5.320
Why is endosonography insufficient for residual diagnosis after neoadjuvant therapy for esophageal cancer? Solutions using muscle layer evaluation
Shohei Yonemoto, Masaya Uesato, Akira Nakano, Kentaro Murakami, Takeshi Toyozumi, Tetsuro Maruyama, Hiroshi Suito, Tomohide Tamachi, Manami Kato, Shunsuke Kainuma, Keisuke Matsusaka, Hisahiro Matsubara
Shohei Yonemoto, Masaya Uesato, Akira Nakano, Kentaro Murakami, Takeshi Toyozumi, Tetsuro Maruyama, Hiroshi Suito, Tomohide Tamachi, Manami Kato, Shunsuke Kainuma, Keisuke Matsusaka, Hisahiro Matsubara, Frontier Surgery, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan
Author contributions: Yonemoto S performed the research and wrote the paper; Uesato M came up with the study idea and supervised the study; Uesato M, Nakano A, Murakami K, Toyozumi T, Maruyama T, Suito H, Tamachi T, Kobayashi M and Kainuma S collected the data; Matsusaka K provided pathological advice; Matsubara H supervised the report.
Institutional review board statement: The study protocol was approved by Hospital of Chiba University Biomedical Research Ethics Committee, No. 3550.
Informed consent statement: Written informed consent was obtained before treatment for all patients.
Conflict-of-interest statement: All authors declare no conflicts-of-interest related to this article.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (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: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Masaya Uesato, MD, PhD, Assistant Professor, Doctor, Statistician, Surgeon, Frontier Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. uesato@faculty.chiba-u.jp
Received: December 4, 2021
Peer-review started: December 4, 2021
First decision: January 8, 2022
Revised: February 11, 2022
Accepted: April 3, 2022
Article in press: April 3, 2022
Published online: May 16, 2022
Processing time: 162 Days and 23.8 Hours
Abstract
BACKGROUND

The diagnosis of residual tumors using endoscopic ultrasound (EUS) after neoadjuvant therapy for esophageal cancer is considered challenging. However, the reasons for this difficulty are not well understood.

AIM

To investigate the ultrasound imaging features of residual tumors and identify the limitations and potential of EUS.

METHODS

This exploratory prospective observational study enrolled 23 esophageal squamous cell carcinoma patients receiving esophagectomy after neoadjuvant therapy [15 patients after neoadjuvant chemotherapy (NAC) and 8 patients after chemoradiotherapy (CRT)] at the Department of Surgery, Chiba University Hospital, between May 2020 and October 2021. We diagnosed the T stage for specimens using ultrasound just after surgery and compared ultrasound images with the cut surface of the fixed specimens of the same level of residual tumor. The ratio of esophageal muscle layer defect measured by ultrasound was compared with clinicopathological factors. Furthermore, the rate of reduction for the muscle layer defect was evaluated using EUS images obtained before and after neoadjuvant therapy.

RESULTS

The accuracy of T stage rate was 61% (n = 14/23), which worsened after CRT (38%, n = 3/8) than after NAC (73%, n = 11/15) because of overstaging. Moreover, pT0 could not be diagnosed in all cases. The detection rate of residual tumor for specimens using ultrasound retrospectively was 75% (n = 15/20). There was no correlation between after-NAC (79%, n = 11/14) and after-CRT (67%, n = 4/6) detection rate. The detection of superficial and submucosal types was poor. The pathologic tumor size and pathological response were correlated. Tumor borders were irregular and echogenicity was mixed type after CRT. There was a correlation between the pT stage (pT0/1 vs pT2/3) and the length of muscle layer circumference (P = 0.025), the length of muscle layer defect (P < 0.001), and the ratio of muscle layer defect (P < 0.001). There was also a correlation between the pT stage and the rate of muscle layer defect reduction measured by EUS (P = 0.001).

CONCLUSION

Compared to pathological images, some tumors are undetectable by ultrasound. Focusing on the esophageal muscle layer might help diagnose the depth of the residual tumor.

Keywords: Esophageal cancer; Esophageal squamous cell carcinoma; Neoadjuvant therapy; Endoscopic ultrasound; Residual tumor; Endosonography

Core Tip: This exploratory prospective observational study evaluated the effectiveness of endoscopic ultrasound (EUS) in diagnosing residual tumors after neoadjuvant therapy for esophageal squamous cell carcinoma. It is well known that the diagnosis using EUS after neoadjuvant therapy is inaccurate. The results of ultrasound for surgical specimens are not satisfactory as well. Our study found that the inability to distinguish scar tissue from the tumor made detection and diagnosis impossible in some residual tumors. Esophageal muscle layer defect as an indirect finding correlated with the depth of the residual tumor. These insights could help improve the diagnosis of residual tumors.