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World J Gastroenterol. Feb 28, 2024; 30(8): 794-798
Published online Feb 28, 2024. doi: 10.3748/wjg.v30.i8.794
Immune signature of small bowel adenocarcinoma and the role of tumor microenvironment
Grigorios Christodoulidis, Marina Nektaria Kouliou, Konstantinos Eleftherios Koumarelas
Grigorios Christodoulidis, Marina Nektaria Kouliou, Konstantinos Eleftherios Koumarelas, Department of General Surgery, University Hospital of Larissa, Larissa 41110, Greece
Author contributions: Christodoulidis G, Kouliou MN and Koumarelas KE contributed to this paper; Christodoulidis G designed the overall concept and outline of the manuscript; Christodoulidis G, Kouliou MN and Koumarelas KE contributed to the discussion and design of the manuscript; Christodoulidis G, Koumarelas KE and Kouliou MN contributed to the writing, editing the manuscript, and review of literature.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
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: Grigorios Christodoulidis, PhD, Doctor, Editor-in-Chief, Department of General Surgery, University Hospital of Larissa, Mezourlo, Larissa 41110, Greece. gregsurg09@gmail.com
Received: November 23, 2023
Peer-review started: November 23, 2023
First decision: January 5, 2024
Revised: January 13, 2024
Accepted: January 30, 2024
Article in press: January 30, 2024
Published online: February 28, 2024

In this editorial we comment on the article published “Clinical significance of programmed cell death-ligand expression in small bowel adenocarcinoma is determined by the tumor microenvironment”. Small bowel adenocarcinoma (SBA) is a rare gastrointestinal neoplasm and despite the small intestine's significant surface area, SBA accounts for less than 3% of such tumors. Early detection is challenging and the reason arises from its asymptomatic nature, often leading to late-stage discovery and poor prognosis. Treatment involves platinum-based chemotherapy with a 5-fluorouracil combination, but the lack of effective chemotherapy contributes to a generally poor prognosis. SBAs are linked to genetic disorders and risk factors, including chronic inflammatory conditions. The unique characteristics of the small bowel, such as rapid cell renewal and an active immune system, contributes to the rarity of these tumors as well as the high intratumoral infiltration of immune cells is associated with a favorable prognosis. Programmed cell death-ligand 1 (PD-L1) expression varies across different cancers, with potential discrepancies in its prognostic value. Microsatellite instability (MSI) in SBA is associated with a high tumor mutational burden, affecting the prognosis and response to immunotherapy. The presence of PD-L1 and programmed cell death 1, along with tumor-infiltrating lymphocytes, plays a crucial role in the complex microenvironment of SBA and contributes to a more favorable prognosis, especially in the context of high MSI tumors. Stromal tumor-infiltrating lymphocytes are identified as independent prognostic indicators and the association between MSI status and a favorable prognosis, emphasizes the importance of evaluating the immune status of tumors for treatment decisions.

Keywords: Programmed cell death 1, Programmed cell death-ligand 1, Programmed death ligand, Small bowel adenocarcinoma, Tumor infiltrating lymphocytes, Tumor microenvironment, Microsatellite instability

Core Tip: Small bowel adenocarcinoma (SBA) is an uncommon gastrointestinal tumor, accounting for fewer than 3% of all cases, even though it constitutes 95% of the gastrointestinal tract. SBA, which is mostly located in the duodenum, typically goes undetected for a long period of time, resulting to a late-stage discovery and a dismal prognosis. The immunological response, consisting of CD4+ and CD8+ T-lymphocytes, is critical in determining the prognosis. Programmed cell death 1/programmed cell death-ligand 1 (PD-L1) pathway, which is known to be involved in immune evasion in cancer, is implicated in SBA, with PD-L1 expression to a variety of prognostic consequences. The complicated interaction of immunological components, including as TILs and regulatory T cells, emphasizes the complexities of SBA.