Krishnan A. Rethinking carcinoembryonic antigen and carbohydrate antigen 19-9 in gastric cancer surveillance: From statistical association to clinical utility. World J Gastrointest Oncol 2026; 18(10): 119774 [DOI: 10.4251/wjgo.119774]
Corresponding Author of This Article
Arunkumar Krishnan, Department of Supportive Oncology, Atrium Health Levine Cancer, Atrium Health Wake Forest Baptist Comprehensive Cancer Center, 1021 Morehead Medical Dr, Charlotte, NC 28204, United States. dr.arunkumar.krishnan@gmail.com
Research Domain of This Article
Oncology
Article-Type of This Article
review-article
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Krishnan A. Rethinking carcinoembryonic antigen and carbohydrate antigen 19-9 in gastric cancer surveillance: From statistical association to clinical utility. World J Gastrointest Oncol 2026; 18(10): 119774 [DOI: 10.4251/wjgo.119774]
World J Gastrointest Oncol. Oct 15, 2026; 18(10): 119774 Published online Oct 15, 2026. doi: 10.4251/wjgo.119774
Rethinking carcinoembryonic antigen and carbohydrate antigen 19-9 in gastric cancer surveillance: From statistical association to clinical utility
Arunkumar Krishnan
Arunkumar Krishnan, Department of Supportive Oncology, Atrium Health Levine Cancer, Atrium Health Wake Forest Baptist Comprehensive Cancer Center, Charlotte, NC 28204, United States
Author contributions: Krishnan A conceptualized the manuscript and conducted the assessment; Krishnan A prepared the manuscript draft, which was subsequently reviewed and approved for final publication.
AI contribution statement: AI-based tools were used in this manuscript for language refinement and editorial polishing - improving grammar and readability - consistent with most current publisher policies on AI-assisted language editing. No AI tool was used to generate the substantive analysis, conclusions, or scientific arguments or writing.
Conflict-of-interest statement: The author reports no relevant conflicts of interest for this article.
Corresponding author: Arunkumar Krishnan, Department of Supportive Oncology, Atrium Health Levine Cancer, Atrium Health Wake Forest Baptist Comprehensive Cancer Center, 1021 Morehead Medical Dr, Charlotte, NC 28204, United States. dr.arunkumar.krishnan@gmail.com
Received: February 5, 2026 Revised: February 23, 2026 Accepted: March 9, 2026 Published online: October 15, 2026 Processing time: 223 Days and 12.6 Hours
Core Tip
Core Tip: This opinion review critically examines a recent study linking carcinoembryonic antigen and carbohydrate antigen 19-9 to gastric cancer recurrence and chemotherapy toxicity, identifying fundamental methodological gaps that limit clinical applicability. The concerns raised-selection bias, reverse causality, inadequate confounding control, mishandled survival analysis, and absent predictive performance assessment-are not unique to one study; they represent recurring weaknesses across the biomarker literature in gastrointestinal oncology. We argue that the field must embrace modern biostatistical frameworks, integrate molecular subtyping and liquid biopsy technologies, and adopt rigorous validation standards before any single biomarker can reliably guide postoperative management.
