{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,17]],"date-time":"2026-10-17T18:52:10Z","timestamp":1792263130596,"version":"4.4.0"},"reference-count":43,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2026,5,25]],"date-time":"2026-05-25T00:00:00Z","timestamp":1779667200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Sarcopenia is increasingly invoked as a determinant of treatment-related toxicity, perioperative morbidity, treatment intolerance, and survival in oncology; however, contemporary international consensus frameworks define sarcopenia as a multidimensional neuromuscular syndrome centered on impaired muscle strength, physical performance, and muscle quality, whereas most oncologic studies operationalize sarcopenia using computed tomography (CT)-derived skeletal muscle mass alone. In this context, muscle quantity is effectively employed as a diagnostic surrogate for a function-centered syndrome. CT-defined skeletal muscle depletion\u2014more precisely described as myopenia\u2014remains a reproducible and clinically informative structural biomarker, yet defining sarcopenia by muscle mass alone aggregates biologically heterogeneous phenotypes, including neuromuscular dysfunction, inflammation-driven cachexia, and substrate-related malnutrition. Such surrogate-based definitions contribute to variable prevalence estimates, inconsistent prognostic associations, and interpretive instability across studies. Clinically, reliance on CT-based muscle mass as a surrogate for sarcopenia may influence chemotherapy dosing, perioperative risk stratification, and supportive care allocation without direct assessment of neuromuscular function; in research settings, mass-based definitions may dilute treatment effects in exercise or nutritional trials and complicate meta-analytic synthesis by conflating structural and functional constructs. This analysis does not question the value of radiologic muscle assessment but argues that CT-derived muscle mass should be recognized as a structural biomarker within a multidimensional framework rather than as a standalone diagnostic surrogate for sarcopenia. A tiered, oncology-adapted approach integrating functional assessment, muscle quality, and relevant metabolic context may enhance risk discrimination, improve trial design, and strengthen translational precision in supportive oncology.<\/jats:p>","DOI":"10.3390\/diagnostics16111611","type":"journal-article","created":{"date-parts":[[2026,5,25]],"date-time":"2026-05-25T11:57:44Z","timestamp":1779710264000},"page":"1611","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Defining Sarcopenia in Oncology by CT-Based Muscle Mass: The Clinical and Research Consequences of a Diagnostic Surrogate"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8120-7123","authenticated-orcid":false,"given":"Erkan","family":"Topkan","sequence":"first","affiliation":[{"name":"Department of Radiation Oncology, Faculty of Medicine, Baskent University, 01120 Adana, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8251-6913","authenticated-orcid":false,"given":"Efsun","family":"Somay","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Baskent University, 06490 Ankara, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Duriye","family":"Ozturk","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, School of Medicine, Afyonkarahisar Health Sciences University, 03030 Afyonkarahisar, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8087-3140","authenticated-orcid":false,"given":"Ugur","family":"Selek","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, School of Medicine, Koc University, 34010 Istanbul, Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"412","DOI":"10.1093\/ageing\/afq034","article-title":"Sarcopenia: European consensus on definition and diagnosis: Report of the European Working Group on Sarcopenia in Older People","volume":"39","author":"Baeyens","year":"2010","journal-title":"Age Ageing"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1093\/ageing\/afy169","article-title":"Sarcopenia: Revised European consensus on definition and diagnosis","volume":"48","author":"Bahat","year":"2019","journal-title":"Age Ageing"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"300","DOI":"10.1016\/j.jamda.2019.12.012","article-title":"Asian Working Group for Sarcopenia 2019: Consensus update on diagnosis and treatment","volume":"21","author":"Chen","year":"2020","journal-title":"J. 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