T Kubota, T Kaneuji, T Ishizuka, K Kai, Y Yamashita, Y Hishikawa
Cancer-associated fibroblasts (CAFs) influence the tumour microenvironment and promote tumour growth and metastasis. In recent years, the extracellular volume (ECV) fraction derived from contrast-enhanced computed tomography (CECT) has been recognized as a useful, non-invasive imaging biomarker for assessing tissue fibrosis. The aim of this study was to evaluate the clinical significance of the ECV fraction in tongue squamous cell carcinoma (TSCC) by examining its association with histopathological fibrosis. This retrospective observational cohort study analysed 63 patients with TSCC diagnosed between 2015 and 2023. CAFs and tumour microenvironment activity were assessed immunohistochemically using α-SMA, FAP, and TGF-β1. Associations among ECV fraction, fibrosis, and clinical factors were examined. ECV fraction was significantly associated with tumour size, cervical lymph node metastasis, and depth of invasion (all P < 0.001). Receiver operating characteristic curve analysis identified an optimal ECV fraction cut-off of 19.2% for predicting cervical lymph node metastasis. Kaplan-Meier analysis using this cut-off showed that a high ECV fraction was associated with significantly poorer overall survival (P = 0.032). Kaplan-Meier analysis showed that patients with a high ECV fraction experienced significantly poorer overall survival (P = 0.032). Subgroup analysis of early-stage tumours (T1/T2) demonstrated a comparable prognostic value (cut-off = 19.3%), showing a similar prognostic trend. The ECV fraction is a non-invasive imaging biomarker that reflects stromal fibrosis and is associated with tumour progression and cervical lymph node metastasis in TSCC. The ECV fraction cut-off value served as a reliable prognostic indicator, including in early-stage cases. The integration of ECV fraction with the evaluation of histological fibrosis and CAFs may facilitate personalized risk assessment and guide clinical decisions such as elective neck dissection.