Tumor mitochondrial respiration rather than glycolytic activity predicts recurrence in colorectal cancer: an ex vivo bioenergetic profiling study

BACKGROUND: Metabolic reprogramming is a recognized hallmark of colorectal cancer (CRC), yet whether intratumoral bioenergetic capacity directly influences clinical outcomes remains unclear. In particular, the relative prognostic contributions of mitochondrial respiration and glycolytic activity to postoperative recurrence have not been systematically evaluated. This study aimed to determine whether tumor oxygen consumption rate (OCR) or extracellular acidification rate (ECAR), measured ex vivo by Seahorse bioenergetic assays, is associated with recurrence-free survival (RFS) and overall survival (OS) in patients with resected CRC. METHODS: In a single-center prospective cohort of 104 patients who underwent surgical resection for CRC between 2012 and 2017, paired tumor and adjacent normal mucosal specimens were analyzed using the Seahorse XF24 analyzer to quantify basal OCR and ECAR. Tumors were stratified by cohort median values and by receiver operating characteristic (ROC)-derived cutoffs optimized for recurrence prediction. Associations with RFS and OS were assessed using Kaplan-Meier analysis and Cox proportional hazards regression, adjusting for clinicopathological covariates. RESULTS: Over a median follow-up of 69 months, tumor OCR was significantly lower than that of adjacent normal mucosa (p < 0.001), whereas ECAR did not differ between paired tissues. OCR and ECAR were positively correlated within tumors (R² = 0.268, p < 0.001). In multivariate Cox regression, higher tumor OCR was independently associated with shorter RFS, both as a continuous variable (hazard ratio 1.455 per 1000-unit increase, p = 0.010) and when dichotomized by median or ROC-derived cutoffs (all p < 0.05). ROC analysis demonstrated moderate discriminatory ability for OCR (area under the curve 0.650), whereas ECAR showed no prognostic value. No bioenergetic parameter was significantly associated with OS. CONCLUSIONS: Intratumoral mitochondrial respiratory capacity, rather than glycolytic activity, independently predicts recurrence in resected CRC. These findings suggest that tumor OCR may serve as a functional metabolic biomarker for recurrence risk stratification, warranting prospective validation in independent cohorts.