PDK4 and cancer: Contrasting with previous studies focusing on genomic alterations and pathological behaviors of cancer cells, we herein propose that routine surveillance of lactate, a major metabolic product derived from PDK4-driven glycolysis in stromal cells upon TIS, via a noninvasive avenue such as liquid biopsy, provides a new, practical and accurate strategy for appraisal of advanced pathologies in clinical oncology (Fig. 6i).