Gastrointestinal (GI) cancer is one of the most common causes of cancer-related deaths worldwide.Tumor markers are valuable in detecting post-surgical recurrence or in monitoring response to chemotherapy.Pyruvate kinase isoform M2 (PKM2),a glycolytic enzyme catalyzing conversion of phosphoenolpyruvate (PEP) to pyruvate,confers a growth advantage to the tumor cells and enables them to adapt to the tumor microenvironment.In this review,we have summarized current research on the expression and regulation of PKM2 in tumor cells,and its potential role in GI carcinogenesis and progression.Furthermore,we have also discussed the potential of PKM2 as a diagnostic and screening marker,and a therapeutic target in GI cancer.