The lack of evidence for correlation of pyruvate kinase M2 expression with tumor grade in non-small cell lung cancer.

Background: Over the last years, evidence has accumulated that an increased expression of pyruvate kinase M2 isozyme (PKM2) is related to neoplastic transformation as well that its plasma concentrations might be a marker of lung cancer progression. Materials and Methods: In the present manuscript an immunohistochemical technique was used to detect the expression of two pyruvate kinase isoforms: PKM1 (muscle isozyme of PK) and PKM2 as well Ki-67 antigen on paraffin sections of 218 cases of non-small cell lung cancer (NSCLC) of different histological types and grades of malignancy. Results: A significant correlation between expressions of both pyruvate kinase isoforms in all NSCLC types was found (r=0.42, p<0.0001). Expression levels of PKM1 and PKM2 were independent of the histological classification of the tumor and patients' clinicopathological data. Conclusions: PKM2 and PKM1 have no value as predictive markers of NSCLC regardless of the histological type and grade of malignancy.