Pyruvate kinase type tumor M2 in urological malignancies

Introduction: The dimeric form of pyruvate kinase type M2 is overexpressed in tumor cells (TuM2-PK). The aim of the present study was to evaluate the clinical value of TuM2-PK as a tumor marker for renal cell carcinoma (RCC), transitional cell carcinoma of the bladder (TCC) and prostate cancer (PCA) by using a commercially available enzyme-linked immunosorbent assay for detection of TuM2-PK in plasma. Material and Methods: The TuM2-PK concentration in EDTA plasma was determined quantitatively and immunologically using an ELISA (ScheBo®Tech, Germany). We measured the TuM2-PK plasma levels of 83 patients with RCC, 30 patients with TCC and 30 patients with PCA before any therapy. 100 patients with various non-malignant urological disorders were recruited as the control group. Results: Only patients with RCC showed significantly elevated plasma levels of TuM2-PK compared to the control group (p < 0.01). We found a sensitivity of 42.6% and a specificity of 80.4% using a cut-off value of 15 U/ml (manufacturer’s recommendation). During follow-up, only 50% showed increasing plasma levels of TuM2-PK in case of metastases. Significant differences could not be detected in either TCC or PCA. Conclusions: Our data suggest that TuM2-PK is not a useful marker for TCC and PCA. Due to low sensitivity and specificity, TuM2-PK is not suitable for the diagnosis of RCC. Whether TuM2-PK may be useful in advanced RCC to control success of palliative treatment regimens is still unclear.