Evaluation of the relationship of erythrocyte membrane Na+/K+-ATPase enzyme activity and tumor response to chemoradiotherapy in patients diagnosed with locally advanced nonsmall cell lung cancer and glioblastoma multiforme.

Context: Radiotherapy is the commonly used therapeutic modality for inoperable cancer types. We investigated chemoradiotherapy (CRT) effects on the Na+/K+-ATPase enzyme. Aims: The aim of the present study was to determine the usefulness of Na+/K+-ATPase enzyme as a prognostic factor and as a potential target for increasing the CRT response of nonsmall cell lung cancer (NSCLC) and glioblastoma multiforme (GBM). Settings and Design: We prospectively evaluated 30 patients (all were treated with CRT) and 20 healthy controls. Subjects and Methods: Blood samples were taken before and after the completion of CRT from the patients and once from the control group. Erythrocyte membranes were isolated and Na+/K+-ATPase enzyme activities were measured. Statistical Analysis Used: The statistical significance was calculated using the one-way analysis of variance test and the Tukey's test. Results: Na+/K+-ATPase activity levels were increased in the patient groups before completion of CRT CRT, when compared to the control group. A significant decrease in Na+/K+-ATPase activity was noted in the patient groups after the completion of CRT when compared to before CRT, but the activity remained higher than in the control group. No relationship was noted between survival and Na+/K+-ATPase activity in NSCLC and GBM patients. Conclusion: Levels of Na+/K+-ATPase activity were initially high in patients with NSCLC and GBM, and decreased after the completion of CRT. This supports a linkage between the altered activity of Na+/K+-ATPase and the treatment effects of CRT. The observed change in Na+/K+-ATPase activity in cancer patients receiving CRT suggests that targeting this enzyme could represent a novel mean of combatting NSCLC and GBM.