Pretreatment Plasma Osteopontin Level As a Marker of Response to Curative Radiotherapy and Hormonal Treatment for Prostate Cancer

Background and purpose Osteopontin is a known marker for tumour hypoxia with relevance for the outcome of radiotherapy. We analysed the plasma concentration of OPN in prostate cancer patients receiving RT with or without ADT to evaluate OPN as a potential marker of treatment response. Materials and methods Between 2012 and 2014, 274 patients with prostate cancer qualifying for RT were enrolled to the study. SCADT received 34.3 % of patients, LCADT 46.3 %. The median OPN concentration was 83.9 ng/mL. We analysed the groups by OPN level: group A with OPN below and group B with OPN above the median. Results There was a significant difference in OPN between the Gleason score (p = 0.005), the D’Amico risk (p = 0.002), the ADT (p < 0.001) and the RT (p = 0.019) groups. We found a positive correlation between OPN and clinical stage (p = 0.042).There were no significant effect of OPN on bRFS, RFS and MFS. The 10-year OS rate for group A was 81 % and for group B 60 % (p < 0.001). Cox analysis showed that low OPN level (p < 0.001), low age (p = 0.002) and low Gleason score (p = 0.038) were associated with higher OS. The prognostic influence of OPN on survival decreased with duration of ADT with the strongest effect of OPN (HR=3.93) observed when RT alone was used, weakest effect (HR=2.48) for SCADT and the smallest effect (HR=2.09) for LCADT. Conclusions Based on the obtained results, we assume that the level of OPN measured before the start of radiotherapy may be an independent predictor of OS of patients with prostate cancer treated with radiotherapy with and without ADT.