Purpose: To evaluate and compare plasma osteopontin (OPN, a candidate prostate cancer biomarker) levels in prostate cancer patients receiving radiotherapy or combined radiotherapy or hormone therapy.
Methods: OPN levels were determined by ELISA in 40 prostate cancer patients eligible for radiotherapy (n=18 radiotherapy alone, n=22 combined radiotherapy and hormone therapy) before the start of irradiation, during treatment, and one month after its completion.
Results: OPN levels were significantly higher (p=0.02) in prostate cancer patients after receiving radiotherapy compared to baseline. In a subgroup analysis, there were no differences in OPN levels before and after treatment in patients undergoing radiotherapy alone, but OPN levels were significantly higher in patients after radiotherapy with hormone therapy compared to baseline (p=0.04) and in patients during radiotherapy compared to baseline (p=0.03).
Conclusions: Radiotherapy can increase plasma OPN concentrations in patients with prostate cancer, and radiotherapy may interact with hormone therapy to increase OPN concentrations. These differences suggest that OPN is worthy of further study as a predictive biomarker.