After external radiotherapy or brachytherapy, the Prostate Specific Antigen (PSA) value is often fluctuating and PSA nadir may only be reached after 2 years or more and may remain detectable several years after the completion of radiation. Moreover, PSA bounces and blips render patients and physicians very anxious about any possibility of a relapse. In this context, biomarkers that could predict the response to radiation earlier than PSA for patients with prostate cancer appear long overdue.