First, the expression profiles of five key radiation-responsive genes (FDXR, SESN1, GADD45, DDB2, and MDM2) during the course of RT in the blood of 8 prostate cancer patients (Table 1) treated with IMRT (Fig. 2a) and SABR (Fig. 2b) were analyzed. The gene discussed is DDB2; the disease is prostate cancer.