Isoprostane levels in the urine of patients with prostate cancer receiving radiotherapy are not elevated

PURPOSE: Previous studies have demonstrated that urinary 8-iso-prostaglandin F (PGF)2alpha serves as a powerful biomarker of lipid peroxidation in diseases in which oxidative stress plays an important role in its pathophysiology. The goal of this study was to measure the urinary isoprostane levels in patients with prostate cancer treated with radiotherapy (RT) in an effort to determine whether isoprostane levels are elevated compared with in historical controls, whether the levels increase after RT, and whether such an increase would correlate positively with the degree of GU symptoms during treatment. METHODS AND MATERIALS: Urine samples were obtained before and during RT from patients enrolled on a recently reported Phase III trial examining the therapeutic efficacy of ibuprofen in decreasing the acute urinary symptoms of RT. Radioimmunoassays were performed on urine samples for 8-iso-PGF2alpha or 15-keto-dihydro-PGF2alpha. RESULTS: Fifteen patients provided samples both before and during RT. The levels of 8-iso-PGF(2alpha) and 15-keto-dihydro-PGF2alpha in the urine samples obtained before prostate RT (0.27 and 0.41 nmol/mmol creatinine) did not differ appreciably from the values observed in a normal cohort (0.27 and 0.46 nmol/mmol creatinine) and did not change after RT (0.23 and 0.37 nmol/mmol creatinine). CONCLUSION: We were unable to detect an increase in either 8-iso-PGF2alpha or 15-keto-dihydro-PGF2alpha in the urine of patients with prostate cancer compared with in historical normal controls. We were also unable to measure an increase in either of the eicosanoids during RT to the prostate gland.