Preliminary outcome on toxicities and biochemical control of image-guided radiotheraPy in intermediateto high-risk Prostate cancer

Purpose: To evaluate the preliminary outcome of curative image-guided radiotherapy (IGRT) with Helical Tomotherapy or RapidArc for patients with intermediate- to highrisk prostate cancer. Materials and Methods: Between April 2008 and October 2012, 72 patients with pathologically proven prostate adenocarcinoma were included. Age ranged from 58 to 89 with mean age of 73 years. Twenty-three patients were intermediate-risk group and 49 were high-risk group. Fifty-one and 21 patients were treated with Helical Tomotherapy and RapidArc respectively. The mean radiation dose was 74 Gy. Twenty patients were treated with external beam radiation therapy alone (EBRT-only group) and 52 were treated with EBRT plus androgen deprivation therapy (EBRT-ADT group). The biochemical failure was defined by a rise of 2 ng/mL or more above the nadir prostate specific antigen (PSA). The nadir was defined as lowest PSA value preceding a given threshold of 0.2 ng/mL or as absolutely lowest PSA before the transient bounce. Toxicities were assessed and documented in agreement with the Common Terminology Criteria for Adverse Events version 3 (CTCAE v.3.0). Results: With the mean follow-up period of 28 months, four patients (5%, 4/72) had biochemical failure. The mean time interval to achieve the nadir PSA (TnPSA) in the EBRT-only group and EBRT-ADT group were 15.58 months and 5.73 months respectively (p = 0.001). All patients tolerated IGRT without any interruption. The patients exhibited grades 1 and 2 levels of acute genitourinary toxicities at 59.7% (43/72) and 5.6% (4/72). Grade 1 acute gastrointestinal toxicity was 34.7% (25/72). As for late toxicity, two patients developed grade 2 radiation proctitis 20 months after EBRT. Conclusion : IGRT for patients with intermediate- to high-risk prostate cancer was an effective and well-tolerated treatment. The EBRT-ADT group had better biochemical control than the EBRT-only group. Longer follow-up period was necessary.