Moderately hypofractionated radiotherapy for localized prostate cancer. Long-term outcome using IMRT and volumetric IGRT

To evaluate long-term outcome after dose-escalated, moderately hypofractionated radiotherapy for prostate cancer. Since 2005, 150 consecutive patients were treated with primary radiotherapy for localized prostate cancer. Intensity modulated radiotherapy (IMRT) using the simultaneous integrated boost (SIB) technique was practiced in all patients and doses of 73.9 Gy (n = 41) and 76.2 Gy (n = 109) were delivered in 32 and 33 fractions, respectively. The pelvic lymph nodes were treated in 41 high-risk patients. Treatment was delivered using cone-beam CT based image-guided radiotherapy (IGRT). Toxicity was assessed prospectively using CTCAE 3.0; biochemical failure was defined according to the Phoenix definition of nadir + 2 ng/ml. Median follow-up of living patients was 50 months. Gastrointestinal (GI) toxicity was mild with > 80 % of the patients free from any GI toxicity during follow-up and no time trend to increased rates or to higher grade of GI toxicity. Two patients suffered from late grade 3 GI toxicity. Acute genitourinary (GU) toxicity grade 1-2 was observed in 85 % of the patients; most patients recovered quickly within 6 weeks after treatment. The rate of GU toxicity grade ≥ 2 was < 10 % at 6-12 month but increased continuously to 22.4 % at 60 months; grade 3 GU toxicity remained below 5 % during follow-up. The 5-year freedom from biochemical failure (FFBF) was 82 % for all patients and 88, 80, and 78 % for low-, intermediate-, and high-risk disease. Favorable FFBF with simultaneously low rates of toxicity was observed after moderately hypofractionated radiotherapy with 2 Gy-equivalent doses ≥ 80 Gy. Conformal IMRT planning and accurate IGRT treatment delivery may have contributed to these results. (orig.)