Definitive, intensity modulated tomotherapy with a simultaneous integrated boost for prostate cancer patients - Long term data on toxicity and biochemical control.

Aim To report long-term data regarding biochemical control and late toxicity of simultaneous integrated boost intensity modulated radiotherapy (SIB-IMRT) with tomotherapy in patients with localized prostate cancer. Background Dose escalation improves cancer control after curative intended radiation therapy (RT) to patients with localized prostate cancer, without increasing toxicity, if IMRT is used. Materials and methods In this retrospective analysis, we evaluated long-term toxicity and biochemical control of the first 40 patients with intermediate risk prostate cancer receiving SIB-IMRT. Primary target volume (PTV) 1 including the prostate and proximal third of the seminal vesicles with safety margins was treated with 70 Gy in 35 fractions. PTV 2 containing the prostate with smaller safety margins was treated as SIB to a total dose of 76 Gy with 2.17 Gy per fraction. Toxicity was evaluated using an adapted CTCAE-Score (Version 3). Results Median follow-up of living patients was 66 (20-78) months. No late genitourinary toxicity higher than grade 2 has been reported. Grade 2 genitourinary toxicity rates decreased from 58% at the end of the treatment to 10% at 60 months. Late gastrointestinal (GI) toxicity was also moderate, though the prescribed PTV Dose of 76 Gy was accepted at the anterior rectal wall. 74% of patients reported any GI toxicity during follow up and no toxicity rates higher than grade 2 were observed. Grade 2 side effects were reported by 13% of the patients at 60 months. 5-year freedom from biochemical failure was 95% at our last follow up. Conclusion SIB-IMRT using daily MV-CT guidance showed excellent long-term biochemical control and low toxicity rates.