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.
Keywords: Fractionation; Late toxicity; Long term follow up; Prostate Cancer; Rectal toxicity; Tomotherapy.