Volumetric image-guided highly conformal radiotherapy of the prostate bed: Toxicity analysis

Publication date: January–February 2017
Source:Reports of Practical Oncology & Radiotherapy, Volume 22, Issue 1
Author(s): Gianluca Ingrosso, Alessandra Carosi, Daniela di Cristino, Elisabetta Ponti, Andrea Lancia, Alessandra Murgia, Claudia Bruni, Pasquale Morelli, Franca Pietrasanta, Riccardo Santoni
AimTo evaluate toxicity of high conformal image-guided radiotherapy of the prostate bed.BackgroundRadiotherapy of the prostate bed has a pivotal role in the post-operative and salvage settings, but few clinical data are available on the use of daily image guidance in combination with highly conformal techniques, and data on long-term results are lacking.Materials and methodsWe analyzed 118 patients irradiated on the prostate bed using conformal plans processed with a micro-multileaf collimator, and daily checking treatment set-up with a cone-beam CT system. Correlation between toxicity and clinical-dosimetric parameters was assessed by the Cox regression model and log-rank test. Survival analyses were performed with the Kaplan–Meier method.ResultsMedian follow-up was 54.08 months. Late grade ≥2 gastro-intestinal (GI) and genito-urinary (GU) toxicity were 3.4% and 4.2%, respectively. Actuarial 4-year late grade ≥2 GI and GU toxicities were 4% and 6%, respectively. Four-year relapse-free survival was 87%. At log-rank test, acute grade ≥2 GI toxicity is associated with the use of antihypertensives (p=0.03), and there is a trend toward significance between the use of anticoagulants and late grade ≥2 GI toxicity (p=0.07). At Cox analysis, acute grade ≥2 GU toxicity is correlated with the percentage of bladder volume receiving more than 65Gy (p=0.02, HR 1.87 CI 1.25–2.8), and the maximal dose to the rectum is correlated to the development of late grade ≥2 GI toxicity (p=0.03, HR 2.75 CI 1.10–6.9).ConclusionsConformal volumetric image-guided radiotherapy of the prostate bed leads to low toxicity rates.



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