Rectal/urinary toxicity after hypofractionated vs. conventional radiotherapy in high risk prostate cancer: systematic review and meta analysis

R. Di Franco, V. Borzillo, V. Ravo, G. Ametrano, F. Cammarota, S. Rossetti, F.J. Romano, C. D’Aniello, C. Cavaliere, G. Iovane, M.A. Porricelli, M. Muto, M. Berretta, G. Facchini, P. Muto

Progetto ONCONET2.0 – Linea progettuale 14 per l’implementazione della prevenzione e diagnosi precoce del tumore alla prostata e testicolo – Regione Campania, Italy. rosselladifrancort@gmail.com

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• Oncology

OBJECTIVE: The aim of our report was to review the literature concerning the toxicity of radiation therapy in patients treated for high-risk prostate cancer, and to evaluate the differences in toxicity between conventional fractionation and hypofractionated treatments, in view of different techniques used in high-risk prostate cancer patients.

MATERIALS AND METHODS: PubMed database has been explored for studies concerning acute and late urinary/gastrointestinal toxicity in high-risk prostate cancer patients treated with radiotherapy. Prospective studies, concerning potential relationship between acute/late genitourinary (GU)/gastrointestinal (GI) toxicity and prostate radiotherapy in patients with high-risk prostate cancer, were included in the final analysis. Data collected from single arm, phase II non-randomized and randomized studies have been evaluated to perform odds ratio for toxicity risk. Furthermore, meta-analysis randomized prospective trials were considered suitable because they had recruited high-risk prostate cancer patients who didn’t undergo surgery, with available data on ≥ G2 toxicity frequency.

RESULTS: The initial search provided 606 results, but only 35 manuscripts met all eligibility requirements and were included in this report. In order to perform odds ratio we observed a decrease in late gastrointestinal toxicity for patients treated with hypofractionated schemes compared to CV treated ones. Among patients who underwent conventional treatment, SIB seemed to decrease acute genitourinary side effects; SIB-Hypo treated patients suffered less toxicity than patients treated with hypofractionated- sequential boost schemes. Hypo-SIB schemes would seem less toxic in terms of acute gastrointestinal and late genitourinary side effects than CV-SIB. Therefore, our focus shifted to 6 clinical trials evaluating genitourinary and gastrointestinal toxicity in patients who had been randomized to receive conventional fractionation or hypofractionated treatment, in both cases with IMRT technology. Our meta-analysis of these randomized trials involving patients with high-risk prostate cancer showed a statistically significant increase in late genitourinary toxicity for hypo-treated patients; no difference was observed in acute genitourinary/gastrointestinal toxicity, and in late gastrointestinal toxicity.

CONCLUSIONS: Our analysis doesn’t want to establish a definitive truth; very few trials assessed only high risk-class patients. Our purpose is to stimulate further randomized prospective trials focusing both on the effectiveness and toxicity profile (toxicity/effectiveness ratio), taking into account the use of different technologies and doses.

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