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Salvage re-irradiation in patients affected by radiorecurrent prostate cancer might be a valid as well as challenging treatment option. The aim of this study was to evaluate feasibility and toxicity of salvage external beam radiotherapy (EBRT) re-treatment in patients affected by radiorecurrent prostate cancer within the prostate gland or the prostate bed. 15 patients underwent EBRT re-treatment using helical tomotherapy (HT), with daily Megavolt computed tomography image-guidance. We registered toxicity according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Biochemical relapse was defined as a PSA increase > 20% compared with the pre-EBRT re-treatment value. Survival curves were calculated using the Kaplan-Meier method. All patients received a total dose of 50 Gy (25 × 2 Gy), and 7 (46.6%) had concomitant androgen deprivation therapy (median duration of 12 months). With a median follow-up of 40.9 months, the 2-year and 4-year biochemical relapse-free survival were 55% and 35%, respectively. Acute and late genito-urinary (GU) toxicity ≥2 were recorded in 4 (26.6%) and 5 (33.3%) patients, respectively, and the 4-year late GU toxicity was 30%. Acute gastrointestinal toxicity ≥2 was recorded in 2 (13.3%) cases, whereas no patient experienced late toxicity. Despite the inherent bias of a retrospective analysis, our long-term results showed a low toxicity profile with a relatively low rate of biochemical control for HT re-treatment in patients affected by local radiorecurrent prostate cancer. Prospective trials are needed to investigate the role of EBRT in this setting. [ABSTRACT FROM AUTHOR]

Background Intensity-modulated radiotherapy (IMRT) improves dose distribution in head and neck (HN) radiation therapy. Volumetric-modulated arc therapy (VMAT), a new form of IMRT, delivers radiation in single or multiple arcs, varying dose rates (VDR-VMAT) and gantry speeds, has gained considerable attention. Constant dose rate VMAT (CDR-VMAT) associated with a fixed gantry speed does not require a dedicated linear accelerator like VDR-VMAT. The present study explored the feasibility, efficiency and delivery accuracy of CDR-VMAT, by comparing it with IMRT and VDR-VMAT in treatment planning for HN cancer. Methods and materials Step and shoot IMRT (SS-IMRT), CDR-VMAT and VDR-VMAT plans were created for 15 HN cancer patients and were generated by Pinnacle 3 TPS (v 9.8) using 6 MV photon energy. Three PTVs were defined to receive respectively prescribed doses of 66 Gy, 60 Gy and 54 Gy, in 30 fractions. Organs at risk (OARs) included the mandible, spinal cord, brain stem, parotids, salivary glands, esophagus, larynx and thyroid. SS-IMRT plans were based on 7 co-planar beams at fixed gantry angles. CDR-VMAT and VDR-VMAT plans, generated by the SmartArc module, used a 2-arc technique: one clockwise from 182° to 178° and the other one anti-clockwise from 178° to 182°. Comparison parameters included dose distribution to PTVs ( D mean , D 2% , D 50% , D 95% , D 98% and Homogeneity Index), maximum or mean doses to OARs, specific dose-volume data, the monitor units and treatment delivery times. Results Compared with SS-IMRT, CDR-VMAT significantly reduced the maximum doses to PTV1 and PTV2 and significantly improved all PTV3 parameters, except D 98% and D 95% . It significantly spared parotid and submandibular glands and was associated with a lower D mean to the larynx. Compared with VDR-VMAT, CDR-VMAT was linked to a significantly better D mean , to the PTV3 but results were worse for the parotids, left submandibular gland, esophagus and mandible. Furthermore, the D mean to the larynx was also worse. Compared with SS-IMRT and VDR-VMAT, CDR-VMAT was associated with higher average monitor unit values and significantly shorter average delivery times. Conclusions CDR-VMAT appeared to be a valid option in Radiation Therapy Centers that lack a dedicated linear accelerator for volumetric arc therapy with variable dose-rates and gantry velocities, and are unwilling or unable to sanction major expenditure at present but want to adopt volumetric techniques. [ABSTRACT FROM AUTHOR]