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Background: Postmastectomy radiotherapy (PMRT) with TomoHelicalTM (TH) or TomoDirectTM (TD) allows a uniform target coverage. In this study, we compare treatment plans using TD and TH in the setting of hypofractionated PMRT and immediate breast reconstruction. Material and methods: The TD-treatment plans of breast cancer patients treated between May 2016 and August 2019 were retrospectively selected. All the TD plans were re-planned on TH with the same prescription dose (40.05 Gy/15 fractions) and according to our dose/volume constraints. Data about the 2 treatment plans were compared with a focus on PTV coverage and all the organs at risk (OARs) constraints. Results: Fifty patients for a total number of 100 treatment plans (50 with TD and 50 re-planned with TH) were analyzed. All the median value in the TD PTV CHEST WALL plans fulfilled the predefined planning objectives, even though TH emerged as best for target coverage with statistically significant difference for V90%. TD provided the lowest V95% for the PTV SVC, but the median value was near to the recommended value of 90% (89.8 % vs 98.6% for TD and TH, respectively). Overall, TD reached the best OARs sparing. The main statistically significant differences with TH were for contralateral breast, ipsilateral and contralateral lung. All the other dose values for TH were higher than TD, but they fulfilled the recommended/acceptable predefined planning objectives. Conclusions: In the setting of PMRT, TD compared to TH reached an acceptable target volume coverage, with an optimal sparing of OARs.

Aim: The primary aim of this study is to provide preliminary indications for safe constraints of rectum and bladder in patients re-irradiated with stereotactic body RT (SBRT). Methods: Data from patients treated for prostate cancer (PCa) and intraprostatic relapse, from 1998 to 2016, were retrospectively collected. First RT course was delivered with 3D conformal RT techniques, SBRT or volumetric modulated arc therapy (VMAT). All patients underwent re-irradiation with SBRT with heavy hypofractionated schedules. Cumulative dose-volume values to organs at risk (OARs) were computed and possible correlation with developed toxicities was investigated. Results: Twenty-six patients were included. Median age at re-irradiation was 75 years, mean interval between the two RT courses was 5.6 years and the median follow-up was 47.7 months (13.4–114.3 months). After re-irradiation, acute and late G ≥ 2 GU toxicity events were reported in 3 (12%) and 10 (38%) patients, respectively, while late G ≥ 2 GI events were reported in 4 (15%) patients. No acute G ≥ 2 GI side effects were registered. Patients receiving an equivalent uniform dose of the two RT treatments < 131 Gy appeared to be at higher risk of progression (4-yr b-PFS: 19% vs 33%, p = 0.145). Cumulative re-irradiation constraints that appear to be safe are D30% < 57.9 Gy for bladder and D30% < 66.0 Gy, D60% < 38.0 Gy and V122.1 Gy < 5% for rectum. Conclusion: Preliminary re-irradiation constraints for bladder and rectum have been reported. Our preliminary investigation may serve to clear some grey areas of PCa re-irradiation.

Background: Hypofractionated proton beam radiotherapy (PBT) is gaining attention in early-stage non-small cell lung cancer (ES-NSCLC). However, there is a large unmet need to define indications, prescription doses and potential adverse events of protons in this clinical scenario. Hence, the present work aims to provide a critical literature revision, and to investigate associations between fractionation schedules/ biological effective doses (BEDs), oncological outcomes and toxicities.Materials and methods: This systematic review and meta-analysis complied with the PRISMA recommendations. Inclusion criteria were: 1) curative-intent hypofractionated PBT for ES-NSCLC (>= 3 Gy(RBE)/fraction), 2) report of the clinical outcomes of interest, 3) availability of full-text written in English. The bibliographic search was performed on the NCBI Pubmed, Embase and Scopus in September 2021; no other limitations were applied. The BED was calculated for each included study (alpha/beta = 10 Gy); the median BED for all studies was used as a threshold for stratifying selected evidence into "high" and "low"-dose subgroups. Heterogeneity was tested using chi-square statistics; inconsistency was measured with the I2 index. Pooled estimate was obtained by fitting both the fixed-effect and the DerSimonian and Laird random-effect model.Results: Eight studies and 401 patients were available for the meta-analysis; median follow-up was 32.8 months. The median delivered BED was 105.6 Gy(RBE). A BED >= 105.6 Gy(RBE) consistently provided superior OS, CSS, DFS and LC rates (i.e.: 4-year OS: 0.56 [0.34-0.76] for BED < 105.6 Gy(RBE) and 0.78 [0.64-0.88] for BED >= 105.6 Gy(RBE)). The meta-analysis of proportions showed a comparable probability of developing acute grade >= 2 toxicity between the two groups, while the probability of any late grade >= 2 event was almost three-times greater for BED >= 105.6 Gy(RBE), with rib fractures being more common in the high dose group.Concl