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BackgroundRadiotherapy in Hodgkin’s Lymphoma (HL) is currently evolving with new attempts to further reduce radiation volumes to the involved-node concept (Involved Nodes Radiation Therapy, INRT) and with the use of intensity modulated radiotherapy (IMRT). Currently, IMRT can be planned and delivered with several techniques, and its role is not completely clear. We designed a planning study on a typical dataset drawn from clinical routine with the aim of comparing different IMRT solutions in terms of plan quality and treatment delivery efficiency.MethodsA total of 10 young female patients affected with early stage mediastinal HL and treated with 30 Gy INRT after ABVD-based chemotherapy were selected from our database. Five different treatment techniques were compared: 3D-CRT, VMAT (single arc), B-VMAT (“butterfly”, multiple arcs), Helical Tomotherapy (HT) and Tomodirect (TD). Beam energy was 6 MV, and all IMRT planning solutions were optimized by inverse planning with specific dose-volume constraints on OAR (breasts, lungs, thyroid gland, coronary ostia, heart). Dose-Volume Histograms (DVHs) and Conformity Number (CN) were calculated and then compared, both for target and OAR by a statistical analysis (Wilcoxon’s Test).ResultsPTV coverage was reached for all plans (V95% ≥ 95%); highest mean CN were obtained with HT (0.77) and VMAT (0.76). B-VMAT showed intermediate CN mean values (0.67), while the lowest CN were obtained with TD (0.30) and 3D-CRT techniques (0.30). A trend of inverse correlation between higher CN and larger healthy tissues volumes receiving low radiation doses was shown for lungs and breasts. For thyroid gland and heart/coronary ostia, HT, VMAT and B-VMAT techniques allowed a better sparing in terms of both Dmean and volumes receiving intermediate-high doses compared to 3D-CRT and TD.ConclusionsIMRT techniques showed superior target coverage and OAR sparing, with, as an expected consequence, larger volumes of healthy tissues (lungs, breasts) receiving low doses. Among the different IMRT techniques, HT and VMAT showed higher levels of conformation; B-VMAT and HT emerged as the planning solutions able to achieve the most balanced compromise between higher conformation around the target and smaller volumes of OAR exposed to lower doses (typical of 3D-CRT).

Stereotactic Ablative Radiotherapy (SABR) has been previously investigated as an alternative to thoracic surgery in patients with a limited number of pulmonary nodules from different primary tumors. We here report the clinical outcomes of a series of consecutive patients homogenously selected and treated with single dose SABR in our Institution. Eligibility criteria were: 1-5 lung metastases, maximum tumor diameter 50 mm, absent or controlled extra-thoracic disease, adequate pulmonary function, no prior radiotherapy, performance status ECOG 0-1. All patients were treated with a single dose of 26 Gy prescribed to the months. Treated metastasis progression at SABR site was observed in 10 lesions (11.1%), and actuarial LC rates at 1 and 2 years were respectively 93.4% and 88.1%. Systemic failure occurred in 37 patients (55.2%) at a median interval of 8 months after SABR. PFS rates were 72% and 55.4% at 1 and 2 year. Seven patients had grade 1 (10.4%) and 8 grade 2-3 late radiological toxicity (11.9%), while 6 experienced late chest wall toxicity (2 rib fractures, 4 chronic chest pain, 8.9%). CSS rates at 1 and 2 years were 90% and 76%, while OS rates were 85.1% and 70.5%, respectively. Median survival time was 40 months. On multivariate analysis, a disease-free interval longer than 24 months was close to significance for a benefit in CSS (p 5 0.07; HR 0.34 [95% CI 0.1-1.12]). The study includes a cohort of patients treated with single fraction 26 Gy SABR followed for a prolonged time interval. Single fraction SABR appears to be an effective treatment option, with little observed acute toxicity and limited late toxicity (15%); its advantages also include a high patients' compliance, a short overall treatment time and an easy combination with systemic therapies. These results might provide supportive evidence to the use of single fraction SABR as a valid and acceptable alternative to surgery for pulmonary metastases from different primary tumors.

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