DIBH-VMAT for Consolidation RT in Mediastinal B-NHL can Significantly Reduce Doses to OAR Report of Two Cases

Abstract

has shown to improve significantly both overall survival (OS) and progression-free survival (PFS) even in the rituximab era significantly and also in patients with nonbulky-disease [1-3]. The advances with chemotherapy and radiotherapy have considerably increased the survival rates. Most of the patients are in a middle age of 50 to 60 years and the treatment is in principle curative with a five year PFS of 75-90%. Therefore on the one hand, DLBCL has to be adequately treated to reach a curative outcome, on the other hand RT-delivery should avoid critical dose burden to organs at risk, i.e. especially the heart and the lungs, in order to reduce late cardiac morbidity and the risk for secondary lung cancer. In Hodgkin´s disease, the relative risk (RR) of secondary lung cancer increases considerably in relation to the dose of ionizing radiation, with a RR of 9.6 when more than 9 Gy are administered [4]. Less is known about the correlation between NHL and second lung cancer. Although, the RR is higher in long-term NHL survivors than in healthy individuals. The risk for cardiac mortality and secondary cancers can be estimated using calculation models. Toltz, et al. used the relative seriality model to predict excess risk of cardiac mortality and a modified linear quadratic model to predict the Excess Absolute Risk (EAR) for induction of lung cancer and breast cancer in patients with Hodgkin´s Lymphoma, NHL or breast cancer [5]. They compared the results of 3D conformal photon radiotherapy (3D-CRT) and intensity modulated proton therapy (IMPT). The excess risk of cardiac mor-Abstract Background: Consolidative radiotherapy after immunochemotherapy in localized bulky diffuse large B-cell lymphoma (DLBCL) patients significantly improves both, overall and progression-free survival and treatment is in principle curative. Therefore protection of organs at risk is highly relevant. Case, planning and results: Two 53-years and 18-years old patients with bulky mediastinal DLBCL were planned with and without deep inspiration breath-hold (DIBH) and volumetric modulated arc therapy (VMAT). DIBH reduced the doses to the heart and the lungs while homogeneity and conformity were not compromised. The number of Monitor Units (MU) needed was significantly reduced by DIBH-VMAT. Both patients were treated in DIBH-VMAT. Conclusion: Planning with DIBH in bulky mediastinal DLBCL is feasible and should be taken into account due to the high relevance with regard to acute and late toxicity.