Residual Site Radiotherapy After Immunochemotherapy in Primary Mediastinal B-Cell Lymphoma: A Monoinstitutional Retrospective Study

Abstract

Aim: To evaluate the efficacy of residual site radiation therapy (RSRT) on local control (LC), progressionfree (PFS) and overall (OS) survival in patients with primary mediastinal lymphoma (PMBCL), following rituximab and chemotherapy treatment (ICHT). Patients and Methods: The study included 34 patients with PMBCL treated between 2006 and 2014 with ICHT with/without autologous stem cell transplantation and RSRT. Between the end of ICHT/stem cell transplantation and RSRT, patients were evaluated with 18 F-fluorodeoxyglucose positron-emission tomography. The gross tumor volume included morphological mediastinal residual disease after ICHT/SCT. The percentage of LC, PFS and OS were assessed. Results: All patients received RSRT with a median dose of 30 Gy. Median follow-up was 82 months. One patient out of 34 (3%) showed progressive disease 9 months from diagnosis. The 10-year PFS and OS were 97% and 97% respectively. Conclusion: RSRT in patients with PMBCL treated with ICHT did not impact unfavorably on LC and patient survival. Primary mediastinal B-cell lymphoma (PMBCL) is a distinct clinicopathological entity that accounts for 2-4% of non-Hodgkin's lymphomas. It is characterized by a locally aggressive presentation with a large mediastinal mass, more frequently in young women between the third and the fourth decade (1, 2). The presence of bulky mediastinal disease >10 cm is not uncommon, with extension into the contiguous chest wall, lung and pericardium. A combined approach with doxorubicin-based chemotherapy and adjuvant mediastinal radiotherapy (RT) has been evaluated in retrospective series, most of them performed in the pre-rituximab era, showing a 5-10 years progression-free survival (PFS) of 57-81% (2-5). More recently, the addition of rituximab to the doxorubicinbased chemotherapy schedules (ICHT) and adjuvant RT demonstrated survival improvement, with 3-to 5-year PFS of 80% and overall survival (OS) 83%-88% (1, 2, 6, 7). Although there is a lack of randomized studies, ICHT and adjuvant RT are considered part of the standard of care in the treatment of PMBCL in Italy (2). However, a high cure rate with a 5-year PFS of 93% has been also reported following treatment based on the R-DA-EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin and rituximab) schedule, without adjuvant RT, but these results, similarly, lack validation by randomized multicentric studies 1407 This article is freely accessible online.

Efficacy of Residual Site Radiation Therapy (ISRT) in Patients with Primary Mediastinal Lymphoma with Deauville Score 4 Following R-CHT: Results of a Retrospective Mono Institutional Study

“…Treatment approaches are based on systemic chemo-immunotherapy with or without adjuvant mediastinal radiotherapy. While after DA-R-EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab), adjuvant radiotherapy (RT) was not considered, after R-CHOP/R-MACOP-B, mediastinal radiotherapy has been routinely used in an adjuvant setting in clinical practice [2][3][4]. Interest has increased in evaluating whether post-immunochemotherapy 18-fluorodeoxyglucose 2 of 9 (FDG) positron emission tomography computed tomography (PET-CT) can be valuable for guiding subsequent treatment decisions for patients with PMBCL, especially when considering mediastinal adjuvant RT.…”