ESTRO 2020 Abstract book

S532 ESTRO 2020

From February 2011 to December 2018, 20 patients with R/R HL (n=7), Diffuse Large B Cell NHL (n=11) and T-cell NHL (n=2) were treated. The median age was 42 years (range 20-68) and median previous lines of therapy were 3 (range 2-4). All the NHL were minimum stage III at diagnosis. Four patients had already received prior ASCT. The TLI total dose of 12 Gy was delivered in a daily fraction of 4 Gy for 3 consecutive days. HDCT was administered 4 days later. Conditioning chemotherapy consisted of high- dose Bendamustine (400 mg/sqm) and Melphalan 140 (mg/sqm) for patients older than 40 years (n=10) and conventional FEAM (Fotemustine, Ethoposide, Cytarabine and Melphalan) for younger patients. Results Salvage chemotherapy-induced CR in 9 patients (5 HL, 4 NHL), PR in 5 (2 HL, 3 NHL), less than PR in 6. Eight patients (40%) experienced fever of unknown origin and 8 patients (40%) developed grade 3/4 mucositis. None experienced other grades 3/4 extra-hematological toxicity. The median number of CD34+ cells infused was 5,5 x 106/kg (range 2,1 -11,6). All patients showed complete engraftment, the median time to neutrophil and platelet recovery was 11 (range 9-21) and 12.5 days (range 9-21) respectively. Median follow-up was 64.9 months (CI 95% 22.5-107.3 months). All patients in PR or less before transplant achieved CR. No cases of treatment-related death were recorded. The 3-year overall PFS and OS were 55.5% and 72.8% (Fig) respectively. Post-ASCT relapse occurred in 9 patients (HL=2 and NHL=7) at a median time of 8 months. Conclusion Our preliminary results show that 4 Gy daily TLI is safe in advanced NHL and HL. With the limit deriving from the small size of this series, we observe that all patients achieved CR after the procedure, and that the relapse rate was relatively low, altough the total radiation dose was low. All the imaging is under centralized revision to identify potential bias. PO-0912 Role of salvage radiotherapy in relapsed/ refractory DLBCL in the rituximab era: A meta-analysis F. KazmI 1 , B. Vellayappan 2 , Y. Kheng Wei 3 , I. Sin Huili 3 , B. Fei Tan 3 , S. Poh Shuxian 3 1 Churchill Hospital, Oncology, Oxford, United Kingdom ; 2 National University Hospital Singapore, Radiation Oncology, Singapore, Singapore ; 3 National Cancer Centre Singapore, Radiation Oncology, Singapore, Singapore Purpose or Objective The role of salvage radiotherapy in patients with relapsed/ refractory (r/r) Diffuse Large B-Cell Lymphoma (DLBCL) is unclear in the rituximab era. We sought to determine the efficacy and toxicity of radiotherapy for this group of patients. Material and Methods We searched MEDLINE and various conference proceedings for eligible studies where patients were treated with salvage radiotherapy for r/r DLBCL, excluding patients that received consolidation radiotherapy as first line treatment. Outcomes of interest were 2 and 5-year overall survival (OS-2, OS-5), 2 and 5-year freedom from progression (FFP-2, FFP-5) and Grade 3 or 4 adverse events (AE). We used random effects model to pool outcomes across studies and compared pre-defined subgroups using interaction test. Results We found 13 eligible non-comparative studies with methodological limitations identified. The studies included 412 patients who received rituximab based chemotherapy as first-line treatment. Of these, 2 were of a prospective design, 3 studies used peri-stem cell transplant radiotherapy, and 3 involved radiotherapy to primary mediastinal lymphoma. We found that salvage radiotherapy was associated with a OS-2 rate of 94% (95% confidence interval (CI) 84 – 95%, I 2 = 55%), OS-5 rate of 83% (95% CI 76 – 89%, I 2 = 64%), FFP-2 rate of 81% (95% CI

We identified 112 patients treated with external beam radiotherapy between January 2003 and December 2014. The median follow-up for all patients is 51 months (range 1-185 months). There were 69 patients irradiated with 2D technique and 43 using 3D conformal radiotherapy (3DCRT). Median dose was 36 Gy, range 4 to 54 Gy. Medium dose per fraction was 2 Gy, range 1.5 to 7 Gy. Data for long-term side effects were available for 80 patients. Results Five and 10-year overall survival (OS) rates were 69% and 58% respectively and 5 and 10-year event-free survival rates (PFS) 59% and 57% for all patients. The in-field and out-of-field recurrence rates were 5% and 21%. Patients with indolent NHL had 5 and 10-year OS rates of 84% and 63% respectively, and 5 and 10-year EFS rates of 54% and 48%. In patients with aggressive NHL 5 and 10-year OS was 75% and 64% respectively and 5 and 10-year EFS 65% and 65%. OS and EFS was significantly better in the group of patients that were irradiated after one line than after two or more lines of chemotherapy (5-years OS 87% vs. 68%, p =0.001 and EFS 72% vs. 28%, p <0.001). Acute toxicity occurred in 43% patients; gastrointestinal in 26% and hematological in 15%. 2D radiotherapy resulted in more hematologic toxicity than 3D conformal (31% vs. 7%, p= 0.007). Nausea occurred in 10% patients in 2D group and in 28% patients in 3D group (p= 0.020). Long-term side effects were noted in 15% of patients; gastrointestinal in 5%, renal in 4% and secondary malignancy in 2%; there was no significant difference between patients irradiated using 2D and 3D technics. Conclusion Radiotherapy is an effective and safe treatment option for patients with infradiaphragmatic lymphoma providing excellent local disease control with minimal late toxicity. The difference in toxicity between older and newer radiation technics seems less pronounced than for supradiaphragmatic fields. Infradiaphragmatic lymphoma localization should not be regarded as a contraindication for use of radiotherapy. PO-0911 Volumetric total lymphoid hypofractionated irradiation and stem cell transplantation in lymphomas. S. Vagge 1 , F. Guolo 2 , F. Ballerini 2 , S. Agostinelli 3 , D. Tramontano 4 , I. Chiola 4 , E. Olivetta 4 , R. Corvò 4 , E. Angelucci 2 , R. Lemoli 5 1 IRCCS Ospedale Policlinico San Martino, Radiation oncology, Genova, Italy ; 2 IRCCS Ospedale Policlinico San Martino, Hematology, Genova, Italy ; 3 IRCCS Ospedale Policlinico San Martino, Medical Physics, Genova, Italy ; 4 Università degli Studi di Genova, Radiation Oncology, Genova, Italy ; 5 Università degli Studi di Genova, Hematology, Genova, Italy Purpose or Objective Salvage chemotherapy followed by autologous stem cell transplantation (ASCT) is the standard of care for patients with relapsed/refractory (R/R) lymphomas. Involved site radiotherapy (ISRT) showed a potential benefit before or after ASCT in Hodgkin disease (HL). Data about the efficacy of ISRT and ASCT in non-Hodgkin lymphomas (NHL) are lacking. In ASCT plus ISRT, progression and relapse are lower if radiotherapy is performed over all the disease sites that emerged from the diagnosis (Wirth 2019). Total Body Irradiation is a viable alternative to chemotherapy in the conditioning regimen for NHL (Tseng 2018). This suggestion reinforces the potential role of large fields as total lymphoid irradiation (TLI) in R/R patients with an advanced stage of disease at diagnosis. Hyperfractionated TLI, before ASCT, has already shown promising results in advanced HL (Evans 2007; Gentzler 2014; Rimmer 2017). Our study aimed to assess the feasibility of TLI, delivered with an hypofractionated schedule by helical tomotherapy, followed by high dose chemotherapy (HDCT) for ASCT in R/R NHL and HL. Material and Methods