Abstract Book

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ESTRO 37

Purpose or Objective To assess the efficacy of repetitive low-dose involved- field radiotherapy in patients with indolent B-cell non- Hodgkin lymphoma (iNHL). Material and Methods All consecutive patients between January 1990 and December 2015 with iNHL treated with multiple courses of low-dose radiotherapy (LD-RT) 4 Gy (2 x 2 Gy) at our center were investigated. Response rates, duration of response, overall survival and local control were collected. Results Thirty-five patients (15 women and 20 men) were included; all treated with multiple courses of LD-RT 4 Gy (2 x 2 Gy). Median age was 57 years (range: 20-80), histological types were follicular lymphoma (69%), marginal-zone lymphoma (17%), cutaneous lymphoma (9%) and nodular lymphocyte predominant Hodgkin lymphoma (6%). Ann Arbor stage was I-II in 18 pts (51%), and III-IV in 17 pts (49%). With a median follow-up of 12.0 years (range: 2.3 - 24.5), median overall survival was not reached. At last follow-up, 69% (24/35) of patients remain in complete remission, 23% (8/35) present progressive disease and 8% (3/35) have stable disease. Furthermore, LD-RT was the last treatment modality received in 18/35 patients (51%), among who histological types were FL (n=10), MZL (n=5) and CT-FL (n=3). Four patients had died of disease progression (n=2), cardiac failure (n=1) and other cancer (hepatocellular carcinoma, n=1). None experienced diffuse large B cell lymphoma transformation. Considering all LD-RT sessions, overall response rate was 94%. The overall response rate after the first and the second LD-RT sessions were 97% and 89%, respectively (p=0.31). The median time for out-field progression was 1.6 and 1.5 year after the first and second low-dose radiotherapy course respectively (p=0.338). Estimated 1- and 3-year local control rates after first and second course of LD-RT were 94% vs 91% and 80% vs 85%, respectively (p=0.37). Considering all LD- RT sessions, estimated 1-, 2- and 5-years LC were 94% (95%CI: 89 - 99%), 88% (95%CI: 81 - 96%), and 83% (95%CI: 75% - 93%) respectively. Median time to local recurrence was not reached. Nodular lymphocyte predominant Hodgkin lymphoma patients was less likely responder to LD-RT compared to other lymphoma types (p=0.002). Conclusion Beyond a first course of LD-RT, a second course could be performed, with similar efficacy, duration of response and local control rates, in patients with iNHL. EP-1250 Ocular Adnexal lymphoma: a 12-years experience in an Institution S. Garcia 1 , D. Rodrigues 1 , R. Lago 1 , P. Chorão 2 , L. Osório 1 , P. Soares 1 , G. Pinto 1 1 Centro Hospitalar São João, Serviço de Radioterapia, Porto, Portugal 2 Centro Hospitalar São João, Serviço de Hematologia, Porto, Portugal Purpose or Objective The aim of the present retrospective study is to determine the overall survival (OS), disease specific survival (DSS) and the local control of primary and secondary adnexal orbital lymphoma treated with radiation therapy in an Institution. Early and late toxicity of radiation treatment (6 Mv photon, 3 DCRT) were also evaluated. Material and Methods All the patients with histology confirmed diagnosis treated with radiation therapy in our institution were included in this study. A population of 23 patients treated between January 2005 and March 2017 was obtained. Data related to median age at diagnosis, gender, laterality of the ocular lymphoma, histology, Ann-Arbor stage, frequency of primary or secondary disease, intent of radiation treatment, dose prescribed, and acute and

group, respectively (p = 0.085). On multivariate analysis for overall PT, dose rate of TBI ≥ 6 cGy/min (Hazard ratio [HR] 2.54, 95% confidence interval [CI] 1.22 – 5.28, p = 0.012) was associated with increased risk of PT occurrence. In subgroup analysis, the conventional group had increased risk of infectious PT (HR 2.63, 95% CI 1.13 – 6.14, p = 0.025) and risk of non-infectious PT (HR 4.08, 95% CI 0.91 – 18.26, p = 0.066). The overall survival rate was significantly affected by PT (p = 0.001). However, the overall survival, relapse, and TRM showed no significant difference between the conventional and reduced group. Conclusion About two-thirds of the patients undergoing daily TBI for pre-treatment of HSCT experienced PT, which affected overall survival. Reducing the dose rate of TBI decreased the risk of PT, without compromising the treatment efficacy in overall survival, relapse, and TRM. Based on the findings, we suggest reducing the dose rate to less than 6 cGy/min for daily TBI treatment. EP-1248 Evaluation of the treatment with a single- fraction dose of radiation for mycosis fungoides. K. Okuma 1 , W. Takahashi 1 , S. Sawayanagi 1 , K. Nakagawa 1 1 University of Tokyo Hospital, Radiology, Tokyo, Japan Purpose or Objective Local electron and/or X-ray radiation therapy is used for stage I-II Mycosis fungoides (MF). In the past, treatment with a total dose of 20-40 Gy was given in multiple fractions. Recently, a low-dose RT schedule applied to palliate symptoms for patients with MF was reported. This study aimed to assesses the clinical response in patients treated with a single fraction of radiation in patients with MF. Material and Methods This study involved a review of the records of 30 patients with MF treated with a single fraction or multiple fractions of palliative radiation therapy (RT) between August 2010 and October 2017. Patient and tumor characteristics were reviewed. Results Three hundred individual lesions were treated: 201 lesions (67%) were treated with 8Gy in a single fraction, 26 lesions (9%) with 8Gy in 2 fractions, and other lesions were treated in multifractionated radiation; the mean follow-up was 7.9 months (range, 0-79.6 months). The median age was 66 years (range, 25-92 years). There were 21 males and 9 females. The median number of treatment lesions per patient were five (range, 1-51). Response rate by lesion was assessed, with a complete response (CR) in 270 (90%) lesions, a partial response in 24 (8%) lesions, and no response in 3 (1%) lesion. The frequency of acute >grade 1 toxicity was significantly higher in the multifractionated radiation group than in the single-fraction radiation group. However, no statistically significant difference was observed with regard to severe late toxicity. The cost of multifractionated radiation was >200% higher than that for single-fraction radiation. Conclusion This study suggests that a single fraction of 8 Gy offers excellent palliation for MF lesions and is cost effective and convenient for the patient. EP-1249 Repeated low-dose radiation therapy in indolent Non-Hodgkin Lymphoma patients K. Saleh 1 , J.M. Michot 1 , A. Schernberg 2 , A. Danu 1 , J. Lazarovici 1 , D. Ghez 1 , T. Girinsky 2 , N. Khalife-Saleh 1 , R. Mazeron 2 , V. Ribrag 1 , A. Boros 2 1 Gustave Roussy cancer campus, Hematology, paris, France 2 Gustave Roussy cancer campus, radiation oncology, paris, France