ESTRO 2020 Abstract Book

S488 ESTRO 2020

IMRT/VMAT (n = 3; 3.3%) techniques. The estimated Kaplan-Meier PFS for 5 and 10 years were 67.3% and 55.8%, respectively (median 102 months). The 5 and 10 year LC was 95.2% and 93.0%, respectively, the median was not reached. The 5- and 10-year-OS were 84% and 73.7%, with a median OS of 137 months. A univariate analysis of PFS showed that modern radiation techniques with 3D/IMRT/VMAT were associated with significantly better 5-year PFS than 2D (71.7% and 44.4%, p= 0.034). Patients who were treated with definitive radiotherapy had significantly improved PFS compared to patients who received any prior treatments (5-year PFS 75.4% and 54.9%, p= 0.016). Dose-escalation >36.0Gy, gender, histology, and age had no prognostic influence on PFS. The most common acute side effects were: dermatitis CTCAE °I-II (n=8), xerostomy CTC °I (n=10), cataract CTC°I (n=9), and dry eyes CTC °I-II (n=11). No serious adverse event CTC° III was reported.

of the treatment and had at least 6 months of follow-up or were followed until death. Results Three-hundred fifty-nine (359) patients were selected, with a median age at diagnosis of 57.7 years (13-90 years). Median follow-up was 48.0 months. Female patients were 51.3% and most had a good performance in the ECOG scale (78.8% are ECOG 0-1). Median overall survival was not reached, but mean OS was 50.1 months with 86 deaths. Median progression-free survival was 48.7 months. HIV infection had no impact on OS (p=0.580) or PFS (p=0.347) among patients treated with RT. HIV positive patients were more frequently staged only with CT (p>0.05) with no impact on PFS (p=0.191). No HIV positive patient received rituximab due to local policy restrictions and HIV positive patients were more prone to receive CHOP-like chemotherapy (p<0.05), specially ones with etoposide (CHOEP). CHOP was associated with better survival (p=0.015) in the overall population and in the HIV negative population (p=0.002), but not in the HIV positive population (p=0.982). RT toxicities were not overall more frequent in the HIV positive population (p=0.567), except for fatigue (p<0.05) and hematological toxicities HIV status did not impact on survival when patients are treated with consolidative radiotherapy. For HIV positive patients it seems to be an increase in fatigue and hematological toxicities of any grade with radiation. PO-0915 Clinical Activation Of An Efficient Low-Dose Total Body Irradiation Using The Tomodirect Approach A. Chiara 1 , S. Broggi 2 , G. Salvadori 1 , J. Peccatori 3 , A. Assanelli 3 , S. Piemontese 3 , M. Pasetti 1 , S. Selli 1 , R. Calandrino 2 , F. Ciceri 3 , C. Fiorino 2 , N. Di Muzio 1 1 Ospedale San Raffaele IRCCS, Radiation Oncology, Milan, Italy ; 2 Ospedale San Raffaele IRCCS, Medical Physics, Milan, Italy ; 3 Ospedale San Raffaele IRCCS, Haematology and Bone Marrow Transplantation Unit, Milan, Italy Purpose or Objective The feasibility of a low dose sub-mieloablative total body irradiation (TBI) technique using TomoDirect approach was investigated. The definition of a semi-automatic planning optimization procedures was explored and clinically implemented. First clinical results were also reported. Material and Methods TBI delivery was split in two parts: an upper plan from the head to half leg and a lower part, including all legs. The PTVs (PTV_upper and PTV_lower) were defined as the whole body, cropped by 3 mm from the external body contour. Four patients were selected for an in-silico investigation to optimize the irradiation geometry and the optimal plan parameters. For the upper plan a field width equal to 5 cm and a pitch equal to 0.5 were set for all simulations: five different modulation factor (MF) values and 3 different ballistic (6, 8 and 12 fields) were considered. For the PTV_lower plan two anterior/posterior beams with a field width of 5 cm, a pitch of 0.5 and a modulation factor equal to 1.5 were used. For each optimization an automatic process with 300 and 100 iterations was used, respectively for the upper and the lower plan. Between May 2018 and July 2019 twenty patients (13 male and 7 female) were treated by applying the optimal automatic solution assessed by the in-silico investigation. All patients, candidate to allogenic transplant after conditioning regimen with TBI and high dose chemotherapy, were treated with a low-dose TBI regimen: 12 patients with 4 Gy (2 Gy/day;2 fraction) and 8 with a single 2 Gy session. Results For the upper plan, the optimal compromise between treatment time and PTV coverage/ homogeneity was found for MF equal to 1.5 and 8 equidistant beams. All clinical plans were automatically optimized with the found (p=0.022). Conclusion

Conclusion Radiotherapy of iNHL demonstrated high effectiveness with no serious side effects in our cohort. Advances in radiation techniques with more precise irradiation volumes and conformal dose coverage was able to reduce toxicity while maintaining the therapeutic effectiveness PO-0914 Impact of HIV infection on consolidative radiotherapy for non-Hodgkin diffuse large B-cell lymphoma C. Trindade Mello Medici 1 , L. Coelho Casimiro 2 , A. Adolfo Guerra Soares Brandão 3 , G.P. Mauro 4 1 Barretos Cancer Hospital, Radiotherapy, Porto Velho, Brazil ; 2 Instituto do Câncer do Estado de São Paulo ICESP, Radiotherapy, Sao Paulo, Brazil ; 3 Instituto do Câncer do Estado de São Paulo ICESP, Hematology, Sao Paulo, Brazil ; 4 University of Sao Paulo, Radiology and Oncology, Sao Paulo, Brazil Purpose or Objective Even though frequent, it is not known how HIV infection and treatment impact in the consolidation by radiotherapy of non-Hodgkin diffuse B-cell lymphomas (DBCL) Material and Methods A retrospective cohort of DBCL patients treated with chemotherapy and consolidative radiotherapy between 2010 and 2018 was assessed. All patients had biopsy- proven lymphoma and were included if radiation was part