ESTRO 2023 - Abstract Book

S797

Monday 15 May 2023

ESTRO 2023

related to the treatment) were calculated using the Kaplan-Meier estimator and compared in two different periods (treatments performed before or after 2010) using the log-rank test. Results A total of 185 patients, 65 (35%) with ALL and 120 (65%) with AML were included. Median age was 38 years (18-59) and 83 were women (45%); 61% were in first complete remission. Median follow-up for survivors: 1,6 years (1-27). Nineteen patients had IPS (10,3%), and 7 of them died early after transplant. Most IPS cases were diagnosed before 2010 (15% vs 4,7%; p= 0,028) and all them received lung doses over 8.5 Gy. The 1y/5y-DSS were 61,4%/47,9% and 90,2%/81,4% before and after 2020, respectively (p=0,000) (Fig.1). Multivariate analyses showed that pre-transplant abnormalities in baseline chest X Ray (p=0.001) and lung irradiation dose (p=0,005) were significantly associated with IPS development. In fact, the risk of pneumonitis increased four times for each Gy in the lungs. The 1y/5y-OS were 54%/37,7% before 2020 and 81%/69,5% after 2020 (p=0,000) (Fig2). Transplant period (before 2010), lung dose and development of pneumonitis were associated with lower OS (p=0,000). Fig 1. Disease specific survival (death due to leukemia or related to the treatment were computed as events) (In red, patients treated since 2010 an in blue, patients treated before 2010)

Fig 2. Overall survival (In red, patients treated since 2010 and in blue, patients treated before 2010)

Conclusion Our results suggest that use of individualized lung shields with maximum protection and avoidance of lung doses over 8.5 Gy are associated with lower lung toxicity without reducing long term survival in high risk AL patients receiving 13.5 TBI conditioning schedules. MO-0949 Phase 1 study of escalated total marrow irradiation and melphalan at 1st relapse in multiple myeloma A. Cailleteau 1 , P. Maingon 2 , S. Choquet 3 , R. Bourdais 2 , D. Antoni 4 , B. Lioure 5 , C. Hulin 6 , S. Batard 7 , C. Llagostera 8 , V. Guimas 1 , C. Touzeau 9 , P. Moreau 9 , M. Mahé 10 , S. Supiot 1 1 Institut de Cancérologie de l'Ouest, Radiation oncology, Nantes, France; 2 Hôpital Pitié-Salpêtrière, Radiation oncology, Paris, France; 3 Hôpital Pitié-Salpêtrière, Hematology, Paris, France; 4 ICANS, Radiation oncology, Strasbourg, France; 5 ICANS, Hematology, Strasbourg, France; 6 Hôpital universitaire Haut-Lévêque, Hematology, Bordeaux, France; 7 Institut Bergonié, Radiation oncology, Bordeaux, France; 8 Institut de Cancérologie de l'Ouest, Physics, Nantes, France; 9 Hôpital universitaire Hôtel Dieu, Hematology, Nantes, France; 10 Centre François Baclesse, Radiation oncology, Caen, France Purpose or Objective A second intensification is an option at first relapse in multiple myeloma (MM) after more than 36 months of initial remission. Many conditioning regimens have been tested, with or without total body irradiation (TBI). Recently, it was found that TBI could be replaced by total marrow irradiation (TMI) using helical Tomotherapy with promising results.