Abstract Book

S241

ESTRO 37

PV-0469 Preliminary results of a phase i trial on VMAT radiosurgery in primary or oligometastatic cancer F. Deodato 1 , G. Macchia 1 , A. Ianiro 2 , M. Nuzzo 3 , S. Mignogna 4 , A. Di Paolo 4 , G. Siepe 5 , G. Tolento 5 , R. Frakulli 5 , G. Zanirato 6 , E. Galofaro 5 , V. Dionisi 5 , S. Cammelli 5 , A. Arcelli 5,7 , V. Valentini 8 , A.G. Morganti 5 , S. Cilla 2 1 Radiotherapy Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy 2 Medical Physics Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”- Università Cattolica del S. Cuore, Campobasso, Italy 3 Radiation Oncology Department, Università "G. D’Annunzio", Chieti, Italy 4 Medical Oncology Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”- Università Cattolica del S. Cuore, Campobasso, Italy 5 Radiation Oncology Center, Department of Experimental- Diagnostic and Specialty Medicine – DIMES- University of Bologna- S. Orsola-Malpighi Hospital, Bologna, Italy 6 Radiology Unit, Department of Diagnostic and Preventive Medicine- S. Orsola-Malpighi Hospital, Bologna, Italy 7 Radiation Oncology Unit, Bellaria Hospital, Bologna, Italy 8 Radiation Oncology Department Gemelli-ART, Fondazione Policlinico Agostino Gemelli- Università Cattolica del S. Cuore, Roma, Italy Purpose or Objective To report the ongoing results of a Phase I trial testing extracranial stereotactic body radiosurgery (SBRS) delivered by volumetric intensity modulated arc therapy in primary or metastatic cancer patients Material and Methods Each enrolled patient was included in a different phase I study arm, according to tumour site and disease stage (lung, liver, bone, advanced), and sequentially assigned to a dose level established by the protocol. Acute and late toxicity, tumour response and early local control were investigated and reported

Conclusion To date, only one patient experienced dose limiting toxicity and tumour response, local control rate and toxicity profile appear encouraging. The maximum tolerable dose has not yet been reached in any study arm PV-0470 Extracranial SBRT: impact of functional response on local control F. Deodato 1 , S. Cilla 2 , G. Macchia 1 , A. Ianiro 2 , M. Boccardi 1 , E. Arena 1 , G. Restaino 3 , B. Carabellese 4 , M.R. Grivet 4 , G. Tolento 5 , A. Zamagni 5 , C.M. Donati 5 , L. Ronchi 5 , M. Ferioli 5 , S. Cammelli 5 , A.G. Morganti 5 1 Fondazione di Ricerca e Cura “Giovanni Paolo II”, Radiotherapy Unit, Campobasso, Italy 2 Fondazione di Ricerca e Cura “Giovanni Paolo II”- Università Cattolica del S. Cuore, Medical Physics Unit, Campobasso, Italy 3 Fondazione di Ricerca e Cura “Giovanni Paolo II”- Università Cattolica del S. Cuore, Radiology Unit, Campobasso, Italy 4 “A. Cardarelli” Hospital, Nuclear Medicine Unit, Campobasso, Italy 5 of Experimental- Diagnostic and Specialty Medicine – DIMES- University of Bologna, Radiation Oncology Center, Bologna, Italy Purpose or Objective The tumoral and adjacent peritumoral modifications caused by radiosurgery limit the evaluation of response by anatomic imaging and dimensional criteria alone, such as with RECIST. This suggests that it is of interest to also take into account the functional criteria evaluated with PET-CT than routine imaging and metric evaluation alone. Therefore, we were prompt to evaluate the impact of functional response on local control in a large series of patients undergoing extracranial stereotactic radiotherapy (SBRT) in our centre Material and Methods Data of patients with oligometastatic disease (less than 5 visceral and/or bone metastases), undergone 5 fractions SBRT (DESTROY-1 phase I clinical trial) or single fraction stereotactic radiosurgery (SRS-DESTROY-2 phase I clinical trial) as exclusive treatment, retreatment or boost after 3D-CRT, were collected and analyzed. Patients were enrolled from September 2003 to April 2017, therefore SBRT planning was performed previously by 3D conformal non-coplanar beam arrangement, subsequently by volumetric arc technique. The functional response was evaluated by FDG-PET/CT or Choline-PET/CT 3-6 months after SBRT. Objective response rate (ORR) included complete and partial response. Clinical benefit included ORR and stabilization of disease. The 95% confidence intervals (95% CI) have been provided. Local control (LC) of irradiated lesions was calculated using the Kaplan- Meier method from the date of SBRT to the date of the inside SBRT field relapse/progression of disease or the date last seen Results 427 consecutive patients (M/F: 255/172; median age: 69, range 35-93) with 582 lesions were treated. Of these, 159 were primary or metastatic lung tumours, 49 were liver metastases, 93 were bone metastases, 229 lymph nodal metastases and 52 miscellanea of neoplastic lesions. Dose prescription varied from 8 Gy/single fraction (boost after a previous radiotherapy dose) to 50 Gy/5 fractions to the Planning Target Volume. Median follow-up was 16 months (1-157). ORR based on CT/MRI/PET was 79.9 % (CI 95%: 75.8-83.4) with a complete response rate of 57.4% (CI 95%: 52.6-62.9). 12-and 24-months actuarial local control (freedom from progression in the irradiated site) was 86.2% and 76.2%, respectively. Patients with a complete functional response had better 2-year local control than those with the worst response (90.2% versus 56.1%; chi- squared p= 0.0001) (Figure).

Results 185 lesions in 121 consecutive patients (M/F: 72/49 median age: 69; range 40-93) were treated. Of these, 40 were primary or metastatic lung tumours, 36 were liver metastases, 66 were bone metastases, 41 lymph nodal metastases, 1 was a primary pancreatic tumours and 1 was a primary vaginal tumour. Dose prescription ranged from 12 to 30 Gy in single fraction to the Planning Target Volume. Median follow-up was 15 months (1-68). Only 1 patient had a dose limiting toxicity (grade >3). The grade 1 and 2 toxicity rate was 16.7% e 2.7% respectively (CTCAE 4.03). Overall response rate based on CT/MRI was 75.7 % (CI 0.95 : 68.2%-83%) with a complete response rate of 52.4% (CI 0.95 : 44.5%-61.7%). Actuarial local control (defined as irradiated site progression freedom) was 77.7% and 63.4% at 2 and 4 years