ESTRO 36 Abstract Book

S739 ESTRO 36 2017 _______________________________________________________________________________________________

Our data support that L5%P (alone or in association with other drugs) may be an effective and safe approach for FNP in cancer patients. EP-1397 Dose painting guided by diffusion-weighted MRI applied to recurrent glioblastoma: a phase I protocol M. Iori 1 , M. Galeandro 2 , A. Botti 1 , R. Sghedoni 1 , P. Ciammella 2 , M. Orlandi 1 , M. Napoli 3 , S. Tanzi 4 , R. Pascarella 3 , S. Cavuto 5 , A. Pisanello 6 , M. Russo 6 , E. Cagni 1 , D.E. Chiari 7 , M. Campioli 8 , C. Iotti 2 1 Arcispedale S. Maria Nuova - IRCCS, Medical Physics Unit, Reggio Emilia, Italy 2 Arcispedale S. Maria Nuova - IRCCS, Radiation Oncology Unit, Reggio Emilia, Italy 3 Arcispedale S. Maria Nuova - IRCCS, Neuroradiology Unit, Reggio Emilia, Italy 4 Arcispedale S. Maria Nuova - IRCCS, Palliative Care Unit, Reggio Emilia, Italy 5 Arcispedale S. Maria Nuova - IRCCS, Infrastructure Research and Statistic, Reggio Emilia, Italy 6 Arcispedale S. Maria Nuova - IRCCS, Neurology Unit, Reggio Emilia, Italy Purpose or Objective Standard treatment for glioblastoma (GBM) is surgery, followed by radio- & chemo-therapy. However, disease recurs in almost all patients and re-irradiation is an option to be considered. Although the topic of re-irradiation is generally controversial because of the toxicity risk, literature provides consistent data supporting both the feasibility and the survival-strengthening capability of radiation, compared to supportive care only. In the present study, voxel-based re-irradiations guided by magnetic resonance imaging (MRI) were simulated and planned with apparent diffusion coefficient (ADC) used as biomarker for tumor cellularity. Material and Methods The relapse areas of 6 selected GBM patients treated with STUPP protocol were monitored with MRI. The ADC patterns, considered in the literature as a surrogate biomarker of cellularity was analyzed and chosen to define a signal-to-dose transfer function. This decision, coupled with our clinical data in re-treating GBM with moderate hypo-fractionation regime (Ciammella et al, Clin Neurol Neurosurg, 2013, 115: 1609-14), have formed the basis of a phase I study undertaken on 12 GBM relapse patients, simulated with multi-parametric MRI and re-treated with a dose-painted hypo-fractionated regime. The study foresees dose levels of 30-50Gy/5fr with a cumulative BED 10 >120Gy in an attempt to achieve some changes in the recurrence pattern, without causing excessive radiation necrosis (<12 Gy/fr) inside the irradiated area and respecting the previously irradiated healthy tissue (EQD 2 < 100Gy). To realise the ADC data extraction and DPBN (Dose Painting By Numbers) planning procedure with RapidArc technique, home-made MATLAB software and automatic scripting procedure on a commercial treatment planning system (TPS) were realised. Nine target sub- volumes were used for the volume-based TPS plan optimisation. Phantom (PTW, Octavius 4D) and portal dosimetry (EPID) based on g-index (2%, 2mm) were applied for the pre-treatment plan evaluation. Results Considering follow-up data that correlates patient outcomes with histogram changes in the tumour recurrence ADC values of the 6 relapsed patients, a double threshold transfer function was defined. The first patient was enrolled in the study and treated. To a first control to three months after treatment, the first patient has not had acute toxicity, has a performance status of 100%, and has a radiological picture of stable disease albeit 7 UNITN, Dipartimento di Fisica, Trento, Italy 8 UNIMORE, Dipartimento di Scienze e Metodi dell’Ingegneria, Reggio Emilia, Italy

associated with signs of pseudo-progression. The pre- clinical check of the delivered treatment, verified with portal and phantom dosimetry, has provided a minimum g-index of 90.7%. The total beam-on time with 4 non- coplanar 6MV FFF arcs was less than 5 min. Conclusion The phase I protocol, approved by Ethical Committee, has enrolled its first patient. Data on planning, dosimetric and patient follow-up aspects will be presented and discussed. EP-1398 Application of radiosurgery in treatment of oligometastases T. Chebotarova 1 , N. Spizhenko 1 , N. Lisovzka 1 , O. Yarmak 1 1 Cyber Clinic of Spizhenko, Radiation therapy, Kapitanivka -Kyiv region, Ukraine Purpose or Objective Development of genetic researches in the field of oncology found out proofs of genomic instability in solid tumors which results in their clonal heterogeneity. Oligometastatic disease considered as an intermediate biological state with limited ability of tumor to promote numerous metastases. In this transition stage of growth tumor could gave oligometastatic clones expressed with single metastatic lesions. Now it’s known, that the cells of oligometastatic tumors expressed specific microRNAs able to block tumor-promoting genes, and as a result make the spread of tumors slower. We are focusing on the group patients with metastatic lesion aiming to detect clinical application for local ablative radiosurgery treatment. Material and Methods The results of treatment of 335 patients with metastases of brain, lung, liver, renal and epinephrine were analyzed. The localization of primary tumors in this group of patients was in breast, lung, colorectal and kidney. Performance status of patients was 0-1 according ECOG-scale. All patients have previously radically treated primary tumor and no more than 3-4 distant metastatic lesion by the moment of treatment. Patients receive radiosurgery or hypofractined irradiation in a single dose 6-20 Gy and total summary dose 20-60 Gy by using CyberKhife system. Results In 31 patients with distant metastases in brain, lung, liver, renal and epinephrine after local ablative radiosurgery we registered full tumor regression during 2-6 years. The existence of this group of patients clinically confirms molecular differences between higher and low metastatic potential tumors. That is why previously shown genetic features of oligometastatic tumors change our ideas about possibilities of active local treatment in cases of metastatic disease. Conclusion Thus, our observations clinically confirm the existence of group of patients with oligometastatic tumor disease caused by specific genomic changes in tumor cells. In such cases, local ablative radiosurgery with precision and high doses of radiation could be curative. EP-1399 Rotary-Dual Total Skin Electron Beam Therapy as palliative treatment for mycosis fungoides A. Jodda 1 , M. Pawlaczyk 2 , M. Fundowicz 3 , T. Piotrowski 4 1 Greater Poland Cancer Centre, Medical Physics, Poznan, Poland 2 Poznan University of Medical Sciences, Skin Diseases Prevention, Poznan, Poland 3 Greater Poland Cancer Centre, Radiotherapy, Poznan, Poland 4 Poznan University of Medical Sciences, Electroradiology, Poznan, Poland Purpose or Objective To retrospectively assess the efficacy and toxicity of a total skin electron beam therapy (TSEBT) in patients with primary cutaneous T-cell lymphoma at various stages of development.