Abstract Book

S874

ESTRO 37

Results Thirty patients with 40 areas including 15 scalps, 10 arms, 7 cheeks and 8 legs were treated with median follow up of six months. The average size of the fields treated was 60 cm². Acute toxicity was manageable, quality of life improved, the need for further therapy for invasive disease decreased and there were no long term side effects at this early stage. Conclusion VMAT field therapy is safe and effective at six months. Longer follow up is needed to assess long term oncological outcome and quality of life. EP-1625 Cyberknife Radiosurgery On Brain Metastases From Melanoma In The Era Of Systemic Target Therapy. G. Fanetti 1 , G. Marvaso 1 , D. Alterio 1 , A. Ferrari 1 , D. Sibio 1 , C. Francia 1 , E. Cocorocchio 2 , L. Pala 2 , E. Rondi 3 , S. Vigorito 3 , B. Jereczek-Fossa 1 1 IEO - European Institute of Oncology, Division of Radiation Oncology, Milano, Italy 2 IEO - European Institute of Oncology, Division of Melanoma and Sarcoma Medical Oncology, Milano, Italy 3 IEO - European Institute of Oncology, Unit of Medical Physics, Milano, Italy Purpose or Objective To evaluate neurotoxicity and clinical outcome in patients (pts) treated with Stereotactic Radiotherapy/Radiosurgery (SRS) delivered by Cyberknife® and concomitant target therapy (i.e. immunotherapy and protein kinase inhibitors) to brain metastases from Melanoma (MBM). Material and Methods Data were collected retrospectively. Inclusion criteria consisted in: 1) histologic proof of melanoma, 2) brain metastases diagnosed with Magnetic Resonance Imaging (MRI), 3) systemic treatment with anti CTLA4, anti-PD1 or BRAF inhibitor ± MEK inhibitor 4) RSR delivered concurrently or within 6 weeks before or after the systemic therapy. Progression Free Survival (PFS), Brain- PFS (b-PFS), Overall Survival (OS) and Local Control (LC) were elaborated with Kaplan-Meier curves and defined as time between the end of SRS and clnical progression at any site, brain progression, death or last follow up and in field progression, respectively. Neurotoxicity was evaluated as headache, nausea/vomiting, seizure and scored with Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Neurotoxicity and radionecrosis were collected every 2 months with clinical examination and MRI. Results Fifty-eight MBM were treated in 26 pts (median age 54 years, range 34-81 years, 15 male). Primary tumor occurred in head and neck district, body, extremities and mucosae in 3, 13, 6 and 4, respectively. BRAF mutation was found in 13 pts. Median time from primary treatment and SRS was 42.4 months (range: 16.7-220.6). Systemic therapy consisted of anti CTLA4, anti-PD1 and BRAF inhibitor ± MEK inhibitor in 9, 6 and 11 pts, respectively. All pts received premedication with dexamethasone before SRS. Median dose delivered was 21 Gy in single fraction (range: total dose 15-36 Gy in 1-3 fractions). SRS was delivered at the time of first, second, third and fourth line of systemic treatment in 9, 10, 5 and 2 pts, respectively. The median follow up was 8 months (range: 1.5-27.7). At six months PFS, b-PFS, OS and LC were 30, 54, 65 and 60%, respectively. Only 2 out of 23 evaluable pts complained headache G1 after SRS (2 pts died before

Figure 1 - Kaplan-Meier overall survival curve for the 78 patients

Conclusion In this uncommon scenario, the survival is poor. Contributory factors may be older age with associated comorbidities. However, relapse within the treated regional lymph node and distant metastasis were also frequent. Multivariate analysis will be needed to examine the impact of possible prognostic factors to guide future studies aimed at improving prognosis for these patients: this may include identifying an optimal radiation dose and identifying patients at high risk of distant metastasis for clinical systemic trials. EP-1624 Forty large convex fields of skin cancer treated with volumetric arc therapy in Australia. G. Fogarty 1 , N. Molloy 1 , M. Fay 2 , A. Kaminski 3 , D. Schlect 3 , D. Christie 4 , L. Spelman 5 , R. Sinclair 5 1 Genesis Cancer Care- St Vincent's Hospital- Sydney, Radiation Oncology, Crows Nest, Australia 2 Genesis Cancer Care- Lake Macquarie Private Hospital- Newcastle, Radiation Oncology, Newcastle, Australia 3 Genesis Cancer Care- Wesley Hospital- Brisbane, Radiation Oncology, Brisbane, Australia 4 Genesis Cancer Care- Nambour Hospital- Gold Coast, Radiation Oncology, Gold Coast, Australia 5 Gabba Dermatology, Dermatology, Brisbane, Australia Purpose or Objective Australia has the highest incidence of skin cancer in the world. Some patients suffer with large fields of Bowen's disease from which new invasive cutaneous squamous cell carcinoma (cSCC) can arise, the rate accelerating with age, particularly in the immunosuppressed. These patients can have poor oncological outcomes, but also poor quality of life, with itch, flaking skin and poor cosmesis. They can have comorbidities that can preclude other treatments. The durability of tradition field treatments is disappointing. New radiation techniques especially volumetric modulated arc therapy (VMAT) allow treatments of larger convex fields (eg scalp, forehead, cheeks, forearms, legs) safely. We present our initial cohort of forty fields. Material and Methods Patients with large symptomatic fields of clinical Bowen's disease that had given rise to histologically confirmed cSCC were consented and treated. Radiotherapy metrics were recorded. In vivo dosimetry was performed to ensure that the planned dose was delivered. Acute toxicity, quality of life and oncological outcomes at six months were recorded.