ESTRO 36 Abstract Book

S336 ESTRO 36 _______________________________________________________________________________________________

Purpose or Objective Radiotherapy may induce transient or permanent hair loss with a significant psychological impact on patient’s quality of life. Sparing the scalp during focal cranial RT for primary brain cancer is a challenging issue because the scalp is often adjacent to the target and because clear constraints for this structure are not available in the literature. Herein, we report ad-interim results of a prospective clinical study using a scalp sparing technique

VHI had a higher sensitivity for dose inhomogeneities and outperformed traditional indices. Underdosage of WBRT treatment plans as determined by the VHI was associated with decreased overall survival. PO-0642 Influence of Introduction of VMAT and FET- PET on Treatment Outcomes for Glioblastoma Patients P. Munck af Rosenschöld 1 , I. Law 2 , S. Engelholm 1 , A. Muhic 1 , M. Lundemann 1 , H. Roed 1 , K. Grunnet 1 , H. Poulsen 1 1 Rigshospitalet, Department of Oncology, Copenhagen, Denmark 2 Rigshospitalet, Department of Nuclear Medicine, Copenhagen, Denmark Purpose or Objective We sought to assess the influence of the clinical introduction of new radiation therapy technologies on the outcome for glioblastoma patients. Material and Methods Newly diagnosed glioblastoma patients receiving 60 Gy with concomitant and adjuvant temozolomide in the period 2005-2014 were analyzed. Gross tumor volume (GTV) and a clinical target volume by addition of up to 2 cm margin were defined based on MRI. A subset of patients had a biological target volume (BTV) defined based on amino-acid 18 F-FET-PET scanning. The patients’ target volumes were treated using conformal radiation therapy (CRT, N=159) or volumetric modulated arc therapy (VMAT) with hippocampal sparing and daily image-guided radiation therapy (IGRT) (N=322). Progression-free survival (PFS) was assessed using the McDonald criteria. Associations between MGMT status, age at RT, performance status, use of steroids, GTV size, BTV size, tumor dose conformity (GTV D95%), mean brainstem dose, mean brain dose, mean hippocampal dose, as well as use of FET-PET and VMAT, for PFS and overall survival (OS) were explored. Results A total of 521 patients were evaluable, of which 190 patients had FET-PET scanning data. Two patient cases are presented in Fig.1. Average brain dose was lower for patients treated with VMAT compared to CRT (p<0.001, Mann-Whitney). The Kaplan-Meier estimate of PFS (7 months) and OS (15 months) was unaffected by CRT, VMAT and FET-PET technology. Univariate and multivariate Cox regression models for OS are presented in Table 1. Multivariate Cox regression models revealed association of higher mean brainstem dose (p<0.001), BTV (p=0.045), steroid use at baseline (p=0.003), age (p=0.019) and MGMT status (p=0.022) with lower OS. Multivariate Cox models revealed association with increased average brain dose and lower PFS (p<0.001). Conclusion VMAT and IGRT technology treated patients had lower doses to the brain and hippocampi, which may reduce toxicity and preserve cognition. A combination of clinical, imaging and radiation dosimetry metrics provided the best prognostic model for OS. Reducing the mean brain dose for glioblastoma patients could potentially improve PFS and OS. PO-0643 Scalp-sparing radiotherapy to minimize alopecia in patients with primary brain cancer S. Scoccianti 1 , G. Simontacchi 1 , C. Talamonti 2 , L. Marrazzo 2 , G.A. Carta 1 , L. Visani 1 , M. Baki 1 , L. Poggesi 1 , D. Greto 1 , B. Detti 1 , P. Bonomo 1 , M. Loi 1 , S. Pallotta 2 , L. Livi 1 1 Azienda Ospedaliera Universitaria Careggi, Radiotherapy Unit, Florence, Italy 2 Azienda Ospedaliera Universitaria Careggi, Medical Physics Unit, Florence, Italy

in primary brain cancer. Material and Methods

Patients treated with focal radiotherapy for primary brain cancer were included. Factors that may have an impact on alopecia (age, cigarette smoking, use of levetiracetam and chemotherapy) were registered. During the simulation CT a wire was used to indicate the hairline of the patient (figure 1). During the contouring process, the scalp volume was defined as a ring region of interest including the tissue between the skin and the skull. For the inverse planning, primary constraint for the scalp was Dmax≤16 Gy, secondary constraint was Dmax≤25 Gy, tertiary constraint was Dmax≤35 Gy. VMAT plans were generated for a prescription dose of 50-60 Gy in 2-Gy daily fractions. Clinical evaluation was provided at the end of the radiation treatment for assessing the transient alopecia and every 6 months to evaluate the permanent hair loss. During each clinical follow-up evaluation, the patient was asked to wear the thermoplastic mask used during the treatment in order to define with a wire the area of alopecia (figure 2 and 3). Then, a CT scan was performed to the mask and these images are coregistered to the simulation CT to obtain a dosimetric evaluation in the areas of alopecia (figure 4). Alopecia was assessed according to CTCAE version 4.0. Results Meeting the constraints that we had set for the scalp was not always feasible for cortical and subcortical targets. Dose to the scalp was always minimized as much as possible. A total of sixty patients were enrolled. 46 patients were available for the evaluation of acute alopecia. Three out of 46 had no alopecia; G1 and G2 alopecia occurred in 7 and 36 patients, respectively. The risk of acute alopecia was proportional to the dose received by the scalp Dose to the scalp 10 Gy 16 Gy 20 Gy 25 Gy 30 Gy 35 Gy Risk of alopecia 7-31% 45-49% 47-65% 53-74% 55-77% 62-80% 14 patients performed the first trichological follow-up at 6 months: twelve out of 14 (85.7%) completely recovered their alopecia (4 had G1 alopecia, whereas 10 had G2 alopecia when they finished RT). Conclusion Our preliminary results show that risk of acute alopecia is proportional to the dose received by the scalp. Minimizing the dose to the scalp seems to lead a high probability of alopecia recovery after 6 months. These results need to be confirmed with the long-term follow up of all the enrolled patients. Study of the dose distribution in the areas of alopecia will be the base for the definition of reliable constraints both for transient and permanent alopecia PO-0644 Overall survival following stereotactic radiosurgery (SRS) for breast cancer brain metastases H. Patel 1 , S. All 2 , A. Keller 2 , B. Dumas 2 , C. Sherrill 2 , M. Mejia 2 , N. Ramakrishna 3 1 University of Central Florida College of Medicine,