ESTRO 38 Abstract book

S867 ESTRO 38

2 CHRU Besançon, Radiation Oncology, Besançon, France ; 3 Centre Léon Bérard, Surgery, Lyon, France ; 4 Centre Léon Bérard, Medical Oncology, Lyon, France ; 5 Centre Léon Bérard, Pathology, Lyon, France Purpose or Objective To compare outcomes of soft tissue sarcomas (STS) with and without residual disease subsequent to re-excision in our institution after primary unplanned surgery. Material and Methods Between 1996 and 2015, 180 patients with extremities or trunk wall STS were referred to our center after unplanned R1 or R2 surgery for local treatment including re-excision with or without post-operative irradiation. Cutaneous and lipoma-like sarcomas were excluded. Re-excision was considered R0 if margins were ≥ 1 mm and R1 when margins were closer. Re-excision found microscopic residual disease in 93 patients, and no residual disease in 87 patients. Median time between unplanned surgery and re-excision was 2 months (range 1-8). Adjuvant radiotherapy was performed for 133 patients (74%) with a median delivered dose of 50 Grays in 25 fractions. Results Median follow-up was 78 months (range 3-244). Median age was 62 years old. In the group of patients with residual disease (R group), STS were more likely to be of higher grade (p=0.043) and larger volume (p<0.01) than the group of patients without residue (No-R group). Radiotherapy was more frequently performed in R group (74/93 patients) than No-R group (59/87 patients) (p=0.045). In R-group, re-excision was R1 for 65% of patients and R0 for 35%. Achieving R0 margins was associated with better LRFS, MFS, DSS and OS on univariate (p=0.024 for LRFS) and multivariate analysis (p=0.027 for LRFS); grade 3 sarcomas were associated with worse MFS on multivariate analysis (p=0.044). Whether or not residual disease was remaining at the time of re-excision did not impact local-recurrence-free survival (LRFS), which was similar in the 2 groups : 62.4 months in R-group vs 73.4 months in No-R group (p=0.092). In an analogous way, metastasis-free survival (MFS), overall and disease-specific survival (OS and DSS) were not different in the 2 compared groups. In No-R group, radiotherapy was associated with better LRFS on univariate analysis (p=0.014); tendency to better LRFS was observed on multivariate analysis (p=0.08); grade 3 sarcomas had worse MFS on univariate analysis Achieving R0 re-excision after primary unplanned surgery is essential. Our results suggest that radiotherapy should be performed after re-excision even if no residual disease is observed. (p=0.014). Conclusion EP-1609 Volumetric-modulated arc whole-brain radiotherapy prevents permanent alopecia for pediatric patients M. Uto 1 , K. Ogura 2 , K. Umeda 3 , T. Katagiri 4 , K. Takehana 1 , M. Nakamura 1,5 , N. Mukumoto 1 , Y. Miyabe 1 , T. Kamitori 3 , A. Iwai 3 , Y. Arakawa 6 , Y. Mineharu 6 , M. Tanji 6 , I. Kato 3 , H. Hiramatsu 3 , T. Mizowaki 1 1 Kyoto University Graduate School of Medicine, Department of Radiation Oncology and Image-Applied Therapy, Kyoto, Japan ; 2 Kobe City Medical Center General Hospital, Department of Therapeutic Radiology, Kobe, Japan ; 3 Kyoto University Graduate School of Medicine, Department of Pediatrics, Kyoto, Japan ; 4 Shizuoka City Shizuoka Hospital, Department of Radiation Oncology, Shizuoka, Japan ; 5 Kyoto University Graduate School of Medicine, Division of Medical Physics Department of Information Technology and Medical Electronic Poster: Clinical track: Paediatric tumours

Engineering- Human Health Sciences, Kyoto, Japan ; 6 Kyoto University Graduate School of Medicine, Department of Neurosurgery, Kyoto, Japan Purpose or Objective In pediatric patients, permanent alopecia occurred is a grave late complication of multi-drug chemotherapy (CTx) plus cranial irradiation, reducing both patient self-esteem and quality of life. To prevent permanent alopecia, we started to use craniospinal irradiation (CSI) using the volumetric-modulated arc whole-brain radiotherapy (VMAT-WBRT) for pediatric patients, and their hair had fully recovered without disease progression. As the threshold to prevent permanent alopecia is still unknown, we evaluated the dose distribution of VMAT-WBRT and compared the dosimetric parameters between VMAT- WBRT and conventional whole-brain radiotherapy (WBRT). Material and Methods Four consecutive patients (4–11 years old) who received CSI using VMAT-WBRT from June 2015 to December 2016 were included. One patient with embryonic carcinoma received radiotherapy (RT) with concurrent CTx; three patients with medulloblastoma (two patients with standard risk, and one patient with high risk) received RT followed by CTx. The prescribed doses of CSI were 23.4– 35.2 Gy in 13–22 fractions, respectively. 5 mm thickness of the hair follicles bearing scalp was created (Fig. A). VMAT-WBRT was delivered with double arcs, and optimization was performed to reduce doses to the hair follicles with keeping the dose coverage to the planning target volume. For the dosimetric study, the conventional WBRT plans were retrospectively created, and the dose distributions were compared between VMAT-WBRT and conventional WBRT. Doses to the planning target volume for whole brain [PTV(WB)] and organs at risk (OARs), including hair follicles, cochlea, lacrimal glands, lens, eyes, parotid glands, oral cavity, hypopharynx, and thyroid, were evaluated. Results Although all patients experienced temporary alopecia, their hair fully recovered over the whole scalp within 8 months after finishing RT. None had disease progression at least 23.9 months after completing CTx or RT. In the dosimetric study, the mean doses to the hair follicles, parotid glands, and left lacrimal glands were lower in the VMAT-WBRT group. On the other hand, the mean doses to the oral cavity, hypopharynx, and thyroid were higher in the VMAT-WBRT group than in the conventional WBRT group. The average mean equivalent doses in 2-Gy fractions (EQD2) to the hair follicles were 19.5 and 13.3 Gy in the conventional WBRT and VMAT-WBRT groups, respectively. In this study, the mean EQD2 to the hair follicles of all patients who received VMAT-WBRT were lower than 15.1 Gy. The D2 of other OARs and the D2, D98, D50, mean doses, V90, V95, and V107 of PTV(WB) were similar between the two groups.