ESTRO 38 Abstract book

S636 ESTRO 38

collected retrospectively. Pretreatment biopsy formalin- fixed paraffin-embedded tumor blocks were used for reevaluation in terms of related immune markers. Totally 44 patients were evaluated for this analysis. Pretreatment HIF-1a and Ki-67 expressions, clinicopathologic data, and tumor volume were analyzed and compared with treatment outcomes. Results Median age was 56 (range, 25-79), and 39% of them were female. Patient characteristics are shown in table 1. The median follow-up duration for all patients and surviving patients was 22.5 months (range, 4-213 months) and 93.0 months (range, 14-213 months), respectively. Ten patients (23%) developed distant metastases, and 15 (34%) had local/locoregional failure. At the time of the last follow- up, 11 patients (25%) were alive. Only 5 patients had p16 positivity, others had p16 (-) tumors. We could not find any significant effect of p16 status over treatment outcome. Median overall survival (OS), locoregional recurrence-free survival (LRFS), and metastasis-free survival (MFS) times were 24.5, 22, and 22.5 months, respectively. Two-years OS, LRFS, and MFS rates were 52%, 64%, and 75%, respectively. Ten of 44 tumor specimens were HIF-1α-negative with a significantly better 5-year survival (92 ± 8%) versus 34 patients who were HIF-1α-positive (45 ± 10%; p < 0.02). patients with hemoglobin levels <12 g/dl showed elevated HIF-1α expression compared to patients with hemoglobin levels ≥12 g/dl (p=0.02). Additionally, HIF-1α correlated with Ki- 67 proliferation marker (p = 0.01). Conclusion This is the first study to evaluate specifically at T3-4 HPSCC for a relationship between hypoxia-associated marker expression and clinical treatment outcomes. Pretreatment immunohistochemical HIF1a and Ki67 expression are adverse prognostic factors for LRFS and OS, indicating HIF-1a and Ki-67 expressions may show a more treatment resistant tumor type. However, we could not give p16 as a prognostic marker T3-4 HPSCC. EP-1147 Local control rate in patients with skull-base chondrosarcoma treated with particle therapy E. D'Ippolito 1 , A. Iannalfi 1 , B. Vischioni 1 , V. Vitolo 1 , M.R. Fiore 1 , S. Ronchi 1 , M. Bonora 1 , A. Barcellini 1 , R. Petrucci 1 , A. Mirandola 1 , A. Vai 1 , E. Mastella 1 , G. Viselner 2 , M. Ciocca 1 , L. Preda 2 , F. Valvo 1 , R. Orecchia 1,3 1 National Center of Oncological Hadrontherapy, Radiotherapy Unit, Pavia, Italy ; 2 National Center of Oncological Hadrontherapy, Diagnostic Image Unit, Pavia, Italy ; 3 European Institute of Oncology, Radiation therapy Unit, Milan, Italy Purpose or Objective Chondrosarcoma is a rare bone tumor that arise from the cartilage. Skull-base location is reported in about 6% of cases. The therapeutic approach to chondrosarcoma of the skull-base is still controversial and clinical experience is limited because of the relative rarity of this tumor. The aim of the study was to assess the local failure rate and overall survival (OS) of patients treated with particle therapy (Proton therapy –PT and Carbon Ion radiotherapy -CIRT) after maximal surgery or in the exclusive setting. Material and Methods between September 2011 to May 2017 35 patients (pts) (17 male, 18 female) with a median age of 45 years (range, 13-78) with histologically proven skull-base chondrosarcoma were treated with PT or CIRT at National Center of Oncological Hadrontherapy (CNAO). 17 pts (49%) underwent previous surgery. A total of 13 pts had grade I (well differentiated), 20 pts had grade II (moderately differentiated) and 2 pts had grade III (poorly differentiated) chondrosarcoma. 6 pts had brainstem involvement, 1 pts optic pathway involvement. 17 pts were treated with CIRT, 18 pts with PT. Median gross tumor volume (GTV) was 16,4 cm 3 (range, 1,64 – 28,28).

0.38) and CT number change (Fig. 2, R = 0.45).

Conclusion The volume and CT number of the parotid glands decreased as a function of the median dose to the parotid glands but were not significantly related to the grade of xerostomia. Further investigation is needed to determine if these changes would predict moderate-to-severe xerostomia and if adaptive radiotherapy could reduce acute and late toxicities. EP-1146 Prognostic Value of Hypoxia for Locally Advanced Hypopharynx Squamous Cell Carcinoma F. Sert 1 , G. Serin 2 , A. Veral 2 , M. Esassolak 1 1 Ege University Medical School&Hospital, Radiation Oncology, Izmir, Turkey ; 2 Ege University Medical School&Hospital, Pathology, Izmir, Turkey Purpose or Objective Head and neck squamous cell carcinoma (HNSCC) is the 6th common malignancy worldwide. As one of HNSCC, hypopharyngeal squamous cell carcinoma (HPSCC) only constitutes approximately 3-5% of HNSCC, but it is usually diagnosed in the advanced stage with poor treatment outcome. In the past decades, different treatment options, including surgery, chemotherapy (CT), radiotherapy (RT), and immunotherapy, have been developed and utilized for HPSCC, but any of those options could not achieve a promising results and the survival rate has not been improved significantly. We should both investigate and understand the resistance mechanisms of this group of patients in order to obtain more promising treatment outcomes. We aim to compare the relationship between the expression of hypoxia-associated marker HIF- 1a and proliferation with Ki-67 and clinical outcome after definitive CRT for locoregionally advanced p16 (-) HPSCC Material and Methods Between January 2005 and December 2016, patients diagnosed with T3-4 HPSCC treated with curative intent by (chemo)radiation were identified using the radiation therapy. Clinicopathologic and outcomes data were