Abstract Book

S643

ESTRO 37

Oncology, Wroclaw, Poland 3 Lower Silesian Oncology Center, Radiotherapy Department, Wroclaw, Poland 4 Lower Silesian Oncology Center, Clinic of Radiation Oncology, Wroclaw, Poland 5 Wroclaw Medical University, Department of Pathomorphology and Oncological Cytology, Wroclaw, Poland Purpose or Objective PTPN14 (Tyrosine-protein phosphatase non-receptor type 14) regulates many processes, including metabolism, cell growth and differentiation. Published studies suggest a role of PTPN14 in the regulation adhesive properties of the cell and the cytoskeleton and the suppression YAP (YAP1 /yes-associated protein 1), the key oncoprotein Hippo pathway that controls the development of organs by regulation of cell proliferation and apoptosis. The aim of the study was to evaluate the effect of PTPN14 protein expression on the prognosis of patients with squamous cell carcinoma of the oral cavity (OCC). Material and Methods The study included 129 Lower Silesian Oncology Center patients, irradiated after radical resection with lymphadenectomy due to squamous cell carcinoma of mouth floor (C04) or mobile part of tongue (C02). The average age of the patients was 55 years (23-77 years). According to the TNM classification (7 th Ed. 2010) in Stage II were diagnosed 30%, III - 29% and IVa - 41% of patients. 50- 68 Gy (mean dose - 60 Gy) of radiotherapy was administered to the region of tumor bed and regional lymphatic drainage. During the 5 years of observation, 37 (29%) of the patients had recurrences, 13 were diagnosed with second malignant tumor, 19 died from causes other than cancer. For immunohistochemistry, anti-PTPN14: Clone 448701 monoclonal antibody was used; Code MAB 4458; R & D systems, 1: 200 dilution. Expression of PTPN14 was cytoplasmatic. Results We found a positive correlation between PTPN14 expression and MCM7 proliferation marker (r s 0.22, p 0.009). This result indicates that PTPN14 expression in tumor cells may be associated with a more malignant phenotype and worse prognosis. Patients whose tumors express PTPN14 in ≥ 75% of cancer cells had a 3-fold higher risk of locoregional relapse, 5 years of locoregional recurrence-free survival (LRFS) was 78% for patients with PTPN14 <75% and 45% for PTPN14≥75% (p = 0.017) (Fig. 1), for disease-free survival (DFS) 71% and 45% (0.069) (Fig. 2). In the analysis of a subgroup of 60 patients with tumor pT1-2 it was found that high expression of PTNP14 is associated with significant shortening of LRFS (p = 0.0063), DFS (p = 0.0546), disease specific survival (DSS) (p = 0.0533). Expression of PTPN14 did not significantly influence the survival of patients with pT3-4 stages. Fig. 1 - Kaplan-Meier comparison of LRFS for patients with PTPN14 expression in ≤75% and> 75% of tumor cells (log-rank p = 0.017).

Conclusion Our study highlights that PTPN14 could be a potential prognostic factor for OCC, especially in low stage of disease (pT1-2). This results should be confirmed in subsequent studies, especially according to our knowlege this study was the first one evaluating impact of PTPN14 on survival of patients with OCC. EP-1145 Does Carcinoma Tongue Differ From Gingivobuccal Sulcus? Analysis of Clinicopathology and Outcomes A. Manickam 1 , C. Nallathambi 2 , R. Sharan 1 , K. Manikantan 1 , S. Chatterjee 2 , I. Mallick 2 , P. Roy 3 , M.A.L. Zameer 3 , I. Arun 3 , A. Pattetheyil 1 1 Tata Medical Centre, Department of Head and Neck Surgery, Kolkata, India 2 Tata Medical Centre, Department of Radiation Oncology, Kolkata, India 3 Tata Medical Centre, Department of Oncopathology, Kolkata, India Purpose or Objective Oral tongue (OT) and gingivobuccal sulcus (GBS) cancers are considered to have varied clinical behaviour. While many consider OT to have an aggressive course and poorer prognosis, conflicting reports show that outcomes are comparable. We have compared the clinicopathologic variables and outcomes among these two sites of oral cavity cancer. Material and Methods Medical records of patients treated for oral cavity cancer between May 2011 and December 2014 in our hospital were examined. All patients who underwent radical surgery with or without adjuvant treatment (RT/CTRT) for OT and GBS cancers were included in the analysis. Adjuvant radiation was given using 3DCRT/VMAT/Helical TomoTherapy and concurrent cisplatin was added for fit and close or involved margins/extra-capsular extension (ECE) positive patients. Standard clinicopathologic factors and follow-up data along with events were noted. Chi-square test was used to determine any significant difference in variables between the groups. Survival was analysed using Kaplan-Meier method and log-rank test was used to determine significance. Cox regression was done to identify factors that affected survival and hazard ratios along with confidence intervals are reported. p- value<0.05 is considered statistically significant. Results Three-hundred and eleven patients were included (144 OT and 167 GBS) with a median follow-up of 20.5 months (IQR: 10-29.8). Median age was 54 years. Male sex, tumor size, tumor thickness, underlying bone involvement and masticator space involvement were significantly higher in GBS whereas perineural involvement (PNI) was significantly commoner in OT. Three-year overall survival (OS), disease-free survival (DFS), locoregional failure-free survival (LRFFS) rates in OT were 91.4%, 69.3% and 77.3% respectively. Three-year OS, DFS and LRFFS rates in GBS were 83.6%, 68.9% and 70.4% respectively and these did not vary significantly with OT (p-value - 0.119, 0.652, 0.117 respectively). Isolated nodal failures and distant

Fig. 2 - Kaplan-Meier comparison of DFS for patients with PTPN14 expression in ≤75% and> 75% of tumor cells (log- rank p = 0.069).