ESTRO 2022 - Abstract Book

S929

Abstract book

ESTRO 2022

survival (DMFS) and correlated with primary tumor volume. The Kruskal-Wallis and Mann-Whitney test were used for comparison among variables. The Kaplan Meier and hazard model were used for outcome analysis Results At a median follow up 38 months (IQR: 5-103 months), 5 (12.5%) patients developed locoregional failure and 12 (30%) patients were failed at distant sites. The median primary tumor volume of the entire cohort was 84.7cm3 (23-255.3cm3). Although a wide variation in tumor volume was observed within the same as well as different T stage however there was a gradual increase in tumor volume with advancing T stage (p< 0.001), similar finding was also observed in N classification without statistically significance (p=0.467). The 5-year Locoregional failure free survival (LFFS), disease free survival (DSF) and distant metastasis free survival (DMFS) was 87.2%, 74.6% and 64.5% respectively. In order to better estimate the impact of tumor volume on clinical outcomes, tumor volumes were divided into three equal groups < 66cm3, 66-95cm3 and > 95cm3. On analysis N stage showed good relationship with distant metastasis free survival (DMFS) (p < 0.05), T stage on local control (p 0.09), but primary tumor volume was found to have significant correlation with all defined clinical outcomes i.e. LFFS, DFS & DMFS (p < 0.05). Conclusion Primary tumor volume was found to have significant correlation with clinical outcome i.e., locoregional as well distant metastasis in nasopharyngeal carcinoma. S. KASHID 1 , A. Budrukkar 1 , A. Sasidharan 1 , M. Mahimkar 2 , N. Mittal 3 , U. Patel 2 , S. Ghosh-Laskar 1 , V. Murthy 1 , T. Gupta 1 , A. Patil 3 , M. Swain 1 , N. Mummudi 1 , M. Bal 3 , K. Prabhash 4 , A. Joshi 4 , V. Noronha 4 , V. Patil 4 , S. Sinha 1 , A. Kumar 1 , J.P. Agarwal 1 1 Tata Memorial Hospital, Radiation Oncology, Mumbai, India; 2 Advanced Centre for treatment, Research and Education in Cancer, Pathology, Navi Mumbai, India; 3 Tata Memorial Hospital, Pathology, Mumbai, India; 4 Tata Memorial Hospital, Medical Oncology, Mumbai, India Purpose or Objective To evaluate clinical outcomes, prognostic factors and the disease biology of oropharyngeal squamous cell cancer (OPSCC) treated with radiotherapy (RT) with or without concurrent chemotherapy. Materials and Methods Six hundred thirty consecutive patients of OPSCC treated with RT with or without concurrent chemotherapy in a tertiary care centre from January 2013 to December 2017 were analysed to study various patient, disease and treatment related factors affecting the clinical outcomes. Descriptive analysis was used for demographics, Kaplan Meir method was used for survival analysis, Log rank test was used for univariate analysis (UVA) and Cox regression method was used for multivariate analysis (MVA). Results The median age at presentation was 56 years. Five hundred forty three (86.1%) patients were of locally advanced stage. HPV status was known for 297 patients of which 37(12.5%) tested p16 positive and 260(87.5%) were p16 negative. Chemo- radiotherapy was offered to 441(70%) patients. Intensity modulated radiotherapy (IMRT) technique was used for 163 (25.9%) patients. At median follow up for surviving patients of 54 months (IQR 37.7-68.3months) 5 year overall survival (OS), local control(LC), loco-regional control(LRC), disease free survival(DFS) were 37.1%, 48.3%, 36.1% & 30.9% respectively. At 5 year LC & LRC for stage I, II, III & IV were 62.5% & 62.5%, 58.9% & 53%, 55.7% & 45.5% and 43.4% & 29% respectively. Stage wise 5 year OS & DFS for stage I, II, III & IV were 58% & 62.5%, 54.3% & 44%, 49.2% & 43.8%, 30% & 23.6% respectively. HPV positive cohort showed significantly better outcomes with 5 year LC, LRC, DFS, OS was 84.6% vs 42.8% (p <0.001), 67.5% vs 29.4% ( p<0.001), 59.4% vs 25.8% (p <0.001), 62.6% vs 36.4% (p 0.004) in HPV positive and HPV negative cohort respectively. On UVA & MVA T1-T2 stage (AJCC 7 th ed.), early group stage (AJCC 7 th ed.), concurrent chemotherapy use, IMRT technique and radiotherapy dose >66Gy had statistically significant improvement for LC, LRC, DFS and OS. Conclusion HPV positivity was very low (12.5%) in our cohort of patients. HPV positive patients had significantly better clinical outcomes as compared to HPV negative OPSCC. In addition T stage, group stage, concurrent chemotherapy use, technique of RT, RT doses >66Gy were independent prognostic factors. PO-1094 Long term outcomes of 630 consecutive patients of oropharyngeal cancer treated with radiotherapy

PO-1095 pre-treatment salivary flow predicts recovery of salivary flow after IMRT for head and neck cancer

S. Hiraoka 1 , A. Nakajima 1 , M. Yoshimura 1 , T. Mizowaki 1

1 Graduate School of Medicine, Kyoto University, Department of Radiation Oncology and Image-Applied Therapy, Kyoto, Japan Purpose or Objective Xerostomia is one of the most significant adverse events caused by radiotherapy and severely reduces patients' quality of life for a lengthy period in patients with head and neck cancer. Intensity-modulated radiation therapy (IMRT) reduces the incidence of xerostomia compared to conventional radiotherapy. However, most patients experience temporary severe