Patterns of failure and survival in patients with nasopharyngeal carcinoma treated with intensity-modulated radiation therapy in Saudi Arabia

e295 Background: We aimed to investigate the patterns of failure (locoregional and distant metastasis), associated factors, treatment outcomes in nasopharyngeal carcinoma (NPC) patients treated with intensity modulated radiation therapy (IMRT) combined with chemotherapy, results of reirradiation in recurrent cases and its toxicity. METHODS From April 2006 to December 2011, 68 NPC patients were treated with IMRT and chemotherapy at our hospital. Median radiation doses delivered to gross tumor volume (GTV) and positive neck nodes were 66-70 Gy/33-35fractions. For recurrent cases reirradiation was given by SRS 25 -30 Gy/5 fractions or IMRT 50-60 Gy/25-30 fractions according to volume of recurrence and surrounding critical structures. The clinical toxicities, patterns of failures, locoregional control (LRC), distant metastasis control (DMC), disease free survival (DFS) and overall survival (OS) were observed. RESULTS The median follow up time was 52.2 months (range: 11-87). EBV infection positive was 63.2%.There were 7 locoregional recurrences, 3 regional recurrences with distant metastases and 11 distant metastases. The median interval from the date of diagnosis to failure was 26.5 months (range, 16-50 months). 6/10 (60%) locoregional recurrences were treated with re-irradiation +/- concurrent chemotherapy. Acute grade 3 and 4 mucositis were observed in 2 patients (28.6%); however no significant late toxicities were seen after reirradiation. Nodal recurrences were salvaged by neck dissection. The 5-year LRC, DMC, DFS and OS rates of whole cohort were 81.1%, 74.3%, 60.1% and 73.4% respectively. Cox regression analyses revealed that neoadjuvant chemotherapy, age and Epstein-Barr virus (EBV) were independent predictors for DFS. CONCLUSIONS Distant metastasis is the most common pattern of failure after IMRT with SIB technique with or without neoadjuvant and concurrent chemotherapy in Saudi patients with NPC. Early detection of local and locoregional recurrences is important as reirradiation with IMRT or SRT with or without chemotherapy is still feasible option with acceptable toxicity. However, efforts should be made for proper patient selection.