Clinical Outcome for Nasopharyngeal Carcinoma with Predominantly WHO II Histology Treated with Intensity-modulated Radiation Therapy in Non-endemic Region of China

Objectives: To evaluate the clinical outcomes of using intensity-modulated radiotherapy (IMRT) in the primary treatment of nasopharyngeal carcinoma (NPC) in Northwest China, including assessments of failure patterns, toxicities and potential prognostic factors.

Methods And Materials: Between January 2006 and June 2010, 193 newly diagnosed non-metastatic NPCs were treated by IMRT with simultaneous-integrated boost (SIB) technique in Xijing Hospital of Northwest China. Cisplatin-based chemotherapy was offered to 85.5% patients. Acute and late toxicities were graded according to the Radiation Therapy Oncology Group (RTOG) scoring criteria. Prognostic factors were assessed by univariate or multivariate analysis. Statistical analyses were performed on survival and failure patterns.

Results: Median follow-up was 34 months. WHO type II was the predominant histology for NPCs (69.9%) in our study group. Twelve patients experienced local regional failure and total distant metastasis occurred in 34 patients, representing the major mode of failure. The 3-year local recurrence-free (LRFS), regional recurrence-free (RRFS), distant metastasis-free (DMFS) and overall survival (OS) rates were 86.6%, 86.7%, 86.4%, and 85.7%, respectively. Multivariate analyses showed N-classification, age (≤ 50 vs. >50) and WHO type (WHO II vs. WHO III) were independent predictors for DMFS, LRFS and OS. Tumor volume (≤ 50 cm(3) vs. >50 cm(3)) and presence of anemia were independent significant prognostic factors for profession-free survival (PFS). No significant difference was observed between different T categories. Acute and late toxicities were mild or moderate. No grade IV toxicities were observed.

Conclusions: WHO II was the predominant histology and a significant poor prognostic factor in our study group, indicating different carcinogenetic pathways of NPC between endemic and non-endemic regions. Our experience of using IMRT in the treatment of NPC in non-endemic region showed excellent locoregional control and favorable toxicity profiles.