The efficacy and toxicity of individualized intensity-modulated radiotherapy based on the tumor extension patterns of nasopharyngeal carcinoma.

Li Lin,Rui Guo,Lu-Lu Zhang,Yuan Zhang,Fan Zhang,Lin Xu,Ji-Jin Yao,Jun Ma,Ai-Hua Lin,Guan-Qun Zhou,Ying Sun

doi:10.18632/oncotarget.8004

Abstract

BackgroundTo evaluate the efficacy and toxicity of intensity-modulated radiotherapy (IMRT) using individualized clinical target volumes (CTVs) based on the loco-regional extension patterns of nasopharyngeal carcinoma (NPC).MethodsFrom December 2009 to February 2012, 220 patients with histologically-proven, non-disseminated NPC were prospectively treated with IMRT according to an individualized delineation protocol. CTV1 encompassed the gross tumor volume, entire nasopharyngeal mucosa and structures within the pharyngobasilar fascia with a margin. CTV2 encompassed bilateral high risk anatomic sites and downstream anatomic sites adjacent to primary tumor, bilateral retropharyngeal regions, levels II, III and Va, and prophylactic irradiation was gave to one or two levels beyond clinical lymph nodes involvement. Clinical outcomes and toxicities were evaluated.ResultsMedian follow-up was 50.8 (range, 1.3–68.0) months, four-year local relapse-free, regional relapse-free, distant metastasis-free, disease-free and overall survival rates were 94.7%, 97.0%, 91.7%, 87.2% and 91.9%, respectively. Acute severe (≥ grade 3) mucositis, dermatitis and xerostomia were observed in 27.6%, 3.6% and zero patients, respectively. At 1 year, xerostomia was mild, with frequencies of Grade 0, 1, 2 and 3 xerostomia of 27.9%, 63.3%, 8.3% and 0.5%, respectively.ConclusionsIMRT using individualized CTVs provided high rates of local and regional control and a favorable toxicity profile in NPC. Individualized CTV delineation strategy is a promising one that may effectively avoid unnecessary or missed irradiation, and deserve optimization to define more precise individualized CTVs.

Highlights

Nasopharyngeal carcinoma is most endemic in South‐Eastern Asians, with an age‐standardized incidence in male of 20–50/100000 in southern china [1]
The mean dose to planning target volume of nasopharynx (PTVnx) was 72.62 Gray (Gy)
The dose received by 1% of the volume of the planning organ at risk volume (PRV) of the brain stem and spinal cord was 58.64 Gy and 39.87 Gy, respectively

Summary

Introduction

Nasopharyngeal carcinoma is most endemic in South‐Eastern Asians, with an age‐standardized incidence in male of 20–50/100000 in southern china [1]. Radiation therapy is the mainstay treatment modality for non‐metastatic disease. NPC radiation therapy utilizes two‐dimensional conventional treatment (2D‐CRT). Disease control has been acceptable [2,3,4]; high‐dose irradiation has been associated with high probability of toxicities. Intensity modulated radiotherapy (IMRT) is generally accepted as a more advanced radiation technique to improve the therapeutic ratio and encouraging outcomes have been achieved over the past decade [5,6,7,8]. Www.impactjournals.com/oncotarget optimal clinical target volume (CTV) for NPC is far away from determined. To evaluate the efficacy and toxicity of intensity‐modulated radiotherapy (IMRT) using individualized clinical target volumes (CTVs) based on the loco‐regional extension patterns of nasopharyngeal carcinoma (NPC)

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