The impact of reduced-volume, intensity-modulated radiation therapy on disease control in nasopharyngeal carcinoma.

Yu-Wei Lin,Li-Ching Lin,Steve P Lee,Chia-Chun Chen

doi:10.1371/journal.pone.0125283

Abstract

ObjectiveTo investigate the feasibility of using intensity-modulated radiotherapy (IMRT) with reduced, high-dose target volumes for nasopharyngeal carcinoma (NPC).MethodsThe first 57 patients (admitted from October 2005 to May 2008) were treated with large-target-volume IMRT (LV-IMRT). For the LV-IMRT group, the CTV at 70 Gy (CTV70) was delineated as the gross target volume (GTV) plus 7mm, with or without the first-echelon lymph-node region. The next 56 patients (admitted from June 2008 to November 2011) were treated with reduced-target-volume IMRT (RV-IMRT). For the RV-IMRT group, the CTV70 was delineated as the GTV alone.ResultsThe 4-year local recurrence-free, regional recurrence-free, distant metastasis-free, progression-free, and overall survival rates were 77.2%, 80.1%, 83.2%, 61.2%, and 74.4% for the LV-IMRT group and 83.5%, 92.6%, 89.1%, 78.5, and 91.0% for the RV-IMRT group, respectively. Late toxicity scoring of xerostomia was lesser in the RV-IMRT group than the LV-IMRT group (P < 0.001).ConclusionsThe use of RV-IMRT for the treatment of NPC did not negatively affect survival rates but did reduce the late xerostomia events compared to LV-IMRT.

Highlights

Controlling nasopharyngeal carcinoma (NPC) has been a challenge for radiation oncologists, in endemic region
Late toxicity scoring of xerostomia was lesser in the RV-intensity-modulated radiation therapy (IMRT) group than the large-target-volume IMRT (LV-IMRT) group (P < 0.001)
A major breakthrough in NPC treatment has been the development of intensity-modulated radiation therapy (IMRT), and encouraging clinical results involving the use of IMRT to treat NPC have been reported from studies involving single institutions[1,2,3,4,5] as well as from clinical studies performed at multiple centers[6, 7]

Summary

Introduction

Controlling nasopharyngeal carcinoma (NPC) has been a challenge for radiation oncologists, in endemic region. The locoregional control of NPC depends on high-dose radiation therapy; the nasopharyngeal region is surrounding by critical, dose-limiting normal tissue. The local control rate of NPC is greater than 85%, with relatively few marginal failures being reported. The use of high-dose radiation in tissues adjacent to the clinical target volumes (CTVs) for the treatment of potentially subclinical disease is controversial[8,9,10]. Preserving excessive normal tissue, in the parotid gland, can lead to unexpected failures[11]. The purpose of the present study was to investigate the feasibility and efficacy of using IMRT with reduced, high-dose CTVs and reduced, high-dose planning target volumes (PTVs) for the treatment of NPC

Methods

Results

Conclusion