Impact of Reduced-volume Intensity Modulated Radiation Therapy on Disease Control for Nasopharyngeal Carcinoma

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 lymphnode 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.

Pathologic study of tumour extension for clinically localized unilateral nasopharyngeal carcinoma: Should the contralateral side be included in the clinical target volume?

“…2) to minimize unnecessary radiation doses to normal tissue without interfering with the treatment outcomes. 12 This finding further confirmed the feasibility of IMRT with reduced CTV for the lateralized tumours of NPC patients. They found that no patients suffered recurrence after a median follow-up time of 33 months.…”

“…This finding can be verified by the excellent local control achieved in NPC patients treated with reduced CTV of IMRT compared with the IMRT plans per the current guidelines, and marginal or outside-field failure was uncommon with reduced 12,21 Some oncologists even suggested that the margin expansion from the GTV to the CTV could be omitted, 22 considering the rapid development of technologies in both diagnostic imaging and radiation therapy over the past decades which have improved the accuracy of gross tumour delineation and targeting. In this study, we used biopsy of several sites of the nasopharynx and found that most patients with clinically diagnosed unilateral cancer of the nasopharynx can be confirmed by pathological biopsy.…”

Dosimetric comparison between RapidArc and HyperArc techniques in salvage stereotactic body radiation therapy for recurrent nasopharyngeal carcinoma

“…The initial primary radiation therapy plan was generated as previously described [11]. In short, the planning target volume (PTV) was extended 0 to 3 mm from the clinical target volume (CTV).…”

“…Radiation therapy with or without concurrent chemotherapy represents the standard treatment for nasopharyngeal cancer (NPC) and leads to a 5-year local control rate of greater than 85% [1][2][3][4][5][6][7][8][9]. However, local recurrence still represents a major source of morbidity and mortality in patients with advanced stage NPC [10,11]. Because of the invasive nature of the malignancy which may involve many critical tissues at skull base, radiation therapy often remains to be the main salvage treatment modality once the disease recurs locally.…”

The ratio of weight loss to planning target volume significantly impacts setup errors in nasopharyngeal cancer patients undergoing helical tomotherapy with daily megavoltage computed tomography

“…Size of the PTV can be a crude predictor of acute RT toxicity. 31, 32 However, we found that patients with larger PTV actually had smaller setup errors in the SI and AP directions. Our image guidance procedure allows the observers to apply additional shifts to ensure adequate target coverage following automatic correction of setup displacements.…”