Intensity-modulated radiotherapy for nasopharyngeal carcinoma: clinical correlation of dose to the pharyngo-esophageal axis and dysphagia.
OBJECTIVE
The aim of this study was to quantify the dose delivered to the pharyngo-esophageal axis using different intensity-modulated radiation therapy (IMRT) techniques for treatment of nasopharyngeal carcinoma and to correlate this with acute swallowing toxicity.


METHODS
The study population consisted of 28 patients treated with IMRT between February 2002 and August 2005: 20 with whole field IMRT (WF-IMRT) and 8 with IMRT fields junctioned with an anterior neck field with central shielding (j-IMRT). Dose to the pharyngo-esophageal axis was measured using dose-volume histograms. Acute swallowing toxicity was assessed by review of dysphagia grade during treatment and enteral feeding requirements.


RESULTS
The mean pharyngo-esophageal dose was 55.2 Gy in the WF-IMRT group and 27.2 Gy in the j-IMRT group, p < 0.001. Ninety-five percent (19/20) of the WF-IMRT group developed Grade 3 dysphagia compared with 62.5% (5/8) of the j-IMRT group, p = 0.06. Feeding tube duration was a median of 38 days for the WF-IMRT group compared with 6 days for the j-IMRT group, p = 0.04.


CONCLUSIONS
Clinical vigilance must be maintained when introducing new technology to ensure that unanticipated adverse effects do not result. Although newer planning systems can reduce the dose to the pharyngo-esophageal axis with WF-IMRT, the j-IMRT technique is preferred at least in patients with no gross disease in the lower neck.
Fua
Tsien F
TF
Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia. tsien-fei.fua@petermac.org
Corry
June
J
Milner
Alvin D
AD
Cramb
Jim
J
Walsham
Sue F
SF
Peters
Lester J
LJ
D000208:Acute Disease; D000328:Adult; D000368:Aged; D003680:Deglutition Disorders / Q000209:etiology*; D004750:Enteral Nutrition / Q000706:statistics & numerical data; D004947:Esophagus / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D010614:Pharynx / Q000528:radiation effects*; D011829:Radiation Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome; D015431:Weight Loss