Intensity-modulated radiotherapy of head and neck cancer aiming to reduce dysphagia: early dose-effect relationships for the swallowing structures.
OBJECTIVE
To present initial results of a clinical trial of intensity-modulated radiotherapy (IMRT) aiming to spare the swallowing structures whose dysfunction after chemoradiation is a likely cause of dysphagia and aspiration, without compromising target doses.


METHODS
This was a prospective, longitudinal study of 36 patients with Stage III-IV oropharyngeal (31) or nasopharyngeal (5) cancer. Definitive chemo-IMRT spared salivary glands and swallowing structures: pharyngeal constrictors (PC), glottic and supraglottic larynx (GSL), and esophagus. Lateral but not medial retropharyngeal nodes were considered at risk. Dysphagia endpoints included objective swallowing dysfunction (videofluoroscopy), and both patient-reported and observer-rated scores. Correlations between doses and changes in these endpoints from pre-therapy to 3 months after therapy were assessed.


RESULTS
Significant correlations were observed between videofluoroscopy-based aspirations and the mean doses to the PC and GSL, as well as the partial volumes of these structures receiving 50-65 Gy; the highest correlations were associated with doses to the superior PC (p = 0.005). All patients with aspirations received mean PC doses >60 Gy or PC V(65) >50%, and GSL V(50) >50%. Reduced laryngeal elevation and epiglottic inversion were correlated with mean PC and GSL doses (p < 0.01). All 3 patients with strictures had PC V(70) >50%. Worsening patient-reported liquid swallowing was correlated with mean PC (p = 0.05) and esophageal (p = 0.02) doses. Only mean PC doses were correlated with worsening patient-reported solid swallowing (p = 0.04) and observer-rated swallowing scores (p = 0.04).


CONCLUSIONS
These dose-volume-effect relationships provide initial IMRT optimization goals and motivate further efforts to reduce swallowing structures doses to reduce dysphagia and aspiration.
Feng
Felix Y
FY
Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109-0010, USA.
Kim
Hyungjin M
HM
Lyden
Teresa H
TH
Haxer
Marc J
MJ
Feng
Mary
M
Worden
Frank P
FP
Chepeha
Douglas B
DB
Eisbruch
Avraham
A
D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D003679:Deglutition / Q000528:radiation effects; D003680:Deglutition Disorders / Q000209:etiology / Q000517:prevention & control*; D004947:Esophagus / Q000528:radiation effects; D005260:Female; D006801:Humans; D007013:Hypopharynx / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy / Q000532:radiotherapy*; D009959:Oropharyngeal Neoplasms / Q000188:drug therapy / Q000532:radiotherapy*; D011788:Quality of Life; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D011795:Surveys and Questionnaires