Dosimetric predictors of xerostomia for head-and-neck cancer patients treated with the smart (simultaneous modulated accelerated radiation therapy) boost technique.
OBJECTIVE
To evaluate the predictors of xerostomia in the treatment of head-and-neck cancers treated with intensity-modulated radiation therapy (IMRT), using the simultaneous modulated accelerated radiation therapy (SMART) boost technique. Dosimetric parameters of the parotid glands are correlated to subjective salivary gland function.


METHODS
Between January 1996 and June 2000, 30 patients with at least 6 months follow-up were evaluated for subjective xerostomia after being treated definitively for head-and-neck cancer with the SMART boost technique. Threshold limits for the ipsilateral and contralateral parotid glands were 35 Gy and 25 Gy, respectively. Dosimetric parameters to the parotid glands were evaluated. The median follow-up time was 38.5 months (mean 39.9 months). The results of the dosimetric parameters and questionnaire were statistically correlated.


RESULTS
Xerostomia was assessed with a 10-question subjective salivary gland function questionnaire. The salivary gland function questionnaire (questions 1, 2, 3, 4, 6, and 9) correlated significantly with the dosimetric parameters (mean and maximum doses and volume and percent above tolerance) of the parotid glands. These questions related to overall comfort, eating, and abnormal taste. Questions related to thirst, difficulty with speech or sleep, and the need to carry water daily did not correlate statistically with the dosimetric parameters of the parotid glands.


CONCLUSIONS
Questions regarding overall comfort, eating, and abnormal taste correlated significantly with the dosimetric parameters of the parotid glands. Questions related to thirst, difficulty with speech or sleep, and the need to carry water daily did not correlate statistically with the dosimetric parameters of the parotid glands. Dosimetric sparing of the parotid glands improved subjective xerostomia. IMRT in the treatment of head-and-neck cancer can be exploited to preserve the parotid glands and decrease xerostomia. This is feasible even with an accelerated treatment regimen like the SMART boost. More patients need to be evaluated using IMRT to identify relevant dosimetric parameters.
Amosson
Chad M
CM
Department of Radiology/Section of Radiation Oncology, Baylor College of Medicine and The Methodist Hospital, Houston, TX 77030, USA.
Teh
Bin S
BS
Van
T John
TJ
Uy
Nathan
N
Huang
Eugene
E
Mai
Wei-Yuan
WY
Frolov
Anna
A
Woo
Shiao Y
SY
Chiu
J Kam
JK
Carpenter
L Steven
LS
Lu
Hsin H
HH
Grant
Walter H
WH
Butler
E Brian
EB
D000328:Adult; D000368:Aged; D003680:Deglutition Disorders / Q000209:etiology; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D004408:Dysgeusia / Q000209:etiology; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D020714:Maximum Tolerated Dose; D008875:Middle Aged; D010306:Parotid Gland / Q000293:injuries / Q000528:radiation effects*; D010342:Patient Acceptance of Health Care; D011832:Radiation Injuries / Q000209:etiology*; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D012189:Retrospective Studies; D012472:Salivation / Q000528:radiation effects; D012893:Sleep Wake Disorders / Q000209:etiology; D013064:Speech Disorders / Q000209:etiology; D011795:Surveys and Questionnaires; D013894:Thirst; D014057:Tomography, X-Ray Computed; D014987:Xerostomia / Q000209:etiology*