Change in olfaction after radiotherapy for nasopharyngeal cancer--a prospective study.
OBJECTIVE
To evaluate the changes in olfactory function in patients with nasopharyngeal carcinoma who have received radiation to the head and neck.


METHODS
Olfactory function of consecutive patients with nasopharyngeal carcinoma was assessed prospectively before irradiation and serially up to 1 year after radiotherapy by the Sniffin' Sticks (Erlangen, Germany) olfactory function test and by a patient symptom visual analogue scale.


RESULTS
Fifty-eight patients were recruited before radiotherapy was commenced. Three patients could not give a reliable response to the Sniffin' Sticks test even in this first assessment, and 7 patients did not return for evaluation after irradiation. Forty-eight patients were available for follow-up assessment. Mean olfactory threshold scores by the Sniffin' Sticks test were found to deteriorate significantly at 12 months when compared with the scores before irradiation (8.3 at 12 months vs 11.5 before irradiation; P =.001). Scores for olfactory discrimination and for identification did not exhibit any significant changes when assessed at 12 months (P >.05 for both). Subjective patient assessment of olfactory function with the visual analogue scale at 12 months did not demonstrate any significant differences when compared with patients' assessment before irradiation (P =.90). An increase in discharge was the only nasal symptom that demonstrated a significant change at 12 months when compared with the assessment before irradiation (P < 001).


CONCLUSIONS
Deterioration in olfactory threshold scores was found at 12 months after irradiation and was not noticed by the patients.
Ho
Wai-kuen
WK
Division of Otorhinolaryngology-Head & Neck Surgery, Department of Surgery, University of Hong Kong Medical Center, Queen Mary Hospital, Pokfulam, Hong Kong, PR China.
Kwong
Dora L W
DL
Wei
William I
WI
Sham
Jonathan S T
JS
D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000503:physiopathology / Q000532:radiotherapy*; D011446:Prospective Studies; D012647:Self-Assessment; D012903:Smell / Q000502:physiology*