Voice quality after radiation therapy for early glottic cancer

Objective: To evaluate the voices of irradiated patients with early glottic carcinoma and to compare these with the voices of healthy volunteers. Design: Case-control study. Setting: University Department of Otorhinolaryngology and Cervicofacial Surgery, University of Ljubljana, Ljubljana, Slovenia. Subjects and Methods: The voice samples (sustained vowel) of 50 patients (44 men and 6 women) who had been irradiated for T1 (43 subjects) or T2 (7 subjects) glottic squamous carcinoma at least 1 year prior to the study were analyzed with the Multi-Dimensional Voice Program (Kay Elemetrics Corp, Lincoln Park, NJ) and compared with those of a normal group of 50 and sex-matched volunteers. Average fundamental frequency, jitter, shimmer, noise-to-harmonic ratio, and degree of voiceless elements were determined. In the irradiated group, videostroboscopy was performed. The patients assessed their voice fatigue. Results: The irradiated subjects demonstrated significantly higher values for jitter, shimmer, and degree of voiceless elements than did the healthy volunteers. The values for noise-to-harmonic ratio were higher in the irradiated group, but the difference was not significant (P=.08). The values for fundamental frequency were almost equal in both groups. In most of the irradiated subjects, some irregularities of the vocal fold vibration were noticed. Many of these patients also reported voice fatigue. Conclusions: Radiation therapy for early glottic cancer results in poorer voice quality compared with normal age- and sex-matched speakers. In most of the irradiated patients, greater than normal effort in voice production was found based on patient assessment. This may result from stiffness of the vibratory source and inadequate compensatory maneuvers in phonation. We suggest that voice therapy during and after radiation therapy may result in better voice quality.