Factors affecting voice quality in early glottic cancer before and after radiotherapy

Background. Radiotherapy (RT) is a successful mode of treatment for early glottic cancer. The aim of the study was to assess voice quality both before and 3 months after successful RT using multimodal methods while also identifying the factors affecting it. Patients and methods. In 50 patients with T1 glottic carcinoma, the subjective (patients' assessment of voice quality [VAS], Voice Handicap Index [VHI] questionnaire, phoniatricians' assessment using the grade/roughness/breathiness [GRB] scale), and objective assessments (fundamental laryngeal frequency [F-0], jitter, shimmer, maximum phonation time [MPT]) of voice quality were performed before RT and 3 months post-RT. The data on gender, age, extent of the tumors, biopsy types, smoking, local findings, and RT were obtained from the medical documentation. Results. Three months after the treatment, VAS, VHI, G and R scores, F-0, and MPT significantly improved in comparison with their assessment prior to treatment. Before the treatment, the involvement of the anterior commissure significantly deteriorated jitter (p = 0.044) and the involvement of both vocal folds deteriorated jitter (p = 0.003) and shimmer (p = 0.007). After the RT, F-0 was significantly higher in the patients with repeated biopsy than in the others (p = 0.047). In patients with post-RT changes, the B score was significantly higher than in those without post-RT changes (p = 0.029). Conclusions. Voice quality already significantly improved three months after the treatment of glottic cancer. The main reason for the decreased voice quality prior to treatment is the tumor's extent. Post-RT laryngeal changes and repeated biopsies caused more scarring on vocal folds adversely influencing voice quality after the treatment.