Forty-seven patients with advanced larynx/hypopharynx, nasopharynx or oropharynx/oral cavity cancer were recorded before, and 10 weeks after concomitant chemoradiotherapy (CCRT), to investigate the effect of the tumor versus the effects of treatment. To evaluate voice functioning before and after treatment, voice quality and glottal behavior of sustained /a/ vowels were analyzed acoustically and compared with patient-based data on cigarette and alcohol usage. Acoustic measures of effort, nasality and regularity, such as periodicity or harmonics-to-noise ratio, differed significantly and progressed differently in dependence of the 3 distinct cancer/radiation sites. Baseline measures of voice stability correlated significantly with alcohol/smoking behavior.