['To confirm that total number of microvessels per tumor area (TN/TA) and total microvessel perimeter per tumor area (TP/TA) are predictors for radiosensitivity in early-stage glottic carcinoma.', 'One hundred twenty consecutive patients with T1-2N0M0 glottic cancer who were treated with radical radiotherapy in three different hospitals in Japan were included in this study. Biopsy specimens from patients were immunostained with anti-CD31 antibody. The TN/TA and TP/TA of each sample were analyzed using a computer-assisted image analysis system. Patients were stratified into high and low groups according to the cut-off values derived from receiver operating characteristic curve analysis. Progression-free survival rates of the different groups were compared. The relationship of microvessel perimeter to vessel maturation was also discussed.', 'Survival analysis showed higher TP/TA to be associated significantly with longer progression-free survival, as compared with the lower-level group (p = 0.031). In multivariate analysis, both TP/TA (p = 0.037) and T stage (p < 0.001) proved to be independent predictive factors. Microvessel perimeter correlated closely with vessel maturity, which suggests that a tumor with high TP/TA contains more functional vessels and as a result contains more oxygenated and radiosensitive cells.'] Is total microvessel perimeter per tumor area a predictor of radiosensitivity in early-stage glottic carcinoma?