Importance of total radiation dose and overall treatment time in T1 early glottic cancer

Background: In this study, we retrospecvely reviewed the treatment outcome of 63 paents with T1 early gloc cancer treated with RT alone to determine the treatment outcome and the prognosc factors affecng local control. Materials and Methods: All paents were treated by 6 MV photons with convenonal bilateral fields up to a median dose of 66 Gy in 33 fracons. Results: The 5-year local control rate and overall survival were 77.7% and 93.1%, respecvely. The total radiaon dose with a cut-off value of 66 Gy was a significant prognosc factor for local control. The 5-year local control rate was 54.5% in paents treated with less than 66 Gy compared to 85.7% in paents treated with 66 Gy or higher dose (p = 0.014). In subgroup analysis, in paents who received 66 Gy or higher doses, all recurrences developed in whose overall treatment me was 49 days or longer, although the stascal significance was marginal (p = 0.066). Conclusion: This study showed that a total dose of 66 Gy or higher is required for the treatment of T1 gloc cancer, and delivering the total dose within 49 days seems important for local control.