Prognostic factors for local control in patients receiving radiation therapy for early glottic cancer: anterior commissure involvement and effect of chemoradiotherapy.

To assess the prognostic factors for local control in patients with early glottic cancer, we retrospectively analyzed the data of 130 consecutive patients who were treated by definitive radiation therapy (RT) or concurrent chemoradiotherapy (CRT) for early glottic squamous cell carcinoma (UICC sixth edition T1N0M0 and T2N0M0) at Kanagawa cancer center between 1999 and 2011. There were 63 patients with T1 cancer and 67 patients with T2 cancer. Twenty-one patients with T2 tumors were treated by chemoradiotherapy (CRT). The median follow-up period was 73 months (range, 22-165 months). The 5-year local control (LC) rate in all patients was 81 %. The 5-year LC rates in the patients with T1 and T2 cancer were 89 and 74 %, respectively. Univariate analysis showed that a higher T stage (T2) (p = 0.0301), anterior commissure involvement (p < 0.000001), and habitual drinking (p = 0.054) were correlated with decreased local control rate. Multivariate analysis identified only anterior commissure involvement as a significant prognostic factor for local control (LC rate 91 vs. 51 %, risk ratio 5.3, 95 % CI 2.3-12, p < 0.001). In the patients with T2 cancer, there was no statistically significant difference in the LC rate between patients who received RT alone and those who received CRT (RT alone 76 % vs. CRT 67 %; p = 0.832). The findings of this study suggest that anterior commissure involvement is a significant factor influencing the prospect of local control. CRT was not found to be effective for T2 patients in this study.