Factors affecting oncological outcomes
We performed multivariate analysis with Cox models to identify factors associated with OS and 5-year DFS (Table 4). This analysis of multiple factors (gender, age, smoking, alcohol abuse, clinical T stage, surgery pattern, involvement of anterior commissure, and resection margins) indicated that only type of surgery had a significant impact on 5-year DFS (P = 0.02; HR: 6.35, 95% CI: 1.31 to 30.74). Involvement of the anterior commissure had no significant impact on outcome.