Impact of anterior commissure involvement on recurrence in early-stage vocal cord tumors: a propensity score analysis.

Abstract

Background: Laryngeal cancer is one of the most common head and neck tumors, with 75% affecting the vocal cords. The 8th edition of the TNM staging system defines T1 glottic tumors as those limited to the vocal cords with preserved mobility. Since the publication of the third edition in 1998, this category has been divided into T1a (tumor limited to one vocal cord) and T1b (both vocal cords involved). However, these tumors can also involve the anterior commissure. The anterior commissure is considered a sublocation by the American Joint Committee on Cancer (AJCC) and the Union for International Cancer Control, but it is not accounted for in the current T staging system. Although the anterior commissure is rarely the primary site of glottic tumors (1%), 20% of glottic tumors show involvement of the anterior commissure, with its impact on prognosis still controversial.

Methods: A global and specific survival analysis was performed using the Kaplan-Meier method, comparing survival curves with the Log Rank test. A Cox regression model was constructed, including confounding variables and examining possible interaction terms, evaluating the proportionality assumption through graphical methods. Confounding variables were controlled using the Propensity Score (PS), estimating the effect with different PS methods.

Results: The variable "Anterior Commissure" showed a significant effect on the recurrence of glottic cancer, consistent across the different propensity score adjustment methods. The Inverse Probability of Treatment Weighting (IPTW) method was particularly effective in adjusting for covariate differences between groups, maintaining the full sample size, and providing a robust and clinically relevant analysis.

Conclusions: The anterior commissure is a significant risk factor for the recurrence of glottic cancer. Integrating propensity score methods enhances the precision and validity of survival studies. It is recommended to continue exploring these methods in larger and more diverse cohorts.