Predictive Factors Affecting the Recurrence Time of Early Glottic Cancer : Long-term Follow-up Results

Abstract

Background: Recurrences of head and neck cancers generally appear within 5 years after initial treatment. However, recurrences of some early glottic cancers are observed more than 5 years after initial treatment. Clinicians have reported the incidence of late recurrence (over 5 years) in patients with glottic cancer who underwent radiation therapy. However, little is known about late recurrences in patients with early glottic cancer who have undergone surgical treatment. This study aimed to analyze recurrences of early glottic cancer and prognostic factors that had significant impacts on local tumor control and the relapse time. Methods: Using propensity score analysis, 330 patients with early glottic cancer were retrospectively analyzed. The propensity scores were estimated using a logistic regression model and applied to a covariate adjustment method among the 4 propensity score methods. Results: Overall, 127 patients treated with laser surgery and 203 patients treated with radiotherapy had 5 and 10-year local recurrence-free rates of 82.0% and 74.0%, respectively. T2 stage was significantly prognostic for local recurrence. Among patients with recurrent disease, laser treatment (P = 0.047) and anterior commissure non-involvement (P = 0.007) significantly affected the time to relapse even after propensity score analysis. The 49 patients (76.5%) with evidence of cancer recurrence within 5 years were designated as the early recurrence group. The 15 patients (23.5%) with evidence of cancer recurrence beyond 5 years were designated as the late recurrence group. Among patients (n = 182) who followed up more than 5 years, late recurrence (n = 15) was 8.2%. Among 15 late recurrent patients, 11 (73.3%) were concordant and 4 (26.7%) were discordant. Conclusions: There was no difference in overall and late recurrence between laser and RT. However, there was a difference in the timing of recurrence. Given the considerable rate of late recurrence and prognostic factor, follow-up of early glottic cancer cases should be extended beyond 5 years after initial treatment, especially for laser surgery.