Prognostic Impact of Synchronous and Metachronous Second Primary Cancers in Laryngeal Cancer Patients Treated With Radiotherapy: Variable With Time-Varying Effects and Cox Proportional Hazard Analyses.

Abstract

Aims: Patients with laryngeal and other head and neck cancers face a high risk of developing second primary cancers. This retrospective cohort study evaluated the prognostic value of second primary cancers in laryngeal cancer patients treated with radiotherapy.

Methods: We retrospectively investigated patients with laryngeal cancer who underwent radiotherapy, and evaluated the incidence and relative risk of synchronous and metachronous second primary cancers in a single-institution cohort.

Results: Between January 2007 and December 2021, 138 patients with laryngeal cancer were analyzed. The median follow-up period was 5.2 years. The 5-year overall survival rate was 82.4% and the progression-free survival rate was 71.9%. Synchronous and metachronous second primary cancers were observed in 15 (10.9%) and 38 (27.5%) patients, respectively, during the follow-up period. The cumulative incidence of metachronous second primary cancers was 23.3% at 5 years. Moreover, deaths from laryngeal cancer, other cancers, and noncancer illnesses accounted for 3.6% (5 patients), 12.3% (17 patients), and 10.9% (17 patients), respectively, with most deaths from causes other than laryngeal cancer occurring after the first 5 years. Synchronous second primary cancer was a significant prognostic factor of poor outcomes (hazard ratio, 4.42; 95% confidence interval, 1.93-10.13) on time-independent multivariate analysis, and metachronous second primary cancer was a significant prognostic factor of poor outcomes (hazard ratio, 4.55; 95% confidence interval, 2.09-9.91) in the time-dependent Cox proportional hazards model.

Conclusion: Synchronous and metachronous second primary cancers are significant prognostic factors for patients with laryngeal cancer treated with radiotherapy.