Effects of adjuvant radiation therapy on survival for patients with resected primary tracheal carcinoma: an analysis of the National Cancer Database

Objective(s): To identify predictors for receiving adjuvant radiation therapy (RT) and investigate the impact of adjuvant RT on survival for patients with resected primary tracheal carcinoma (PTC). Methods: The National Cancer database was queried for patients with PTC diagnosed from 2004 to 2014 undergoing resection. Patients who died within 30 days of resection were excluded to minimize immortal time bias. Kaplan-Meier methods, Cox regression modeling and propensity score weighted (PSW) log-rank tests were considered to assess the relationship between adjuvant RT and overall survival (OS). Logistic regression was performed to identify predictors associated with receiving adjuvant RT. Results: A total of 549 patients were identified with 300 patients (55%) receiving adjuvant RT. Squamous cell carcinoma (SCC) was the most common histology with 234 patients (43%). Adenoid cystic carcinoma (ACC) was second most frequent with 180 patients (33%). Adjuvant RT was not associated with OS by multivariable Cox analysis or PSW log-rank test (P values > 0.05). Patients with positive surgical margins (odds ratio (OR) 1.80, confidence interval (CI) 1.06-3.07) were more likely to receive adjuvant RT than those with negative surgical margins. Patients with ACC (OR 6.53, CI 3.57-11.95) were more likely to receive adjuvant RT compared with SCC. Conclusions: Adjuvant RT was not significantly associated with OS for patients with resected PTC in this analysis. Surgical margin status and tumor histology were associated with receiving adjuvant RT. Further investigations including prospective registry studies capturing radiation technique and treatment volumes are needed to better define which patients with resected PTC may benefit from adjuvant RT.