Impact of positive margins and radiation after tracheal adenoid cystic carcinoma resection on survival.

Achieving negative margins for adenoid cystic carcinoma (ACC) of the trachea can be technically difficult. This study evaluated the impact of positive margins on prognosis and tested the hypothesis that radiation improves survival in the setting of incomplete resection.The impact of margin status and adjuvant therapy on overall survival of patients with tracheal ACC in the National Cancer Data Base (1998-2014) who underwent resection with known margin status and with no documented nodal or distant disease, was evaluated using Kaplan-Meier and Cox proportional hazard analysis.Of 132 patients who met study criteria, 79 (59.8%) had positive margins following resection. Adjuvant radiation was given to 95 (72.0%) patients overall and to 62 (78.5%) of the 79 patients with positive margins. The survival of patients with positive margins was not significantly different than the survival of patients with negative margins (5-year survival 82.2% [95% CI: 71.3-89.3] vs 82.0% [95% CI: 67.0-90.6], p=0.97), even after multivariable adjustment (HR, 1.73; 95% CI: 0.62-4.84; p=0.30). In the subset of patients with positive margins, there was no significant difference in survival between patients who did or did not receive postoperative radiation therapy (5-year survival: 82% [95% CI: 68.8-89.9] vs 82.4% [95% CI: 54.7-93.9], p=0.80), even after multivariable adjustment (HR, 1.04; 95% CI: 0.21-5.25; p=0.96).The majority of tracheal ACC resections performed in this national cohort had positive margins. Adjuvant radiation was commonly used for positive margins but was not associated with an overall survival benefit.