Intensity Modulated Radiation Therapy May Improve Survival for Tracheal-Bronchial Adenoid Cystic Carcinoma: A Retrospective Study of 133 Cases

Abstract Purposes This study aimed to evaluate the role of radiotherapy (RT) and intensity modulated radiation therapy (IMRT) in adjuvant and definitive settings of tracheal-bronchial adenoid cystic carcinoma (TACC) treatment. Materials/Methods TACC patients (n = 133) treated with surgery and/or RT curatively in our institution between January 1st, 1984 and December 31st, 2017 were analyzed retrospectively. Results Among the 116 patients undergoing surgery, 50 (43.1%) achieved complete resections and 66 (56.9%) had positive surgical margins. For patients with positive margins, overall adjuvant RT was correlated with no significantly improved OS (10-year: 58.0% vs. 47.9% P =  0.340) and a slight LRFS benefit (5-year: 81.9% vs.75.6%; P =  0.056), but adjuvant IMRT showed significant superiority in both OS (10-year: 82.9% vs. 47.9%; P =  0.031) and LRFS ( 5-year: 100.0% vs. 75.6%; P =  0.001) in comparison with no postoperative RT. Multivariate analysis also identified adjuvant IMRT as a significant favorable factor with OS (HR = 0.186, 95%CI: 0.039-0.883; P =  0.034). For 17 patients receiving definitive RT, IMRT achieved promising 5-year OS of 88.9% and LRFS of 64.3%, yet no significant difference from non-IMRT group was reached (P = 0.447 and 0.706). Different therapies presented no significantly different impact on DMFS, whilst DMFS explained more of the OS variances (P  Conclusion IMRT could confer greatly improved OS and LRFS in postoperative setting for TACC patients with positive surgical margins. IMRT was also a good therapeutic option for definitive TACC with promising survival and local control.