Intensity modulated radiation therapy may improve survival for tracheal-bronchial adenoid cystic carcinoma: A retrospective study of 133 cases

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 < 0.001, R2 = 0.480) than LRFS (P < 0.001, R2 = 0.323). 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.