Effective Radiotherapy in Tracheobronchial Adenoid Cystic Carcinoma with Positive Surgical Margin

Abstract Background The study aimed to evaluate the role of postoperative radiotherapy (PORT) in the treatment of trachea and main bronchus adenoid cystic carcinoma (ACC) with a positive surgical margin. Methods Patients with pathologically confirmed trachea or main bronchus ACC operated on at Shanghai Chest Hospital were enrolled. Survival, univariate, and multivariate analyses were performed. Chi-square test was applied to analyze the failure patterns among different groups (R0/0: negative margin resection without PORT; R1/0: positive margin resection without PORT; R1/1: positive margin resection with PORT). Results From January 2001 to December 2014, 77 patients were deemed eligible for the study. Pairwise comparisons showed that the overall survival rate of group R1/1 was comparable to that of group R0/0 (P=0.438), while significantly longer than the rate of group R1/0 (P=0.032). Besides, the local disease-free survival rate of group R1/1 was much higher than that of group R0/0 (P=0.023) and R1/0 (P=0.001). Cox multivariate analysis identified the radiological feature(P=0.012) and PORT (P=0.006) as significantly favorable prognostic factors for locoregional disease-free survival. By contrast, for overall survival, PORT (P=0.032) was the only corresponding variable identified by univariate analysis. Furthermore, PORT significantly decreased the locoregional recurrence rate (P=0.002) but not distant metastases (P=1.000). Conclusions PORT helped patients with tracheobronchial ACC and microscopic positive surgical margins to achieve a similar outcome as patients with complete resection. R0 resection may not be necessary for tracheobronchial ACC if it's hard to be completely resected.