Evaluation of postoperative radiotherapy in the treatment of supraglottic laryngeal squamous cell carcinoma

Abstract:

Objective To evaluate the role of postoperative radiotherapy（PORT） in supraglottic laryngeal squamous cell carcinoma.Methods The clinical data of 831 patients with supraglottic laryngeal squamous cell carcinoma selected from the SEER（Surveillance，Epidemiology，and End Results）database who received surgical treatment in 2004 to 2015 were retrospectively analyzed. Propensity score matching（PSM） was used to balance the covariate bias between the PORT（-） and PORT（+） groups. The survival curves were drawn by Kaplan-Meier method，and log-rank test was used to check survival difference of two groups and make subgroup analysis. And the overall survival（OS） and cancer specific survival（CSS） were compared between these two groups to analyze the value of PORT in the treatment of patients with supraglottic laryngeal squamous cell carcinoma.Results There was no significant difference in OS between the PORT（-） and PORT（+） groups before the PSM，while the CSS of the PORT（+） group was lower than that of the PORT（-） group（P=0.022）. The subgroup analysis of the number of positive lymph nodes showed that there was no significant difference in OS and CSS of patients with 0 or 1 positive lymph node. However，the patients with positive lymph nodes greater than 1 in PORT（+）group had significantly higher 5-year OS and CSS rate than those in the PORT（-）group（OS：23.1% vs. 38.1%，P<0.001；CSS： 34.8% vs. 45.3%，P=0.004）. After PSM，the OS and CSS rate in the PORT（+） group were both better than those of the PORT（-） group（OS： 55.1% vs. 41.9%，P=0.004；CSS：67.1% vs. 56.1%，P=0.042）. When analyzed by subgroup，patients with histological Ⅰ and Ⅱ stage，AJCC T4 stage，AJCC N2b stage or above，count of positive lymph nodes >1 and total laryngectomy had survival benefit for the PORT（+） group，with significant differences. And patients with lymph node ratio <20% and tumor size <30 mm without chemotherapy only had OS benefit associated with PORT.Conclusion The use of PORT can improve the OS and CSS rate in supraglottic laryngeal squamous cell carcinoma，and the related beneficiary groups are patients with AJCC T4 stage，AJCC N2b stage or above，and the count of positive lymph nodes >1，which needs to be further evaluated for the role of PORT in patients with adverse pathological features in other similar studies.