An Improved Staging System of Adenoid Cystic Carcinoma in the External Auditory Canal.

ABSTRACT

OBJECTIVE: The purpose of this study was to define an improved staging system for adenoid cystic carcinoma (ACC) in the external auditory canal (EAC) based on biological behaviors, image findings, and the prognosis of patients with ACC in the EAC. STUDY DESIGN: A retrospective study. SETTING: A single center data. METHODS: We performed a single-institution retrospective review of 154 patients with ACC in the EAC between January 2004 and September 2021. Risk factors associated with disease-free survival (DFS) and cancer-specific survival (CSS) of ACC in the EAC were identified using univariate and multivariate cox regression analysis. Then an improved staging system was proposed and compared with the Pittsburgh-modified tumor, node, and metastasis (TNM) staging system for statistical differences in DFS and CSS. RESULTS: An improved staging system of ACC in the EAC was defined, in which stage T4 were subclassified into T4a and T4b and were statistically different from the Pittsburgh-modified TNM staging system in DFS and CSS. We also found that the dura mater, facial nerve, sigmoid sinus, deep lobe of parotid gland, and parapharyngeal space involvement were significantly associated with poor prognosis of ACC in the EAC. CONCLUSION: The improved staging system is more accurate in predicting survival prognosis than Pittsburgh-modified TNM staging system for patients with ACC in the EAC, and may provide more efficient guidance of treatment strategy. SUMMARY: The improved staging system of ACC in the EAC is more accurately to predict survival prognosis, and provide guidance of treatment plan than Pittsburgh-modified TNM staging system.