Predictors of Distant Metastasis and Survival in Adenoid Cystic Carcinoma of the External Auditory Canal.

Abstract

To analyze the predictors of both distant metastasis and survival in patients with adenoid cystic carcinoma of the external auditory canal. Retrospective patient review. A single university hospital. Eighty-two cases with adenoid cystic carcinoma of the external auditory canal were referred to our institution between 2004 and 2016. Distant metastasis was detected by lung computed tomography, proton emission tomography computed tomography, or histopathologic examination of tissue samples. Distant metastasis predictors were analyzed using Student's t tests and χ tests. The log-rank tests of Kaplan-Meier survival curves were used to evaluate survival differences. During a median follow-up of 36 months (range, 6-162 mo), distant metastasis developed in 25 patients. The occurrence of distant metastasis was significantly associated with histopathologic subtype, T classification, and local recurrence (p < 0.05). The 1-, 10-, 20-, and 25-year cumulative survival rates in the patents with DM were 95.7, 95.7, 71.7, and 0%, respectively, and all survival rates were 100% for the 57 patients without distant metastasis (p = 0.115). Median survival time after occurrence of distant metastasis was 13 months (range, 1-120 mo). Prognosis was better with solely lung metastasis than with metastases to other visceral organs or bone (p < 0.05). Distant metastasis appeared to result in a poorer prognosis, occurrence of distant metastasis was significantly associated with local recurrence, extensive surgery is recommended to achieve local control and reduce distant metastasis risk. Routine follow-up investigations for detecting distant metastasis are warranted for patients with an increased risk for distant metastasis.