Primary Clear Cell Adenocarcinoma of the Head and Neck: A Population-Based Analysis

Objective: To characterize the epidemiology and clinicopathologic determinants of survival following the diagnosis of clear cell adenocarcinoma in the head and neck region. Study Design: Retrospective cohort study. Setting: The Surveillance, Epidemiology, and End Results registry (1994 to 2014). Subjects and Methods: A total of 173 cases were identified. Study variables included age, sex, race, tumor subsite, tumor stage, tumor grade, surgical excision, and regional and distant metastases. Survival measures included overall survival (OS) and disease-specific survival (DSS). Results: Median age at diagnosis was 63 years, 48% were female, and 80.2% were white. Fourteen percent of patients presented with regional lymph node metastases, while 3.3% of patients presented with distant metastases. Most of the tumors presented in the oral cavity, salivary glands, and pharynx. Kaplan-Meier analysis demonstrated OS and DSS of 77.2% and 83.7% at 5 years, respectively. Median OS after diagnosis was 153 months. Bivariate analysis showed that surgical excision was associated with 5-fold increased OS and DSS, whereas advanced age, high tumor grade, advanced stage, larger tumor size, nodal disease, and distant metastases were all significant predictors of decreased OS and DSS. Conclusions: Clear cell adenocarcinoma is a rare neoplasm that typically affects white individuals in their early 60s, with a generally favorable prognosis. It most commonly arises in the oral cavity, major salivary glands, and pharynx. Surgical excision is associated with 5-fold survival benefit, whereas advanced age, high tumor grade, advanced stage, nodal disease, and distant metastases are independently associated with worse OS and DSS.