Prognostic factors for squamous cell cancer of the parotid gland: an analysis of 2104 patients.

BACKGROUND Parotid gland squamous cell cancer (SCC) occurs as metastasis from cutaneous SCC or primary malignancy. There is limited data on incidence, prognosis, and treatment outcomes. METHODS The Surveillance, Epidemiology, and End Results (SEER) database (1988-2009) identified 2104 adult patients with parotid SCC. RESULTS SCC is the second most common parotid malignancy, and its incidence is increasing (annual percentage change 1.7%; ptrend  = .004). Age ≥85 years, tumor size ≥4 cm, extraparenchymal extension, cervical metastases, and distant metastases were independently associated with disease-specific mortality. Compared to no surgery, surgery was associated with improved 5-year disease-specific survival (DSS; 44.4% vs 71.0%; p < .001), whereas radiation alone was similar to no treatment (47.0% vs 41.6%; p = .28). CONCLUSION Surgery and adjuvant radiation therapy (RT) are associated with improved survival compared to radiation alone and no treatment. Patients ≥85 years of age account for nearly 20% of all patients and have a poor prognosis independent of treatment.