Polymorphous low‐grade adenocarcinoma of the head and neck: A population‐based study of 460 cases

OBJECTIVES/HYPOTHESIS: Polymorphous low-grade adenocarcinoma (PLGA) is a rare malignant neoplasm of the minor salivary glands. This study analyzes the demographic, clinicopathologic, incidence, and survival characteristics of head and neck PLGA (HN-PLGA). METHODS: The Surveillance, Epidemiology, and End Results (SEER) database was queried for HN-PLGA cases from 2001 to 2011 (460 cases). Data analyzed included patient demographics, incidence trends, and survival outcomes. RESULTS: Head and neck PLGA occurred most frequently in the sixth and seventh decades of life. Mean age at diagnosis was 61.3 (± 15.0) years. There was a female predilection with a female-to-male ratio of 2.15:1. There was a predilection toward blacks among the US population, with black-to-white incidence rate ratio of 2.33:1. The most common site of HN-PLGA was the palate (57.2%), followed by the lip (7.0%). Average tumor size was 2.1 (± 1.3) cm at presentation. The majority of cases were localized at the time of presentation (70.5%), with rare distant metastasis (4.3%). The most common treatment modality was surgery alone (77.9%), followed by surgery with radiotherapy (19.5%). Elective neck dissection was performed in 5.3% of the cases. Survival analysis showed excellent 10-year disease-specific (96.4%) and relative (94.7%) survival rates. Ten-year disease-specific survival was better among those treated with surgery alone (98.0%) or surgery with adjuvant radiotherapy (90.9%) than those treated with radiotherapy alone (75.0%) (P < 0.0001). CONCLUSION: This study represents the largest cohort of HN-PLGA cases. Head and neck PLGA shows a predilection for women and blacks in the US population. It has an excellent survival outcome with surgery being the treatment of choice.