Head and neck sweat gland adenocarcinoma: A population-based perspective of a rare entity.

OBJECTIVES

Head and neck sweat gland adenocarcinoma (HNSGA) is an extremely rare malignancy. We present the first population-based analysis regarding this entity.

STUDY

DESIGN

Retrospective population-based analysis.

METHODS

Using the Surveillance, Epidemiology, and End Results registry from 2000 to 2013, we extracted 627 cases of HNSGA. Data were analyzed for incidence trends, demographic and clinicopathologic traits, and predictors of disease-specific survival (DSS).

RESULTS

The majority HNSGA cases were white, male, and 60 to 79 years old. The incidence was 0.036 per 100,000 people. Tumors most often presented as localized disease and histological grade II/III. The skin of the face was the most common primary site (43.4%), followed by the scalp and neck (31.6%). Overall 5-, 10-, and 20-year DSS were 94.6%, 89.6%, and 79.8%, respectively. Ethnicity did not affect survival, whereas a younger age at diagnosis and female sex conferred an advantage at 10 years (P = 0.0386) and 5 years (P = 0.0191), respectively. The origin of the HNSGA (apocrine vs. eccrine) did not affect outcomes. Regional and distant disease predicted worse DSS at 5, 10, and 20 years (P = 0.0026, P < 0.001, P < 0.001, respectively). Compared to grade I/II disease, grade III/IV dramatically worsened 5-, 10-, and 20-year DSS (P = 0.0035, P < 0.0001, P = 0.0011, respectively). Scalp and neck HNSGA exhibited the poorest 20-year DSS compared to other primary sites (P = 0.0024).

CONCLUSION

We present the largest cohort of HNSGA. Significant poor prognostic indicators include older age, higher tumor grade, greater extent of invasion, and primary site of the scalp or neck.

LEVEL OF EVIDENCE: 4. Laryngoscope, 127:2757-2762, 2017.