Advancing Education, Research, and Quality of Care for the Head and Neck oncology patient.
Introduction: Adenoid cystic carcinoma (ACC) is an uncommon malignancy typically arising from major and minor salivary glands of the head and neck. However, ACC also occurs in sites outside of the head and neck; data regarding the behavior, management of prognosis of ACC is sparce. Here, we present a comparison of the clinical behavior, treatment patterns, and survival outcomes of ACC of the head and neck and other non-head and neck sites using the National Cancer Database (NCDB).
Methods: This was a retrospective analysis of patients diagnosed with adenoid cystic carcinoma between 2004 and 2020 in NCDB. Patients were identified using the histology code 8200 and categorized by site based on primary site ICD-O-3 codes. Anatomic sites with more than 100 patients were included for analysis. Survival was calculated using the Kaplan Meier method and hazard ratios (HR) were calculated using univariate and multivariate Cox proportional hazards regressions.
Results: A total of 17149 patients with ACC were identified in NCDB; seven sites (major salivary, minor salivary, respiratory, skin, breast, female genitourinary, and eye/orbit) were included for additional analysis by site with a total of 16962 patients included in the final analysis. Among all sites, minor salivary gland tumors were most likely to present with locally advanced disease (T3 or T4) while those of the respiratory tract were most likely to present with regional (26%) or distant metastasis (11.1%). Tumors of the eye/orbit often presented with locally advanced disease (54%) but rarely had regional or distant metastasis. On univariate analysis, skin (HR 0.64, 95% CI 0.54-0.75) and breast (HR 0.41, 95% CI 0.37-0.46) primaries had improved survival relative to major salivary gland primaries while minor salivary gland (HR 1.22, 95% CI 1.15-1.30), respiratory (HR 1.88, 95% CI 1.69-2.10), and eye/orbit (HR 1.27, 95% CI 1.08-1.50) primaries had worse survival. On multivariate analysis controlling for age, sex, treatment, T and N classification, only breast primaries had significantly different survival from major salivary primaries (HR 0.50, 95% CI 0.43-0.58)
Conclusion: The clinical behavior of ACC varies significantly by anatomic primary site. Survival differences between the different anatomic site appears to be driven largely by differences in the extent of disease at presentation, although patients with breast primaries have significantly better survival than major salivary gland primaries even when controlling for these factors.