Prognostic Value and Optimal Candidates of Primary Tumor Surgery in Metastatic Adenoid Cystic Carcinoma of the Head and Neck: First Evidence from a Population-Based Study

Abstract

Objective: The prognostic value of primary tumor surgery (PTS) for patients with metastatic adenoid cystic carcinoma of the head and neck (HNACC) at initial diagnosis has never been studied. The aims of this study were to determine the prognostic significance and identify optimal candidates of PTS.Materials and Methods: Patients with metastatic HNACC (stage IVC) at initial diagnosis were identified from the Surveillance, Epidemiology and End Results (SEER) database between 2004 and 2015. Correlated variables, including age, sex, race, tumor stage, metastatic site, treatment, and survival information were extracted. Kaplan-Meier analysis, log-rank test, and multivariate Cox regression model were performed to evaluate the impact of PTS on survival outcomes, including overall survival (OS) and cancer-specific survival (CSS).Results: Overall, 155 patients were identified from database. Of those, 93 (60%) patients underwent palliative PTS. Patients with lung metastasis alone were more likely undergo PTS (c2=15.042, P=0.002). The univariate analysis showed that PTS were associated with significantly improved survival than no-PTS (P=0.001 for CSS; P＜0.001 for OS). The median CSS for patients who received PTS and those who did not receive PTS were 64.0 and 22.0 months, respectively. The median OS for patients who received PTS and those without PTS were 43.0 and 16.0 months, respectively. Notably, in multivariate model, the OS of patients who underwent PTS was better than that of patients who did not (HR=0.586, P=0.017), but there was no significantly improvement in CSS. In addition, subgroup analyses further revealed that patients with T3-4 or N0 stage might benefit from PTS.Conclusion: PTS signifi­cantly improved OS in patients with metastatic HNACC. Besides, PTS had a favorable prognostic impact on highly-selected patients, namely T3-4 and N0 stage, which could be adopted in future clinical practice. Further multicenter prospective studies are still needed to verify these outcomes.