The Impact of Margin Status Following Surgery for Metastatic Cutaneous Squamous Cell Carcinoma to the Parotid Gland.

Abstract

Metastatic cutaneous squamous cell carcinoma (cSCC) to the parotid is increasing in incidence, and surgery remains the primary treatment modality. A previous publication investigating the outcomes of microscopically involved margins (R1) on the facial nerve found that survival is not compromised when a nerve-sparing approach with adjuvant radiotherapy is employed. However, it is unknown whether this approach is reasonable in all situations where achieving a clear surgical margin requires the sacrifice of important anatomic structures. The aim of this study is to analyze an expanded cohort of patients with metastatic cSCC to the parotid to test the hypothesis that an involved surgical margin during parotidectomy is associated with worse outcomes. Patients who were treated surgically with curative intent for metastatic cSCC to the parotid with a known margin status were identified from a prospectively maintained database. Demographic, staging, and treatment details were recorded as well as recurrence and survival data. The cohort was analyzed for associations with regional control in the parotid and neck (RC), distant control, and disease-specific survival (DSS). Overall survival (OS) was not analyzed due to competing risks. This study analyzed 291 patients, with a mean age of 74 years. Most patients received adjuvant radiotherapy (63%). The estimated 5-year OS was 45%, DSS was 77%, with a RC rate of 92%. An involved parotid nodal margin was associated with worse RC (p = 0.04), distant control (p = 0.04) and DSS (p = 0.01). After adjusting for confounders, an involved margin was associated with 114% higher risk of disease-specific death (HR 2.14, 95% CI 1.12-4.11, p = 0.022) but there was no statistical difference in RC (p = 0.068). An involved microscopic parotid nodal margin is associated with significantly worse DSS.