Date of Award

January 2015

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Benjamin L. Judson

Subject Area(s)

Medicine

Abstract

Objective: The aim of this work was to determine the prognostic impact of positive margins in early oral cavity squamous cell cancer and evaluate the utility of positive margin incidence as a surgical quality measure.

Study design and setting: Retrospective analysis of the National Cancer Data Base

Subjects and methods: Patients with oral cavity squamous cell cancer diagnosed between 1998 and 2011 who were treated with surgical resection were sampled. Univariate and multivariate analyses of overall survival and incidence of positive margins were performed.

Results: A total of 6,830 patients were included in the survival analysis. Overall survival at 5-years was 69.7%. On multivariate analysis, neck dissection (HR 0.79, 95% CI 0.76-0.94) and treatment at academic/research institutions (HR 0.88, 95% CI 1.01-0.99) were associated with improved survival, while positive margins (HR 1.27, 95% CI 1.08-1.49), insurance through Medicare (HR 1.45, 95% CI 1.25-1.69) or Medicaid (HR 1.96, 95% CI 1.60-2.39), and adjuvant radiotherapy (HR 1.31, 95% CI 1.16-1.49), or adjuvant chemotherapy (HR 1.34, 95% CI 1.03-1.75) were associated with compromised survival. A total of 20,602 early oral cancer patients were identified for analysis of factors associated with positive margins. Margin status was reported in 94.8% of cases, and positive margins occurred in 7.5% of those cases. Incidence of positive margins by institution varied from 0% to 43.8%, with median incidence of 7.1%. Positive margins were associated with clinical factors including stage II disease (OR 1.75; 95% CI 1.55-1.98), intermediate grade (OR 1.20; 95% CI 1.04-1.37), high grade (OR 1.68; 95% CI 1.39-2.03), and floor of mouth (OR 1.78; 95% CI 1.52-2.08), buccal mucosa (OR 2.06 95% CI 1.59-2.68), and retromolar locations (OR 2.40, 95% CI 1.85-3.11). Positive margins were also associated with treatment at non-academic cancer centers (OR 1.23; 95% CI 1.04-1.44) and institutions with low oral cancer case volume (OR 1.45; 95% CI 1.23-1.69).

Conclusion: Positive margins portend a poor prognosis in early oral squamous cell cancer. The incidence of positive margins is associated with clinicopathologic factors as well as treatment and institution factors and can serve as an effective surgical quality measure for early oral cavity squamous cell cancer.

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