The clinical significance of the positive surgical margin in oral cancer.

The objective of surgical management of squamous cell carcinoma of the oral cavity is adequate resection with a clear margin. This study examines the significance of the positive surgical margin. An historical cohort of 425 patients from the cancer registry of the Province of Manitoba with squamous cell carcinoma of the oral cavity treated with surgery +/-radiotherapy was examined. A Cox's proportional hazard model was used to examine the independent effect of surgical margins on five-year survival. Seventy-two percent of tumors involved the tongue and floor of mouth, and 43% of patients presented with Stage III and IV disease. The 5-year absolute and disease specific survivals were 62% and 74.5% respectively. Survival was related to age >65 years (P=0.0177), T-Stage (P=0.0002), and N-Stage (P=0.0465). Patients with clear margins had a survival rate of 69% at 5 yrs (median survival >60 mos) compared to 58% with close (median survival >60 mos) and 38% with involved margins (median survival 31 mos, P=.0000). After controlling for significant prognostic factors, involved surgical margins increased the risk of death at 5 years by 90% (HR 1.9, 95% CI 1.2,2.9, P=0.0026). The status of the surgical margin is an important predictor of outcome. The surgical margin, in contrast to the other prognostic indicators, is under the direct control of the surgeon.