Postoperative radiotherapy for patients at high risk of recurrence of oral cavity squamous cell carcinoma.

OBJECTIVES To evaluate the efficacy of postoperative radiotherapy for oral cavity squamous cell carcinoma (OCSCC) by comparing outcomes of high-risk subgroups. STUDY DESIGN Retrospective review. METHODS Outcome study of 139 patients with OCSCC treated with gross total resection and postoperative radiotherapy ± chemotherapy and at least one high-risk pathologic finding: positive margin (52%), close (0.1-5 mm) margin (27%), or extracapsular nodal extension (ECE; 45%). RESULTS Median follow-up was 2.3 years. Local-regional control (LRC), freedom from distant metastases, cause-specific survival, and overall survival (OS) rates at 5 years were 64%, 85%, 51%, and 36%, respectively. Five-year LRC for negative (>5 mm), close (0.1-5 mm), and positive (carcinoma in situ or tumor at ink) margins were 73%, 83%, and 63%, respectively (P = not significant). Five-year neck control was 100% for node-negative patients, 88% for node-positive patients with no ECE, and 86% for node-positive patients with ECE (P = not significant). The combination of close/positive margin and ECE resulted in worse 5-year LRC (37% vs. 70%, P < 0.001), progression-free survival (26% vs. 60%, P < 0.001), and OS (13 vs. 43%, P < 0.001) compared with a single high-risk indication. CONCLUSIONS Local-regional control was the predominant mode of treatment failure. Outcome in our series was not statistically different based on margin status or nodal ECE. This finding is indirect evidence of the efficacy of adjuvant radiotherapy in this setting.