POSTOPERATIVE RADIATION-THERAPY FOR SQUAMOUS-CELL CARCINOMAS OF THE ORAL CAVITY AND OROPHARYNX - IMPACT OF THERAPY ON PATIENTS WITH POSITIVE SURGICAL MARGINS

Purpose: The presence of a positive or close margin after resection of a squamous cancer of the head and neck is associated with a significant risk of local recurrence. To determine the efficacy of postoperative radiation therapy for patients with advanced oral cavity and oropharyngeal cancers with inadequate margins of resection, the present retrospective analysis was undertaken. Methods and Materials: One hundred and two patients were treated with surgery and postoperative radiation therapy for advanced squamous cell carcinomas of the oral cavity and oropharynx. The anatomic subsites treated include oral tongue (n = 29), floor of mouth (n = 22), base of tongue (n = 31) and tonsillar fossa (n = 20). Twenty-five patients (25%) had positive margins, 41 patients (40%) had close margins (less-than-or-equal-to 0.5 cm from the surgical margin) and 36 (35%) had negative margins. The median radiation dose was 6000 cGy. Results: With a median follow-up of 7 years, the actuarial control rate for patients with positive, close and negative margins was 79%, 71%, and 79%, respectively. When postoperative doses of greater-than-or-equal-to 60 Gy were delivered to patients with positive/close margins (excluding patients with oral tongue lesions), the 7-year actuarial control was 92%. In similar patients receiving < 60 Gy, the actuarial control was 44% (p = 0.0007). Compared to other anatomic subsites, inferior control rates were obtained with oral tongue lesions, For this subsite, the control rates for positive, close, and negative margins were 50%, 62% and 69% respectively. Conclusion: We conclude that excellent local control can be achieved with postoperative radiation therapy, despite the presence of inadequate margins of resection, when doses of greater-than-or-equal-to 60 Gy are used. Future strategies must be directed at further improving these results in patients with oral tongue lesions.