Survival outcomes of patients with advanced oral cavity squamous cell carcinoma treated with multimodal therapy: a multi-institutional analysis

Background: The oral cavity is the most common site for head and neck squamous cell carcinoma. Treatment of advanced stage oral cavity squamous cell carcinoma (OCSCC) has classically involved surgical resection with postoperative adjuvant radiotherapy (S-RT). Despite this aggressive dual modality therapy, the disease outcomes have remained poor. The treatment options expanded in 2004 when two international trials showed the addition of postoperative chemotherapy to radiation improved outcomes. These trials were, however not oral cavity site specific. Objective: To assess survival outcomes of advanced OCSCC treated by differing modalities. The primary goal was to determine if the addition of postoperative chemotherapy (S-CRT) improves survival compared to other treatment regimens. Methods: Demographic, pathologic, treatment, and survival data was obtained from patients diagnosed with OCSCC from 1998-2010 in Alberta, Canada. 222 patients were included in the final analysis from 895 OCSCC patients. Actuarial overall, disease-specific, disease-free, and metastasis-free survivals were estimated with Kaplan-Meier and Cox regression analyses. Patients were grouped by treatment. Results: Patients receiving S-CRT had improved overall, disease-specific, disease-free, and metastasis-free survival compared to S-RT, CRT or RT(p < 0.05). Two and five year estimated overall survival was significantly higher in the S-CRT group at 77 and 58% (p < 0.05), versus S-RT with 55 and 40% rates(p < 0.05). Results were similar for disease-specific, disease-free, and metastasis free survival with S-CRT being favoured. Patients with extracapsular spread (ECS) treated with S-CRT versus S-RT had 55% survival advantage at 5 years (p < 0.05). Conclusion: This study shows that adding adjuvant chemotherapy to S-RT improves survival outcomes in advanced OCSCC, especially in patients with ECS.