Improvement in survival of patients with oral cavity squamous cell carcinoma: An international collaborative study

BACKGROUND An association between the survival of patients with oral cavity squamous cell carcinoma (OCSCC) and advancements in diagnosis and therapy has not been established. METHODS This was a retrospective, longitudinal, international, population-based study of 2738 patients who underwent resection of OCSCC during 2 different decades. Characteristics of patients from 7 international cancer centers who received treatment between 1990 and 2000 (group A; n = 735) were compared with patients who received treatment between 2001 and 2011 (group B; n = 2003). RESULTS Patients in group B had more advanced tumors and tended to develop distant metastases more frequently than patients in group A (P =.005). More group B patients underwent selective neck dissection and received adjuvant radiotherapy (P <.001). Outcome analysis revealed a significant improvement in 5-year overall survival, from 59% for group A to 70% for group B (P <.001). There was also a significant improvement in disease-specific survival associated with operations performed before and after 2000 (from 69% to 81%, respectively; P <.001). Surgery after 2000, negative margins, adjuvant treatment, and early stage disease were independent predictors of a better outcome in multivariate analysis. The decade of treatment was an independent prognostic factor for cancer-specific mortality (hazard ratio, 0.42; 95% confidence interval, 0.3-0.6). CONCLUSIONS The survival rate of patients with OCSCC improved significantly during the past 2 decades despite older age, more advanced disease stage, and a higher rate of distant metastases. The current results suggest that the prognosis for patients with OCSCC has improved over time, presumably because of advances in imaging and therapy.