Purpose: To validate the recursive partitioning analysis (RPA) classification system for squamous cell head and neck cancer as recently reported by the VU University Medical Center.
Methods and materials: In eight Dutch head and neck cancer centers, data necessary to classify patients according to the RPA system were retrospectively collected from the charts of a group of 780 patients treated between 1989 and 2003. The patients in this validation group were classified according to the RPA classification system. For each endpoint, the 5-year values and hazard ratios were calculated and compared with the results of the VU University Medical Center. The RPA classification system was considered valid if the hazard ratio of the validation population was within the 95% confidence interval of the VU University Medical Center study population.
Results: The locoregional control rate was 82%, 75%, and 63% at 5 years for those with class I, II, and III, respectively (p < 0.0001). The hazard ratio for the locoregional control rate relative to class I was 1.44 (95% confidence interval, 0.97-2.16) for class II and 2.37 (95% confidence interval, 1.57-3.57) for class III. Similar results were found for the distant metastasis, overall survival, and disease-free survival rates.
Conclusion: The RPA classification system for head and neck squamous cell carcinoma in the postoperative setting, which was originally designed at one center, proved to be valid in a multicenter setting among patients included in a national multicenter study. This validated RPA classification scheme can be used to assess standard treatment strategies for head and neck squamous cell carcinoma in the postoperative setting, as well as in the design of future prospective studies.