Prognostic factors in oropharyngeal cancer--analysis of 627 cases receiving definitive radiotherapy.

INTRODUCTION: The aim of this retrospective analysis was to analyze the results of conventional radical radiotherapy in the treatment of oropharyngeal cancer and to identify pre-treatment and treatment-related prognostic factors for outcome.

MATERIAL AND METHODS: The records of 627 patients with oropharyngeal cancer treated with radical radiotherapy with conventional techniques were analyzed.

RESULTS: The median age was 56 years. History of tobacco abuse was present in 80.5%. Eighty six percent had stage III or IV disease. Radical radiotherapy alone was the treatment modality for 71.2% and concomitant or neoadjuvant chemotherapy was used in 28.8%. The 3-year local control (LC), loco-regional control (LRC), disease-free survival (DFS) and overall survival (OS) was 49%, 40.6%, 38.9% and 36.1% respectively. The 3-year DFS rates were 80.3% for stage I, 65.8% for stage II, 46.1% for stage III and 25.2% for stage IV disease. Multivariate analysis was performed for prognostic factors. Prior history of tobacco abuse was an independent prognostic factor for both DFS and LRC. Karnofsky Performance Score (KPS) < 80, higher nodal stage, lower total radiotherapy dose (<66 Gy) in those receiving > 60 Gy, and overall treatment time > 50 days were other independent prognostic factors for inferior DFS and LRC. KPS < 80, higher T stage, higher nodal stage, RT dose < 66 Gy and longer overall treatment time (>50 days) were independent prognostic factors for poorer local control.

CONCLUSIONS: Several patient-, disease- and treatment-related variables independently affect survival outcomes after radical radiotherapy for oropharyngeal cancer. Oropharyngeal cancers in those without a history of tobacco abuse may be biologically different and more amenable to cure with radiotherapy.