Comparison of outcomes of locoregionally advanced oropharyngeal and non-oropharyngeal squamous cell carcinoma over two decades

Human papillomavirus (HPV) has emerged as a causative agent and positive prognostic factor for oropharyngeal (OP) head and neck squamous cell cancer (HNSCC). This prompts inquiry into whether therapy improvements or increasing incidence of HPV drives the apparent improvements in HNSCC outcomes observed in non-randomized clinical trials. We reviewed all locoregionally advanced HNSCC patients treated with chemotherapy and radiation in prospective institutional trials at a single institution. Patients were divided into three groups (1, 2, 3) according to treatment time period (1993-1998, 1999-2003, 2004-2010, respectively). We reasoned that if a favorable trend was observed over time in OP but not non-OP patients, HPV status may be confounding treatment effects, whereas this would be unlikely if both subgroups improved over time. Four hundred and twenty-two patients were identified with OP (55.7%) and non-OP (44.3%) HNSCC. Five-year OP overall survival (OS) improved from 42.3% (group 1) to 72.5% (group 2), and 78.4% (group 3), adjusted P = 0.0084. Non-OP 5-year OS was 51.0% (group 1), 58.8% (group 2), and 66.3% (group 3), adjusted P = 0.51. Five-year recurrence-free survival (RFS) improved for OP groups from 42.3% to 68.4% to 75.8% (adjusted P = 0.017). Non-OP 5-year RFS was 42.9%, 53.6%, and 61.7% for sequential groups (adjusted P = 0.30). Five-year OP distant failure-free survival (DFFS) improved from 42.3% to 71.1% to 77.8% (adjusted P = 0.011). Five-year non-OP DFFS was 46.9%, 57.1%, and 66.0% for sequential groups (adjusted P = 0.38). Over the past two decades, OP HNSCC outcomes improved significantly, while non-OP outcomes only trended toward improvement. Although our patients are not stratified by HPV status, improving OP outcomes are likely at least partly due to the increasing HPV incidence. These data further justify trial stratification by HPV status, investigations of novel approaches for carcinogen-related HNSCC, and current de-intensification for HPV-related HNSCC.