Effect of human papillomavirus on patterns of distant metastatic failure in oropharyngeal squamous cell carcinoma treated with chemoradiotherapy.

IMPORTANCE Important differences exist in the pattern and timing of distant metastases between human papillomavirus-initiated (HPV+) and HPV- oropharyngeal squamous cell carcinoma (OPSCC). However, our understanding of the natural history of distant metastases in HPV+ OPSCC and its implications for surveillance is limited. OBJECTIVE To investigate the rate, pattern, and timing of distant metastases in advanced-stage OPSCC treated definitively with concomitant chemoradiotherapy. DESIGN, SETTING, AND PARTICIPANTS In a retrospective review, we identified 291 patients with pathologically diagnosed stages III to IVB OPSCC and known HPV status from a tumor registry at the Cleveland Clinic. Patients were treated from January 1, 1996, through December 31, 2013. Details of treatment failure and the natural history of the disease were retrieved from the electronic medical records. INTERVENTIONS All patients were treated with definitive concomitant chemoradiotherapy. MAIN OUTCOMES AND MEASURES The primary outcome was the rate and timing of distant metastases. Secondary outcomes included the pattern of distant failure and survival after distant metastases. RESULTS Thirty-seven patients developed distant metastatic disease after definitive treatment, including 28 of 252 patients with HPV+ disease and 9 of 39 patients with HPV- disease. The 3-year projected distant control rate was higher in the HPV+ group (88% vs 74%; P = .01). The median time to develop distant metastases was also longer after the completion of treatment for HPV+ disease compared with HPV- disease (16.4 vs 7.2 months; P = .008). We detected a trend in patients with HPV+ disease for more distant metastatic sites involved than in those with HPV- disease (2.04 vs 1.33 sites; P = .09). Although the lung was the most common distant site involved in HPV+ and HPV- disease (HPV+ group, 23 of 28 patients [82%]; HPV- group, 7 of 9 patients [78%]), the HPV+ group had metastases to several subsets atypical for head and neck squamous cell carcinoma, including the brain, kidney, skin, skeletal muscle, and axillary lymph nodes in 2 patients each and in the intra-abdominal lymph nodes in 3 patients. The rate of 3-year overall survival was higher in the HPV+ group (89.9% vs 62.0%; P < .001), as was the median survival after the occurrence of distant metastases regardless of additional treatment (25.6 vs 11.1 months; P < .001). CONCLUSIONS AND RELEVANCE This retrospective review suggests that distant metastases in patients with HPV+ OPSCC occurs significantly later after completion of chemoradiotherapy than in patients with HPV- disease. Human papillomavirus-initiated OPSCC also appears to involve a greater number of subsites and metastatic sites infrequently seen in head and neck squamous cell carcinoma. Distant metastatic disease in HPV+ OPSCC has unique characteristics and a natural history that may require alternative surveillance strategies.