A comparison between p16-positive head and neck cancer of unknown primary (HPV-HNCUP) and oropharyngeal squamous cell carcinoma (HPV-OPSCC): are they the same disease?

INTRODUCTION: The following study aimed to answer the question if HPV-HNCUP and HPV-OPSCC are the same disease. Propensity score matching (PSM) was used to compare the oncological outcomes of both groups, in particular the 5-year overall survival rate (OS), the 5-year disease specific survival rate (DSS) and the 5-year progression free survival rate (PFS).

MATERIALS AND METHODS: Firstly, between January 1st, 2007, and March 31st, 2020 a total of 131 patients were treated with HNCUP at our Department. Out of these, 21 patients with a confirmed positive p16 status were referred to surgery followed by adjuvant therapy. Secondly, between January 1st, 2000, and January 31st, 2017, a total of 1596 patients were treated with an OPSSC at our Department. Out of these, 126 patients with a confirmed positive p16 status were referred to surgery followed by adjuvant therapy. After PSM, 84 patients with HPV-OPSCC and 21 HPV-HNCUP remained in the study for further comparison.

RESULTS: The OS was 63.5% (95% CI 39.4-87.6) for HPV-HNCUP and 88.9% (95% CI 90.4-100.0) for HPV-OPSCC patients and therefore, significantly lower for the first mentioned (p = 0.013). The DSS was also significantly impaired for HPV-HNCUP (71.0%, 95% CI 46.3-95.7), in comparison with HPV-OPSCC patients (95.5%, 95% CI 90.4-100.0; p = 0.002). The PFS for HPV-HNCUP patients was lower (75.6%, 95% CI 54.0-97.2) yet not significantly different to HPV-OPSCC (90.4%, 95% CI 83.5-97.3; p = 0.067).

CONCLUSIONS: The results presented demonstrate a significant reduced OS and DSS for HPV-HNCUP patients. Accordingly, in our study HPV-HNCUP and HPV-OPSCC are two different entities with a different oncological outcome.