To Örebro University

Introduction: Head and neck cancer of unknown primary (HNCUP) is a rare condition whose prognostic factors that are significant for survival vary between studies. No randomized treatment study has been performed thus far, and the optimal treatment is not established.

Objective: The present study aimed to explore various prognostic factors and compare the two main treatments for HNCUP: neck dissection and (chemo) radiation vs primary (chemo) radiation.

Methods: A national multicenter study was performed with data from the Swedish Head and Neck Cancer Register (SweHNCR) and from the patients' medical records from 2008 to 2012.

Results: Two-hundred and sixty HNCUP patients were included. The tumors were HPVpositive in 80%. The overall 5-year survival rate of patients treated with curative intent was 71%. Age (p < 0.001), performance status (p = 0.036), and N stage (p = 0.046) were significant factors for overall survival according to the multivariable analysis. Treatment with neck dissection and (chemo) radiation (122 patients) gave an overall 5-year survival of 73%, and treatment with primary (chemo) radiation (87 patients) gave an overall 5-year survival of 71%, with no significant difference in overall or disease-free survival between the 2 groups.

Conclusions: Age, performance status, and N stage were significant prognostic factors. Treatment with neck dissection and ( chemo) radiation and primary (chemo).