Bilateral vs ipsilateral adjuvant radiotherapy in patients with cancer of unknown primary of the head and neck: An analysis of the clinical outcome and radiation-induced side effects.

Background: The purpose of this study was to analyze and compare ipsilateral and bilateral adjuvant radiotherapy in patients with cancer of unknown primary (CUP) of the head and neck.

Methods: Overall survival, recurrence-free survival, and radiation-induced side effects were assessed in 76 patients with CUP who underwent ipsilateral (n = 29) or bilateral (n = 47) radiotherapy.

Results: At a median follow-up of 41 months, the 5-year overall survival and recurrence-free rate were 67.9% and 71.5%, respectively. No statistically significant difference between ipsilateral and bilateral radiotherapy could be found regarding 5-year overall survival, recurrence-free survival, occurrence of a primary tumor, and distant metastasis. The analysis of radiation-induced acute side effects showed a significant benefit of ipsilateral radiotherapy.

Conclusion: As the main parameters of the study regarding the outcome and radiation-induced side effects showed no advantages of bilateral radiotherapy, the strategy of ipsilateral radiotherapy can be recommended for the adjuvant treatment of CUP patients.