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.