Patterns of failure in patients with head and neck carcinoma of unknown primary treated with radiation therapy

Background The purpose of this study was to examine patterns of failure and the relationship to radiation doses in patients with head and neck carcinoma of unknown primary (HNCUP). Methods We reviewed 85 patients with HNCUP treated with curative-intent radiation therapy (RT) during 1995 to 2012. Results There have been no failures in the pharyngeal axis. Relapse at initial neck sites of disease developed in 7 patients (8.2%). The median dose to these sites was 70 Gy (range, 63-70 Gy). Failure at neck sites without initial disease occurred in 4 patients (4.7%). The median dose was 54 Gy (range, 50-58.8 Gy). There were no contralateral failures in a small cohort of patients receiving unilateral treatment (n = 6). Percutaneous endoscopic gastrostomy (PEG) tube dependence at 12 months was 7.4%, and 2.5% at 3 years. Esophageal stricture developed in 5 patients (5.9%). Conclusion RT for HNCUP produces excellent locoregional control rates with acceptably low levels of late toxicity. Doses prescribed to sites of eventual failure did not vary significantly from those sites that were treated and remain in control.