Head and neck squamous cell carcinoma from an unknown primary site

The purpose of this study is to present our experience treating patients with squamous cell carcinoma (SCC) from an unknown head and neck primary site and to determine whether a policy change eliminating the larynx and hypopharynx from the radiotherapy (RT) portals has impacted outcome.

One hundred seventy-nine patients received definitive RT with or without a neck dissection for SCC from an unknown head and neck primary site. RT was delivered to the ipsilateral neck alone or both sides of the neck and, usually, the potential mucosal primary sites. The median mucosal dose was 5670 cGy. The median neck dose was 6500 cGy. One hundred nine patients (61%) received a planned neck dissection.

Mucosal control at 5 years was 92%. The mucosal control rate in patients with RT limited to the nasopharynx and oropharynx was 100%. The 5-year neck-control rates were as follows: N(1), 94%; N(2a), 98%; N(2b), 86%; N(2c), 86%; N(3), 57%; and overall, 81%. The 5-year cause-specific survival rates were as follows: N(1), 94%; N(2a), 88%; N(2b), 82%; N(2c), 71%; N(3), 48%; and overall, 73%. The 5-year overall survival rates were as follows: N(1), 50%; N(2a), 70%; N(2b), 59%; N(2c), 45%; N(3), 34%; and overall, 52%. Eleven patients (7%) developed severe complications.

RT alone or combined with neck dissection results in a high probability of cure with a low risk of severe complications. Eliminating the larynx and hypopharynx from the RT portals did not compromise outcome and likely reduces treatment toxicity.