Sparing the Larynx and Hypopharynx With Radiotherapy for Squamous Cell Carcinoma of Unknown Primary Site and Predominant Adenopathy in Level IIA.

Abstract

PURPOSE/OBJECTIVE(S)\nThere is controversy about the need to target the mucosa of the larynx and hypopharynx during radiotherapy (RT) for squamous cell carcinoma of unknown primary site (SCCA-UP). By 1997, the policy in our department was to target only the oropharynx and nasopharynx in patients with SCCA-UP metastatic to the level II cervical nodes. The purpose of this study is to report the rate of cancer recurrence in the larynx or hypopharynx using an approach that excluded these areas from the RT target volumes.\n\n\nMATERIALS/METHODS\nWe reviewed the medical records of patients who met the following inclusion criteria: received RT in our department for SCCA-UP between January 1, 1997, and December 31, 2019; no history of surgery that could disrupt the cervical lymphatics; predominant adenopathy in level IIA; and neck stage N1-2c. We excluded N3 because the incidental dose to the larynx and hypopharynx is usually high in patients with a > 6-cm nodal conglomerate. We calculated the following from the date of the last RT fraction: mucosal control to the date of first recurrence in a mucosal site in the head and neck; regional control with or without distant control to the date of first recurrence in ipsilateral or contralateral neck nodes with or without distant disease; distant control to the date of first documented metastatic lesion most likely originating from SCCA-UP; relapse-free survival to the date of recurrent disease at any site or death; cause-specific survival to the date of death due to SCCA-UP; and overall survival to the date of death from any cause.\n\n\nRESULTS\nThe study population included 50 patients with a median follow-up after RT of 7.1 years. No patient developed recurrent cancer in a mucosal site (0/50), 2% (1/50) developed a neck recurrence in a high-dose area with synchronous distant metastases, and 2% (1/50) developed distant metastases with no evidence of local or regional recurrence. At most recent follow-up, 70% (35/50) of patients were alive without evidence of recurrent SCCA-UP (NED), 4% (2/50) died of recurrent cancer, 22% (11/50) died of intercurrent disease (DID), and 4% (2/50) died of unknown causes (unknown).\n\n\nCONCLUSION\nWhen delivering RT for SCCA-UP metastatic predominantly to level IIA, it is not necessary to target the mucosa of the larynx or hypopharynx. The extent to which the incidental RT dose to these areas contributes to cancer control is not evaluated in this study.