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

Abstract

There is controversy about the need to target the mucosa of the larynx and hypopharynx during radiation therapy (RT) for squamous cell carcinoma of an 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 was to report the rate of cancer recurrence in the larynx or hypopharynx using an approach that excluded these areas from the RT target volumes. The inclusion criteria for this study were 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. The study population was comprised of 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. When 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.