Purpose: Radiation therapy áRTñ is a widely used form of treatment of head and neck cancers. In recent years, a number of patients with head and neck cancer treated with RT were noted to develop isolated enlargement of the submental lymph nodes áLNñ months to years after radiation therapy without signs of progression on follow up. The purpose of this study is to determine the relationship between frequency of submental LN enlargement in relation to RT fields, other interventions, and patient¢s outcome. The hypothesis is that the enlargement of submental LN is benign in nature.
Methods and Materials: Eighty-seven subjects were selected from a list of patients with head and neck cancer who received RT at the University of Florida from January 1995 to July 1999, had at least 2 cross-sectional studies áCT or MRIñ performed post RT and available for review and had at least 2 years of clinical follow up. Patients with lymphoma or previous surgical intervention in the submental region were excluded from the study. All cross sectional studies were reviewed, and the size and internal characteristics of the submental LN were documented. Primary site, tumor stage, radiation fields, as well as patient¢s outcome and surgical interventions were recorded.
Results: Enlargement of the submental LN following RT was seen in 9 á10.3%ñ patients after completion of RT. All 9 patients were treated with RT that was bilateral to the upper neck excluding the submental region. There was a statistical difference in size of submental LN between patients treated with RT bilateral to the upper neck excluding the submental region and the other radiation fields combined áp = .0289ñ. Seven patients are alive without disease, 1 patient died of inter-current disease and 1 patient died of disease at the primary site without evidence of nodal disease as demonstrated on a Thallium scan performed few days prior to patient¢s death. No correlation to surgical intervention, tumor stage or primary site was evident.
Conclusion: The incidence of enlargement of submental LN following RT to the upper neck is 10%. Patients treated with bilateral RT to the upper neck with exclusion of the submental region are at highest risk. Our study supports that the enlargement of the submental LN in this particular RT treatment group is benign in nature. We postulate that it may be due to reactive hyperplasia caused by alteration of the lymphatic drainage from the submandibular to the submental LN secondary to the RT. Enlargement of submental LN in other RT treatment groups should warrant further investigation.