Regional Lymph Node Irradiation

Abstract

When the lymph ondes are clinically negative (NO) and the risk of subclinical disease is 10%–15% or greater, the lymph nodes are included in the treatment portals and receive a minimum dose equivalent to 4500 cGy over 4½ weeks. In some clinical situations, the first-echelon nodes receive a much higher dose incidental to irradiation of the primary lesion. In the treatment portals used for cancers of the oropharynx, larynx, and hypopharynx, most of the high-risk neck nodes are encompassed by slight enlargement of the portals used to include the primary lesion. The decision to use elective lymph node irradiation depends on several factors:

• 1. Primary site and its relative density of capillary lymphatics

• 2. Risk of bilateral subclinical disease

• 3. Histologic grade and vascular space invasion

• 4. Depth of invasion and size of the primary lesion

• 5. Difficulty of neck examination

• 6. Relative morbidity for extending the lymph node coverage related to the risk of subclinical disease

• 7. Likelihood that the patient will return for frequent follow-up examinations

• 8. Suitability of the patient for a radical neck dissection should tumor appear in the neck