Metastatic lymph-node clearance from head and neck epidermoid carcinomas following radiotherapy

Although tumor clearance is a common criterion in assessing the impact of r adiotherapy (RT), it is not always reliable. Patterns of tumor clearance we re determined using 91 metastatic lymph nodes (LNs) from 51 patients with h ead and neck tumors treated by definitive RT (61-80 Gy) or preoperative RT (43-65 Gy). Clearance rate (CR) was estimated as a daily volume decrement e xpressed as a ratio to the pre-RT LN volume. CR was greater for the so-call ed radioresponsive nasopharyngeal subgroups and more poorly differentiated than those of oral cavity and well-differentiated respectively. Histologica lly, LNs that were removed following RT consisted mainly of fibrous tissues : necrotic tissues, and few cancer cells. There was no difference in CR bet ween the cancer-cell-positive group (n = 21) and the cancer-cell-negative g roup (n = 31). Although the CR may reflect inherent radiosensitivity of tum or cells, tumor persistence predicts the amount of oncologically inactive m aterials rather than that of remaining cancer cells.