Lymph node metastases from laryngeal and pharyngeal carcinomas--calculation of burden of metastasis and its impact on prognosis.

A total of 1069 patients, 739 with newly diagnosed laryngeal and 330 with pharyngeal cancer, were seen at the Centre for Head and Neck Cancer, Odense University Hospital during the period 1965-1992. Of those with laryngeal carcinoma, 1% (5/499) of the glottic and 29% (68/232) of the supraglottic cases had primary lymph node metastases. The frequency of metastases in patients with primary endolaryngeal tumours was highest at the inlet of the larynx--38%--decreasing gradually distally to 1% at the level of the vocal cords. Metastases occurred among patients with pharyngeal carcinoma in 66% (218/330). All patients received primary radiotherapy, except for the 10 who were subjected to surgery. The calculation of the burden of lymph node metastases was based on the volume formula of an ellipse, and could be carried out on 280 of the 291 patients with metastases. The calculated volumes ranged from 1-1413 cm3. These were divided into 3 groups according to size. A Cox multivariate regression analysis, using crude and disease specific survival as endpoints, revealed the burden of metastasis to be an independent, prognostic factor.