Distribution of non-diploid flow-cytometric DNA indices and their relation to the nodal metastasis in squamous cell carcinomas of the head and neck

Abstract

Squamous cell carcinomas of the head and neck (HNSCC) evolve from diploid epithelial cells of the mucosa. At the time of diagnosis about two thirds of clinically diagnosed HNSCC are non-diploid according to flow-cytometric (FCM) analysis, indicating that during tumour progression there must be an acquisition and accumulation of chromosomal aberrations. At diagnosis one third to one half of HNSCC have clinically positive neck nodes. The objective of the present study was to see whether the progression to a metastatic phenotype is reflected in the distribution of FCM DNA ploidy in node-negative and node-positive HNSCC. The series comprised 200 patients with HNSCC. Tumour samples were obtained from diagnostic biopsies or primary surgery. A multistep preparation method and propidium iodide staining of nuclear DNA content was used for FCM. One hundred and forty one (71%) of the tumours were non-diploid. Only two tumours were hypodiploid (DNA index 0.73 and 0.93, respectively). Ten of the tumours exhibited two non-diploid stem cell lines. The frequency of non-diploidy in node-negative tumours was 65% and in node-positive ones about 80%. The frequency distribution of non-diploid DNA indices clustered in the hypotetraploid region (with a modal value of 1.71-1.74) and did not differ between node-negative and node-positive tumours. The hypothesis that the disposition to metastasis is reflected in the frequency distribution of non-diploid DNA indices could thus not be verified.