Representativity of Incisional Biopsies for the Assessment of Flow Cytometric DNA Content in Head and Neck Squamous Cell Carcinoma

DNA flow cytometry studies of squamous cell carcinoma of the head and neck have shown that patients with diploid tumours have favourable prognoses, whereas the outcomes of those with DNA aneuploid tumours are poor. DNA flow cytometry is therefore increasingly used as an integral part of diagnostic procedures. To evaluate how representative biopsies predict the DNA ploidy of oral carcinomas, incisional biopsies taken pretherapeutically from 256 tumours were compared with the corresponding surgical resection specimens. Sixty-six tumours exclusively displayed cells with flow cytometrically diploid DNA content in both the biopsy and the subsequent resection specimen, while 182 carcinomas expressed DNA aneuploid tumour cell lines in matched samples. There were only 8 tumours (3.1%) with heterogeneity in the DNA ploidy status between the biopsy and the resection specimen. These results emphasise the usefulness of incisional biopsies to reliably prognosticate the DNA ploidy status of oral carcinomas.