COMPLEX KARYOTYPES IN FLOW CYTOMETRICALLY DNA-DIPLOID SQUAMOUS-CELL CARCINOMAS OF THE HEAD AND NECK

In squamous cell carcinoma of the head and neck (SCCHN), DNA ploidy as determined by flow cytometry (FCM) has been found to yield prognostic information but only for tumours at oral sites. Cytogenetic findings have indicated complex karyotype to be a correlate of poor clinical ou tcome. In the present study, 73 SCCHN were investigated with the two t echniques. Aneuploid cell populations were identified in 49 (67%) case s by FCM but in only 21 (29%) cases by cytogenetic analysis. The chrom osome index (CI), calculated as the mean chromosome number divided by 46, was compared with the respective DNA index (DI) obtained by FCM in 15 tumours, non-diploid according to both techniques, DI being system atically 12% higher than CI in this subgroup. Eight (33%) of the 24 tu mours diploid according to FCM had complex karyotypes, three of the tu mours being cytogenetically hypodiploid, three diploid and two non-dip loid. The findings in the present study may partly explain the low pro gnostic value of ploidy status as assessed by FCM that has been observ ed in SCCHN. In addition, we conclude that FCM yields information of t he genetic changes that is too unspecific, and that cytogenetic analys is shows a high rate of unsuccessful investigations, thus diminishing the value of the two methods as prognostic factors in SCCHN.