DNA index and % S phase fraction in posterior uveal melanoma: a 5 year prospective study of fresh tissue using flow cytometry.

In many different solid tumours the DNA content of cells has been reported to be associated with malignancy. With one exception, studies using flow cytometry to estimate cellular DNA in uveal melanoma have used archival material. We report the findings of a prospective study using fresh uveal melanoma where the DNA index (DI) and percentage of cells in S phase (%SPF) have been determined by flow cytometry in 51 patients with a minimum follow-up of 5 years. Forty-one (80%) of the tumours were large, 9 (18%) were medium and only 1 was small. Eight (16%) were epithelioid tumours, 41 (80%) were mixed cell and only 2 were spindle B cell tumours. Twenty-seven tumours were diploid, of which 10 (37%) developed metastases. Of the 24 aneuploid tumours, metastases developed in 6 (25%). The median %SPF was significantly reduced in patients with diploid tumours compared with aneuploid tumours (p < 0.0001), but there were no significant differences in %SPF between tumours associated with or without metastatic disease. The DI and %SPF were not significantly associated with the operation performed, cell morphology, tumour size or location. Neither %SPF nor aneuploidy was associated with a poor prognosis. Our results suggest that the estimation of DI or %SPF by flow cytometry is of little value in predicting survival from uveal melanomas after a minimum follow-up of 5 years.