DNA-PLOIDY ABNORMALITIES ARE A REFLECTION OF THE METASTATIC POTENTIALOF MALIGNANT-MELANOMA - MICROFLUOROMETRIC DNA ANALYSIS

Using DAPI (4',6-diamidino-2-phenglindole)-DNA microfluorometry, we ex amined the nuclear DNA-ploidy abnormalities of 15 primary malignant me lanomas and their 20 corresponding metastases, They all presented the aneuploid DNA histographic pattern. When the DNA index value was calcu lated as the reflection of DNA-ploidy abnormalities, it was found to b e significantly higher in the metastases (2.07 +/- 0.50) than in the p rimary tumors (1.76 +/- 0.50) (p < 0.01), Sixteen (80%) of the metasta tic tumors had a higher DNA index value than their primary tumors, whe reas the remaining four (20%) had a lower value, The difference in the DIVA index values between the primary and metastatic tumors did not c orrelate to any other conventional prognostic variables (e.g. histolog ic type, level, and thickness), When we added 15 non-metastatic melano mas to the above 15 primary melanomas and evaluated the predictors for metastasis using multivariate stepwise logistic regression analysis, the DNA index value of the primary melanomas was found to be the most reliable risk factor, These results suggest that primary melanoma cell populations, having high DNA index values, are usually responsible fo r subsequent metastasis, and that hence, DNA-ploidy abnormalities of p rimary melanomas are likely to provide useful information for patient potential with regard to metastasis.