P90 EXCEEDING RATE AS A PROGNOSTIC FACTOR PRIMARY MALIGNANT-MELANOMA OF THE SKIN - A DNA IMAGE CYTOMETRIC STUDY

OBJECTIVE: To study the prognostic value of DNA image cytometry in pri mary skin melanomas. STUDY DESIGN: DNA image cytometry was per formed on 62 stage I, Clark level II-V, primary skin melanomas. The DNA histo grams were classified into three categories (diploid, nondiploid and a neuploid) according to the percentages of cells with higher-than-diplo id and higher-than-twice-the-diploid DNA content (the P90 and 2P90 exc eeding rates [ERs]). The prognostic value of P90ER, 2P90ER, type of DN A histogram, melanoma thickness, Clark level, and patient age and sex were analyzed for disease-specific survival with Cox's stepwise propor tional hazards model. RESULTS: Aneuploid DNA histograms were as common in thin as in thick melanomas. Melanoma thickness and P90ER had progn ostic value in univariate analysis, but in the multivariate analysis o nly P90ER had independent and significant prognostic value. CONCLUSION : Aneuploidy is a common feature of malignant melanoma, and it is as c ommon in thin as in thick melanomas. P90ER has more prognostic value t han the type of DNA histogram. The prognostic value of P90ER as compar ed with melanoma thickness should be studied further.