Formula predicting survival in patients with invasive cutaneous malignant melanoma.

Popescu et al. (Mayo Clin Proc., 65 (1990) 1293-1302) reported survival data in 107 patients who were diagnosed as having malignant melanoma during the years 1950-1985. Survival was evaluated by using the Kaplan-Meier method. A microcomputer program in BASIC for predicting the survival probability after diagnosis in patients with invasive cutaneous malignant melanoma is designed. A formula used in this program is derived from the survival data reported by Popescu et al. A mathematical model of generalized lognormal distribution and a computer program previously published by the author are employed in this study. Analysis of the computer-assisted predicted values and the data reported by Popescu et al. indicates that the program is accurate and reliable with a close agreement in expressing survival probability as a function of time after diagnosis. The computer-assisted predictive formula can determine the relationship between the time and the survival probability, and may be of value for prognostic evaluation of patients. The mathematical model representing the generalized lognormal distribution may be used as a method of parametric analysis of survival data of estimates determined by the nonparametric product-limit method of Kaplan-Meier in certain biological phenomena.