PRIMARY CUTANEOUS MELANOMA - IDENTIFICATION OF PROGNOSTIC GROUPS AND ESTIMATION OF INDIVIDUAL PROGNOSIS FOR 5093 PATIENTS

Background. Numerous investigations have examined prognostic factors f or patients with primary cutaneous melanoma. However, only a few studi es have been published on the definition of prognostic groups. The fir st aim of the present study was to determine the relative importance o f different prognostic factors in a large collective study. The second aim was to define prognostic groups of patients based on combinations of prognostic factors and to define a model that allows the estimatio n of individual survival probability. Methods. Long term follow-up of 5264 patients with invasive primary cutaneous melanoma was performed f rom 1970 to 1988 at four German University Departments of Dermatology (Berlin-Steglitz, Munster-Hornheide, Tubingen, and Wurzburg). The mult ivariate Cox model was used to analyze 5093 patients, and 4371 patient s with complete information were included in a classification and regr ession tree analysis (CART). Results. Tumor thickness, sex, anatomic l ocation, and level of invasion were highly significant prognostic fact ors according to the multivariate analysis (P < 0.0001). However, hist ologic subtype and age influenced prognosis less significantly (P < 0. 05). The CART analysis resulted in 12 groups defined mainly by tumor t hickness, sex, and anatomic location, which were combined into five pr ognostic groups. The prognostic stratification defined by the five gro ups was superior compared with the standard TNM model. Ten-year surviv al rates of the five groups ranged from 97% to 14% (P < 0.0001), and a n equation was used to calculate individual survival probabilities bas ed on the significant factors of the Cox model. Conclusions. Considera tion of all significant prognostic factors of patients with primary cu taneous melanoma investigated in the present study allows for the defi nition of prognostic groups with a more reliable estimation of prognos is than by previous staging systems and also enables calculation of in dividual survival probabilities.