Judging prognosis in malignant melanoma of the skin. A problem of inference over small data sets.

Data was generated for 828 clinical stage 1 melanoma patients, divided into groups according to sex, tumor location, and tumor level for each of the 56 groups. Summary data, including the number of patients, number of patients dying as a result of melanoma, range of tumor thickness, mean and median tumor thickness, and mean length of follow-up of the surviving patients, are shown. Patients with melanoma of the palms and soles, subungual melanomas, and mucosal melanomas were excluded. A physician with a new melanoma patient could select the appropriate group for his or her patient, matched with respect to sex, location, and level, and then make a judgment regarding the prognosis, based on the survival experience of the group. In a few groups, the small numbers of patients provides only a rough impression of survival, but with many groups, a fair estimate can be made. The effectiveness of elective lymph node dissection was examined by creating 111 pairs of patients, matched by sex, level, location, and tumor thickness (to within +/- 12%), in which one member of the pair had an elective node dissection (ELND) and the other did not. There was no statistically significant difference between the survival of the two groups.