Prognosis of stage I melanoma of the skin was evaluated in 747 previously untreated patients observed by the WHO Collaborating Centres for Evaluation of Methods of Diagnosis and Treatment of Melanoma from September 1967 to September 1975. The mean follow-up period of these patients was 8.9 years. Sex, maximum diameter of melanoma, elevation on skin surface, histologic type, levels of invasion and maximum tumor thickness were found to be significantly related to survival when considered one by one. However, multifactorial analysis showed that sex and maximum thickness only had a significant impact on survival of stage I melanoma patients.
The effect of sex was not evident in patients with maximum tumor thickness not exceeding 2 mm (81 % 5-year survival for males and 87% for females and a p value >0.05), while females did significantly better (p <10−4) when maximum thickness of primary was over 2 mm.