Regression thickness as prognostic factor in thin cutaneous malignant melanomas

BACKGROUND: The diagnosis of thin cutaneous malignant melanomas has been increasingly more frequent. These lesions, initially associated with excellent prognosis, have presented recurrence or metastases and sometimes have been fatal. Many variables have been studied and, although none of them has explained this behaviour, regression and its possible negative impact have been focused on recently. According to some authors, late regression bears major relevance in the prognosis. OBJECTIVE: To correlate the maximum regression thickness of thin cutaneous malignant melanomas with disease-free survival time. MATERIALS AND METHOD: Retrospective study of 84 cases of thin cutaneous malignant melanomas. The criteria of Kang et al. (1993) for identification and evolutionary classification (early, intermediate and late) of the regression were applied. RESULTS: Regression (in any phase) was observed in 70 out of 84 thin cutaneous malignant melanomas (83.3%), and 30 cases (35.7%) showed late regression. The maximum regression thickness measurement ranged from 0.16 to 1.53 mm. Disease-free survival time ranged from 17 days to 108 months. Five cases (5.9%) had an unfavorable outcome, from which three were in situ melanomas. There was no correlation between the studied variables (p > 0.05). DISCUSSION: The meaning of regression in thin cutaneous malignant melanomas is controversial, probably due to the different methods applied in the few studies carried out about the subject and the wide variety of size and composition of the samples. There is no medical consensus as to a standardized regression measurement system, which partially explains the controversial results obtained to date. CONCLUSIONS: There was no statistical correlation between regression thickness in thick cutaneous melanomas and disease-free survival time (p > 0.05). Future studies with wider samples may contribute to a better understanding of this phenomenon.

Melanoma; Spontaneous neoplastic regression; Prognosis; Disease-free survival analysis

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