In a recent letter entitled "An Inaccuracy in an Otherwise Solid Study," Dr A. Bernard Ackerman¹ criticizes the statement by Kashani-Sabet et al² that "the role of [vascular invasion] in the prognostic assessment of malignant melanoma has remained controversial." It is the view of Dr Ackerman and his associates that vascular invasion by any melanoma is "virtually equivalent to metastasis."¹ He says that, except for a single statement in the literature saying that vascular invasion does "not influence prognosis significantly," he is unaware of any "statement to that effect anywhere."¹

Perhaps I can help. Clark et al,³ in their classic article on prognostic factors in melanoma, stated that "[t]wenty-three attributes [including vascular invasion] were tested for entry into [their] model. Six had independent predictive prognostic information." Vascular invasion was not among these; it dropped out from the multivariate analysis. More recently, using logistic regression, Barnhill et al⁴ examined 14 pathologic parameters, including vascular invasion, in melanomas from 548 patients. In their univariate analysis, vascular invasion showed prognostic significance, but in their multivariate analysis it again dropped out. Vollmer⁵ reviewed 54 reports of multivariate analyses of prognostic factors in melanoma; he found that only 3 of the studies showed vascular invasion to be significant, whereas 10 of them did not and 41 of them ignored it altogether. It follows that the statement by Kashani-Sabet et al² is correct and that Dr Ackerman's criticism is not justified.