The expression of proteolytic enzymes at the dermal invading front of primary cutaneous melanoma predicts metastasis.

The expression of three proteinases Cathepsin B (Cath. B), Cathepsin D (Cath. D) and Collagenase IV (Coll. IV) has been retrospectively analyzed within an immunohistochemical study on routinely fixed, paraffin embedded tissues from 147 primary cutaneous melanomas belonging to the classes pT3 and pT4. The development of these melanomas has been followed for at least five years. We compared the expression of these proteolytic enzymes in tumors that metastized during the follow-up-period with that in tumors that did not metastize. The expression at the dermal invading front of the tumors showed higher prognostic values (Cath. B chi 2 = 40.03, p < 0.001; Cath. D chi 2 = 90.95, p < 0.001; Coll. IV chi 2 = 44.46, p < 0.001) than the overall expression of these enzymes (Cath. B chi 2 = 5.63, p = 0.018; Cath. D chi 2 = 6.21, p = 0.010; Coll. IV chi 2 = 6.57, p = 0.010). The distribution of protease-expression inside the tumor turned out to be important for the prognostic value, which might also lead to higher prognostic confidence when applied to other tumors.