A MOLECULAR EPIDEMIOLOGIC APPROACH TO THE STUDY OF EXPRESSION OF A METASTASIS MARKER IN PRIMARY MELANOMAS AND ITS CORRELATION WITH INDIVIDUAL PATIENTS RISK OF RECURRENCE OR METASTASIS

Tumour cells in malignant melanomas express molecules associated with tumour progression; however, up until now, no marker has been able to identify the tumour cells from which metastases are derived. It has re cently been shown that in human melanoma cell lines, populations expre ssing peanut agglutinin (PNA)-binding glycoproteins are able to genera te metastases, and that such cells do exist in primary human melanomas , their presence being associated with the degree of local invasion th at governs the metastasis risk. To further investigate the correlation between the expression of PNA-binding glycoconjugates by cells from p rimary melanomas and the patient's individual risk of recurrence or me tastasis, a molecular epidemiological approach employing histochemical techniques within a case-control design was developed. The main objec tive of this study is to determine whether an histochemical staining w ith the lectin PNA of cells in the primary lesion is associated with a n increased risk of local recurrence of metastasis, and with survival, independently of Breslow's tumour thickness. The study comprises the comparison of the PNA labelling index and of the type and intratumour location of the staining as a function of clinical outcome in two matc hed series of patients with known clinical outcome: patients who had d ied at 5 years and patients alive at 5 years (to assess association wi th survival), and patients who experienced a recurrence within the fir st 5 years and patients alive without recurrence at 5 years (to assess association with risk of recurrence). A matched case-control design w as used with a variable number of controls matched to each case. Apart from age (+/-5 years), sex and centre where diagnosis was made, match ing was made on histogenetic type and primary tumour thickness (four c ategories being considered: <0.75, 0.76-1.5, 1.513 and >3 mm).