BETA(1) INTEGRIN EXPRESSION IN MALIGNANT-MELANOMA PREDICTS OCCULT LYMPH-NODE METASTASES

Background. Elective lymph node dissection for malignant melanoma is s till controversial. Experimental studies suggest that differential exp ression, activation, or both of PI integrins facilitate melanoma metas tases. However, the clinical significance of beta(1) integrin expressi on in human melanoma is unclear.Methods. We examined primary cutaneous melanomas from 76 patients undergoing elective lymph node dissection. We quantified the percentage of tumor area stained by pr integrin ant ibody with an image analyzer. Results. beta(1) integrin was expressed in all 23 primary tumors from patients with pathologically positive ly mph nodes (LNs) but in only 14 (26%) of 53 cases with pathologically n egative nodes (p < 0.001). No patients with beta(1) integrin-negative tumors had LN involvement, whereas 23 (62%) of 37 patients with beta(1 ) integrin-positive tumors had LN metastases (p < 0.001). Furthermore, 21 (91%) of 23 cases with LN metastases but only 4 (8%) of 53 cases w ithout had beta(1) integrin staining of 10% or more of tumor area (p < 0.001). Conclusions. Our study is the first to show a correlation bet ween expression of a molecular marker in the primacy cutaneous melanom a and likelihood of regional LN metastases. beta(1) immunostaining of 10% or more of tumor area reliably predicts patients most likely to ha rbor occult LN metastases and likely to benefit from ELND.