Stromelysin-3 expression in noninvasive and invasive neoplasms of the urinary bladder

Stromelysin-3 (ST-3) is a protease frequently expressed by fibroblasts surr ounding invasive carcinomas. Based on its expression in some cases of breas t carcinoma-in-situ, it has been thought to indicate a higher likelihood fo r subsequent invasion in preinvasive lesions. Carcinoma-in-situ (pTis) and noninvasive papillary tumor (pTa) of the urinary bladder are preinvasive le sions with an uncertain potential to become invasive. We studied the expres sion of ST-3 in pTis, pTa, and invasive bladder tumors to see whether it ha d an association with any established histopathologic variables and whether its expression might be an indicator of incipient invasion in the preinvas ive lesions. Twenty-seven pTis, 27 pTa tumors, and 56 invasive bladder carc inomas were studied for ST-3 expression with immunohistochemistry and, in s elected cases, with in situ hybridization. Staining for ST-3 was evaluated semiquantitatively. None of 27 pTis lesions, 4 of 27 pTa tumors, and 41 of 56 (73.2%) invasive carcinomas were positive for ST-3. Statistically signif icant associations were found in the invasive carcinomas between ST-3 expre ssion and lymphatic vessel invasion, an infiltrative invasive pattern, and invasion into at least the muscle layer (pT2,3,4 v pT1). The expression of ST-3 in frankly invasive tumors was associated with a more aggressive tumor phenotype. its expression in a small subgroup of pTa lesions may be indire ct evidence that some tumors diagnosed as pTa have invasive potential. Copy right (C) 2000 by W.B. Saunders Company.