We compared tumor grade and DNA content with expression of E-cadherin (E-CD), a cell adhesion molecule associated with cell-cell and cell-matrix interaction, leukocyte function, and tumor invasion and metastases, on 56 prostate carcinoma needle biopsies. The findings were correlated with final pathologic stage at subsequent prostatectomy, preoperative serum prostate-specific antigen level and further development of metastases during an initial 2.4-yr mean clinical follow-up period (range 0.5 to 5.5 yr). E-CD expression (uvomorulin, L-CAM, cell CAM 80/120, ARC-1, Sigma, St. Louis, MO) was measured by double-linked immunoalkaline phosphatase immunohistochemistry quantified with a the Roche RPW image analyzer (Roche Image Analysis Systems, Elon College, NC). DNA ploidy was determined on formalin-fixed, paraffin-embedded Feulgen-stained 5-microns tissue sections of the narrow-bore initial prostate carcinoma biopsies with the Roche RPW image analyzer. The 51% mean positive area E-CD expression in the group of 56 adenocarcinomas was significantly less than the 76% expression level for 15 normal control prostate tissues (P < 0.001). E-CD expression was also decreased in aneuploid (39%) versus diploid tumors (54%, P < 0.001); and in high-grade (44%) versus low-grade lesions (54%; P < 0.01). The 44% E-CD expression level in patients with metastases was lower than the 52% level in the nonmetastatic cases, but this finding was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)