Evaluation of hepatocellular carcinoma aggressiveness by a panel of extracellular matrix antigens. Invasion and metastasis requires a series of interactions between malignant cells and the extracellular matrix (ECM). Antigen markers that relate to these interactions were evaluated for prognostic correlation in human hepatocellular carcinoma. Basement membrane type IV collagen (cIV), type IV collagenase (cIVase), laminin, and laminin receptors (LRs)--all ECM antigens previously proposed to be modulated in association with tumor aggressiveness--were immunohistochemically investigated in 30 cases of hepatocellular carcinomas (HCCs). The pattern of antigen expression was correlated with 1) 36 months' clinical follow-up and 2) the pathologic grade. As a means of estimating the proliferation fraction, an additional antigen, Ki67, was also studied in this series. There were major differences in the distribution of cIV and laminin, and in the quantity of cIVase-, LR-, and Ki67-positive cells associated with grade and prognosis. A smaller quantity of cIV and laminin and a higher number of cIVase-, LR-, and Ki67-positive cells were detected in the poorly differentiated compared with the well-differentiated HCCs. The tumors with lower immunoreactivity for cIV and laminin components accompanied by a higher number of cIVase-, LR-, and Ki67-positive cells fall into a group with the poorest overall survival (P less than 0.006). The panel of antigens is proposed as a useful prognostic tool for evaluating HCC tumor aggressiveness. 