Laminin, a glycoprotein component of basement membrane, and cathepsin B, a lysosome-derived proteinase, are thought to play a role in the complex process of tumor invasion and metastasis. This study evaluates the possible prognostic significance of laminin degradation and cathepsin B expression in Stage I (T1NO, T2NO) human non-small cell lung cancer. Archival, formalin-fixed, paraffin-embedded lung tissue from patients with documented Stage I non-small cell cancer was studied in a series of 31 patients (14 men, 17 women; ages 40-82 yr; mean age, 67 yr) by using polyclonal antibodies against laminin and cathepsin B. The immunoexpression of laminin was assessed with respect to a continuous versus discontinuous pattern, whereas that of cathepsin B was semiquantitated according to a four-tiered grading scale: 0, 0% positive cells; 1, 1 to 9%; 2, 10 to 49%; and 3, more than 50% positive cells. Cox proportional hazards models and Kaplan-Meler survival analysis were used to evaluate the association of possible risk factors, including laminin and cathepsin B, with survival. Univariate analysis looking at possible associations of survival with age, sex, histologic type, degree of tumor differentiation, and tumoral stage (T1NO, T2NO) did not show significant association. Likewise, degradation of laminin and immunoexpression of cathepsin B did not show significant association with survival. Although previous studies suggested improved survival with increased laminin expression and decreased survival with high expression of cathepsin B, the results applying to intrastage (Stage I) non-small cell cancer suggest that the expression of laminin and cathepsin B has little prognostic significance.