Immunohistochemical study of cathepsin B. Prognostic significance in human lung cancer

Background. The concentration of cysteine proteinase cathepsin B has been shown to be elevated in association with malignancy or metastatic potential of human and rodent tumors, but its prognostic value for human lung cancer remains undetermined. Methods. Using a polyclonal antibody, immunohistochemical analyses of cathepsin B were performed on paraffin embedded sections of tumors obtained surgically from 108 patients with non‐small cell lung cancer (49 squamous cell carcinomas, 59 adenocarcinomas). The immunohistochemical expressions of cathepsin B in the tumors were compared with patient survival. Results. Higher grade expression of cathepsin B was associated significantly with shorter survival in nonsmall cell lung cancer (P < 0.01), in squamous cell carcinoma (P < 0.05), and in adenocarcinoma (P < 0.01). A similar result also was seen in Stage I non‐small cell lung cancer (P < 0.05). Conclusions. The authors concluded that the immunohistochemical staining pattern of cathepsin B may be a useful predictor of survival for human lung cancer.