Cellular apoptosis, proliferation and bcl-2 Bax expression in colorectal carcinoma and their association with tumor prognosis

OBJECTIVE: To investigate the relationship between cellular apoptosis, proliferation and bcl-2/bax expression in the tissue of colorectal carcinoma and biological behavior of the tumor. METHOD: The apoptotic cells index (AI) in situ were identified by the terminal deoxynucleotidyl transfer-mediated dUTP-biotin nick end labeling (TUNEL) and immunohistologic staining for Ki-67 proliferation index (KI), bcl-2/bax protein expression was performed on archival material from 77 adenocarcinomas. RESULT: The mean AI and KI were 5.3/45.4 in early stage cancer, 5.6/48.7 in non-metastatic cancer, 6.6/55.3 in advanced cancer and 8.9/60.1 in cancer with distant metastasis respectively. There was a positive relationship between the AI and KI in each specimen. bcl-2 and bax was expressed as 54.5%, 74% in carcinoma and highly differentiated carcinoma. In the univariate analysis, significantly longer survival time was observed in the subgroup of bcl-2 positive carcinoma with low AI. In the multivariate analysis, tumor stage, tumor type, KI, and bcl-2 expression were independent risk factors for prognosis. CONCLUSION: The data indicate that abnormally exchanged AI/KI, bcl-2/bax expression appears to be an event associated with tumor progression and apoptosis might also reflect the proliferative activity of human colorectal carcinoma.