Assessment of proliferation index with MIB-1 as a prognostic factor in radiation therapy for cervical cancer

Objectives. The relationship between the expression of murine monoclonal antibody MIB-1, which reacts with Ki-67 nuclear antigen, a marker for proliferating cells, and the prognosis of stage IIIb cervical cancer after radiation therapy was analyzed. Methods. A total of 67 patients with stage IIIb cervical cancer who had received radiation therapy were included in the retrospective study. The labeled streptavidin-biotin method was used for immunohistochemical staining of the MIB-1 protein. Results. In 32 patients showing a high MIB-1 index (percentage of cells labeled with MIB-1 greater than or equal to 26.4%), the cumulative 5- and 8-year survival rates were 75.8 and 61.5%, respectively, significantly better (P < 0.05) than those in 35 patients with a low MIB-1 index (<26.4%) (59.6 and 41.1%, respectively). Serum squamous cell carcinoma antigen levels, an index of the response to radiation therapy, decreased to less than or equal to2.0 ng/mL in 100 and 68% of patients in the high and low MIB-1 index groups, respectively (P < 0.05). Conclusion. These results indicate that MIB-1 antigen may be effective in predicting the sensitivity of cervical cancer to radiation therapy and stage IIIb cervical cancer prognosis. (C) 2000 Academic Press.