Proliferation of antigen MIB-1 in metastatic carcinoid tumours removed at liver transplantation: relevance to prognosis

Background Metastatic carcinoid tumours are difficult to manage. In spite of a multidisciplinary approach, including orthotopic liver transplantation, the recurrence rate is high with a poor prognosis. Histopathology generally fails to provide prognostic information, hence it is essential to try to identify markers of prognosis in these tumours before considering orthotopic liver transplantation. The MIB-1 antibody, which detects cell proliferative activity, has been shown to be a useful prognostic marker for a variety of neoplasms. Aims To assess the value of MIB-1 immunostaining as a prognostic marker of the duration to recurrence and the survival of patients undergoing orthotopic liver transplantation for metastatic carcinoid/neuroendocrine tumours of the liver. Methods Fourteen patients were included in the study. Formalin-fixed, paraffin-em bedded tissue sections of the tumours were stained with routine haematoxylin and eosin and chromogranin. The cell proliferative activity was assessed by MIB-1 antibody labelling using the immunoperoxidase method. Results were correlated with the time of tumour recurrence and the length of patients' survival after transplantation. Results No correlation was found between MIB-1 labelling index and age, gender, clinical and histological type of tumour (i.e. carcinoid, APUDOMA, secreting or non-secreting). The patients with higher MIB-1 indices (> 5%) showed a trend toward earlier recurrence and poorer survival than those with low MIB-1 indices (< 5%). The predictive value of a MIB-1 index of < 2 indicating patient survival of > 24 months was 83% (five out of six patients). Conclusions The correlation between MIB-1 index and patients' survival suggests that a high proliferative rate, as assessed by MIB-1 immunostaining, may detect those tumours with more aggressive biological behaviour. Prospective studies on a larger number of patients will be needed to determine if, in any individual tumour, this method will provide an additional parameter for a rational approach to therapy.