Prognostic and biological significance of cytokeratin 19 in pancreatic endocrine tumours

Aim: The prognosis of well-differentiated pancreatic endocrine tumours (PETs) is difficult to establish on a histological basis. The expression of cytokeratin (CK19) has recently been proposed as an indicator of unfavourable outcome. However, this finding still needs to be verified and to be compared with more frequently used prognosticators such as proliferative indices, vascular and/or perineural invasion. The aim of this study was to evaluate the prognostic value of CK19 expression in PETs. Methods and results: One hundred and forty-five PETs were studied using two different anti-CK19 monoclonal antibodies (BA17 and RCK108). The results were statistically compared with proliferation markers, vascular and perineural invasion and the presence of metastases. On univariate analysis, CK19 immunoreactivity correlated with prognosis only when it was detected with the RCK108 antibody and only in the whole group of PETs and in insulinomas. Conversely, it did not predict survival in non-functioning neoplasms. Ki67 index, mitotic count, vascular and perineural invasion were all statistically correlated with prognosis. On multivariate analysis, only the Ki67 index and metastases were independent prognosticators. Conclusions: CK19 expression correlates with patient survival only when detected with the RCK108 antibody and mainly in insulinomas. Ki67 index and metastases represent the only two independent predictors of survival.