Abstract: Establishing prognosis proves particularly difficult with neuroendocrine tumours (NETs) as a benign looking histology can be associated with a malignant behaviour. In order to identify prognostic factors we examined 44 gastrointestinal and pulmonary, paraffin‐embedded NETs histologically and immunohistochemically. DNA‐image‐cytometry was used to examine 40 of these. We found that poor differentiation (corresponding to a Soga and Tazawa type D) and infiltrative growth correlated with a poorer prognosis. Moreover, parameters determined by diagnostic DNA cytometry like the 5c‐exceeding rate, the 2c‐deviation index, DNA‐grade of malignancy, DNA‐entropy and the type of DNA histogram were found to be of prognostic relevance. Morphometric parameters like the form factor and the mean nuclear area were relevant for survival, tumour recurrence and metastasis. However, in the multivariate analysis the only independent risk factor was the histological differentiation. The 5c‐exceeding rate is a good objective risk factor, which can be used particularly in cases in which only a fine needle biopsie is available. Direct comparison of the histology and the 5c‐exceeding rate in the multivariate analysis suggests that the 5c‐exceeding rate taken as sole prognostic factor might be of higher prognostic relevance than the histology but larger studies are needed to confirm this.
