SSTR4 and neoplasm: There were no differences in positivity rates and SST4 expression levels among the different BP-NEN entities, but SST4 expression varied significantly among GEP-NEN with different localisations of the primary tumour (χ2 test: p < 0.001; Kruskal–Wallis test: p < 0.001) (Fig. 2A and B).