Cytological Ki-67 in pancreatic endocrine tumours: an opportunity for pre-operative grading

The cytological Ki-67 expression measured on cytological samples collected by endoscopic ultrasonography-guided fine needle aspiration cytology (EUS-FNAC) may provide pre-operative indications for pancreatic endocrine tumours (PETs) management. The aim of our study was to assess reliability of Ki-67 expression measured on cytological samples obtained by EUS-FNAC in patients with PETs. Eighteen patients with PETs underwent EUS-FNAC before surgery. Ki-67 expression was measured on FNACs and on histological sections. Using a cut-off of 2%, percent agreement of Ki-67 expression on cytological and histological samples was 89% (k-statistic: 0.78, 95% confidence intervals (95% CI): 0.5, 1.0). Using cut-off values of 2 and 10%, percent agreement was 78% (k-statistic: 0.65, 95% CI: 0.3, 0.9). Ki-67 expression measured on cytological samples obtained by EUS-FNAC before surgery showed good agreement with that measured on histological samples.