Background: Ampullary early stage cancer (early CA) potentially harbors lymphovascular invasion; there are few data on markers that could differentiate adenoma and early CA.
Aim: To investigate those markers, we compared the tumor diameter and Ki-67 expression in endoscopy biopsy specimens of adenoma with those of early CA.
Methods: Patients on whom endoscopic papillectomy (EP) was performed (n = 35) with histopathologically proven adenomas and with low/high grade dysplasia and early CA were studied. We made pre-procedure evaluations of ampullary tumors by using endoscopic ultrasonography (EUS) and transpapillary intraductal ultrasonography. Tumor diameter was measured by EUS. Endoscopic biopsy using immunostaining of Ki-67 labeling index (LI) prior to EP were evaluated.
Results: The areas under the receiver-operating characteristic (AUROC) curves for tumor diameter and Ki-67 expression were 0.824 and 0.873, respectively. Cut-off values calculated based on AUROC data were 15 mm in tumor diameter and 32 cells/high-power field (HPF) in Ki-67. Early CA (n = 11) was diagnosed by using a cut-off value for tumor diameter in 8 out of 11 patients (sensitivity 72.7 %, specificity 66.7 %, accuracy 68.6 %). Significant infiltration of the major duodenal papilla by Ki-67 positive tumor cells (>31/HPF) was recognized in 8 of the 11 patients with early CA (sensitivity 100 %, specificity 54.2 %, accuracy 62.9 %).
Conclusions: Observation of tumor diameter and Ki-67 LI would be helpful for safety EP. EP should not be indicated for ampullary tumors more than 15 mm in diameter and/or Ki-67 LI 31/HPF.