Parasympathetic neurogenesis is strongly associated with tumor budding and correlates with an adverse prognosis in pancreatic ductal adenocarcinoma

OBJECTIVE: To investigate the frequency of parasympathetic neurogenesis and determine its association with tumor budding and prognosis in pancreatic ductal adenocarcinoma (PDAC). METHODS: Parasympathetic neurogenesis was defined as the distribution of abnormal parasympathetic nerves in the stroma tissue. Staining of vesicular acetylcholine transporter (VAChT), as a marker for parasympathetic neurogenesis, was performed on a representative specimen of the tumor for 59 PDAC patients with available clinical, pathologic, and follow-up information. Three specimens containing normal pancreatic tissues were stained in parallel. The number of parasympathetic nerve fibers was counted in five high-power microscopic fields (5×0.785 mm(2)). Cut-off values were calculated by receiver operating characteristic curve analysis. RESULTS: VAChT-positive parasympathetic nerve fibers were not seen in the stroma of 3 cases of normal pancreatic tissues. In 59 PDAC cases, the range of parasympathetic neurogenesis was 4-38 fibers/(5×0.785) mm(2), with a median of 18 fibers/(5×0.785) mm(2). Patients with parasympathetic neurogenesis >15 fibers/(5×0.785) mm(2) were defined as the high-density group (39 patients, 66.1%), and those with parasympathetic neurogenesis 15 fibers/(5×0.785) mm(2) as the low-density group (20 patients, 33.9%). The high-density group had a higher occurrence of tumor budding (P=0.001) and a higher rate of early recurrence (P=0.035). Parasympathetic neurogenesis appeared to be an independent adverse prognostic factor [hazard ratio (HR)=2.45, 95% confidence interval (95% CI): 1.25-4.81, P=0.009], in addition to American Joint Committee on Cancer (AJCC) stage (P=0.010) and tumor budding (P=0.009). CONCLUSIONS: Parasympathetic neurogenesis is strongly associated with tumor budding and correlates with an adverse prognosis in PDAC.