Pancreatic intraepithelial neoplasia in the background of invasive ductal carcinoma of the pancreas as a prognostic factor

Aims: Of the recognized precursor lesions of pancreatic adenocarcinoma, pancreatic intraepithelial neoplasia (PanIN) is the most common form. However, little is known about the relationship between the grade of PanIN and prognosis for patients with invasive ductal carcinoma. Methods and results: In 124 patients with invasive ductal carcinoma, we examined the grade and number of PanIN lesions in all slides of resected pancreas. The prevalence rates of PanIN-1A, PanIN-1B, PanIN-2 and PanIN-3 were 86%, 84%, 57% and 30%, respectively. We allocated PanIN-2 and PanIN-3 cases into a PanIN-high group, and cases showing PanIN-1A, PanIN-1B or absence of PanIN into a PanIN-low group. In clinicopathological analysis, PanIN-high status was significantly correlated with the number of PanIN lesions (P < 0.0001). Disease-free and overall survival were statistically better in the PanIN-high group than in the PanIN-low group (P = 0.0005 and P = 0.0003). Univariate and multivariate analyses revealed that tumour size and PanIN-low status were statistically significant factors for a poorer prognosis (P = 0.042 and P = 0.007). Conclusions: In a pathological examination, it is important to evaluate the grade and number of PanINs in assessing the prognosis of pancreatic cancer.