Background: Margin status is one of the strongest prognosticators after resection of pancreatic ductal adenocarcinoma (PDAC). The clinical significance of pancreatic intraepithelial neoplasia (PanIN) at a surgical margin has not been established. Methods: A total of 208 patients who underwent R0 resection for PDAC between 2004 and 2008 were selected. Intraoperative frozen section slides containing the final pancreatic parenchymal transection margin were evaluated for presence or absence, number, and grade of PanINs. Data were compared to clinicopathologic factors, including patient survival. Results: PanIN lesions were present in margins in 107 of 208 patients (51.4%). Median number of PanINs per pancreatic resection margin was 1 (range, 1-11). A total of 72 patients had PanIN-1 (34.6%), 44 had PanIN-2 (21.1%), and 16 had PanIN-3 (7.2%) at their margin. Overall median survival was 17.9 (95% confidence interval, 14-21.9) months. Neither the presence nor absence of PanIN nor histological grade had any significant correlation with important clinicopathologic characteristics. There were no significant survival differences between patients with or without PanIN lesions at the resection margin or among patients with PanIN-3 (carcinoma in situ) versus lower PanIN grades. However, patients with R1 resection had a significantly worse outcome compared with patients without invasive cancer at a margin irrespective of the presence of PanIN (P = 0.02). Conclusions: The presence of PanINs at a resection margin does not affect survival in patients who undergo R0 resection for PDAC. These results have significant clinical implications for surgeons, because no additional resection seems to be indicated when intraoperative frozen sections reveal even high-grade PanIN lesions.
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