Introduction : The standard therapy for “Resectable” (according to JPS 7th Edition R) pancreatic ductal adenocarcinoma (PDAC) is upfront surgery followed by adjuvant chemotherapy and there is no evidence for the neoadjuvant treatment. In this study, the risk classification for patients with R-PDAC who underwent surgical resection is established for constructing new treatment strategy for R-PDAC.

Methods : From Jan 2006 to Dec 2017, 231 patients with R PDAC were included in this study. These patients were divided into 3 groups according to CA19-9 level and tumor size on contrast enhanced CT scan, which were prognostic factors using multi-variate analysis using pre-operative factors (High risk: CA19-9>150 and Tumor diameter>20mm, Low risk: CA19-9?150 and Tumor diameter?20mm, Intermediate risk: others).　Post-operative survival was compared between 3 groups and pre-operative poor prognostic factors were analyzed.

Results : In 231 patients, MST was 32.0 months. In each risk group (High(n=78)/Intermediate(n=105)/Low risk(n=48)), MST were 22.2/31.6/54.6 months (p<0.001). In multivariate analysis, High risk group was an only significant independent poor prognostic factor(HR:2.18,95%CI:1.50-3.14,p<0.001）. NAT was performed in 60 patients and there was no significant difference in survival between NAT group and upfront surgery group (p=0.442）. In patients with CA19-9 < 150 U/ml after NAT who underwent surgical resection, there was a better tendency in prognosis compared with the patients performed resection with CA19-9?150 U/ml (MST 35.9：15.1 M、p=0.083).

Conclusions : High risk group was the independent poor prognostic factor for R-PDAC. For these patients, the new therapeutic strategy that neoadjuvant therapy and surgical resection after a CA19-9 decrease less than 150U/ml will be needed.
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