LAUSR

We thank Sun et al. for their comments and suggestions on the presented study. In the research field on inflammation prognostic scores in pancreatic ductal adenocarcinoma (PDAC), studies on several combinations of factors in different contexts of the disease have demonstrated significance in survival prognostication to some extent; however, among this multitude of studies, only a few of these scores were consistent and easily reproducable. In the presented study, we evaluated the impact of the Prognostic Index (PI) in a large cohort of 357 patients with PDAC and found that this index, consisting of C-reactive protein (CRP) and white blood count (WBC), is a solid independent tool for prognosis estimation. Using an additional, independent validation set might have proven its applicability to the fullest; however, from a statistical point of view, exploration of the utility of the PI, that has already been described to predict survival in non small-cell lung cancer, does not require further validation. We agree with the comment by Sun et al. that the balance between inflammation and host immunity plays an immanent role in PDAC development and dissemination; however, our aim for the present study was to test whether the PI is an independent prognostic tool for survival estimation in a representative sample of patients with PDAC undergoing resection. Moreover, the PI has the advantage of being easily available and applicable in daily routine, even in outpatient clinics. In contrast, accurate testing of immune function would require a more complex analysis, e.g. by T-cell proliferation assay or whole blood culture assay. We believe that comprehensive assessment of the patient’s individual inflammation and immune state at different stages of the disease is of particular importance in order to choose the appropriate treatment; however, to date, in-depth analysis of the inflammation and immune cascade has not been demonstrated to outperform a straightforward tool such as the PI. Sun et al. emphasized the frequency of bile stents before surgery in patients with PDAC and its influence on the prognostic strength of PI. With due regard to well-established prognostic factors, we explicitly analyzed the prognostic strength of the PI and found that it was influenced, but not diminished, by the history of obstructive jaundice followed by bile duct stent placement. However, future dedicated studies need to address the role of biliary duct occlusion, cholangitis and stent placement in inflammation and immune response with regard to the further course of the disease. In the presented study, the results and conclusions are based on multivariable analysis rather than Kaplan–Meier estimation and log-rank test statistics. Application of the two-stage test, as suggested, resulted in the same significance (p = 0.044). Taken together, we explored the utility of the PI for patients with PDAC undergoing resection. The advantage of this tool is that it provides an easily available and robust estimation of survival prognosis in daily clincial routine, since the CRP and WBC levels are most usually available in settings like in the outpatient clinic or at initial Society of Surgical Oncology 2020