Pretherapeutic factors predicting conversion surgery in unresectable pancreatic ductal adenocarcinoma: a retrospective study

Abstract

Abstract Background Recently, conversion surgery (CS) has been reported to improve the prognosis in patients with unresectable pancreatic ductal adenocarcinoma (UR-PDAC) with a favorable response to intense chemotherapy or chemoradiotherapy. However, few pretherapeutic parameters predict the attainability of CS in patients with UR-PDAC. This study aimed to explore the pretherapeutic predictors for the attainability of CS in patients with UR-PDAC. Methods We retrospectively evaluated 130 patients with UR-PDAC treated at our institute from January 2015 to December 2021. The CS was performed only in patients with UR-PDAC who could expect R0 resection in the multidisciplinary meeting. The primary outcome of the study was CS. Survival analysis was performed using the Simon and Makuch’s modified Kaplan–Meier method. The hazard ratio (HR) was estimated using a time-varying Cox regression model. The association between each predictor and CS was evaluated using the univariable and age-adjusted Fine-Gray sub-distribution hazard model. The bootstrap bias-corrected area under the receiver operating characteristic curve analysis for predicting the CS was used to assess the cut-off values for each predictor. The cumulative incidence rate was calculated with CS as the outcome when divided into two groups based on the cut-off value of each pretherapeutic predictor. Results Among the 130 patients included in the analysis, only 14 (10.8%) patients underwent CS. The median survival time was significantly longer in patients who underwent CS compared with patients without CS (56.3 versus 14.1 months; p < 0.001). The univariable and age-adjusted Fine-Gray sub-distribution hazard regression showed that the total protein (TP) (HR 2.81, 95% confidence interval [CI] 1.19–6.65; p = 0.018), neutrophil-to-lymphocyte ratio (NLR) (HR 0.53, 95% CI 0.31–0.90; p = 0.020), and lymphocyte-to-monocyte ratio (LMR) (HR 1.28, 95% CI 1.07–1.53; p = 0.006) were statistically significantly associated with CS. Moreover, TP ≥ 6.8, NLR < 2.84, and LMR ≥ 3.87 were associated with a higher cumulative incidence of CS. Conclusions Pretherapeutic TP, NLR, and LMR are clinically feasible biomarkers for predicting the attainability of CS in patients with UR-PDAC.