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

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. The present study aimed to explore the pretherapeutic predictors for the attainability of CS in patients with UR-PDAC. The present study retrospectively evaluated 130 patients with UR-PDAC treated at Gifu University Hospital (Gifu, Japan) from January 2015 to December 2021. Survival analysis was performed using the Simon and Makuch-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 univariate analysis and age-adjusted Fine-Gray sub-distribution hazard model. The bootstrap bias-corrected area under the receiver operating characteristic curve analysis for predicting 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. Among the 130 patients included in the analysis, only 14 (11%) underwent CS. The median survival time was significantly longer in patients who underwent CS compared with patients without CS (56.3 vs. 14.1 months; P<0.001). The 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 significantly associated with CS. Moreover, TP >= 6.8, NLR <2.84 and LMR >= 3.87 were associated with a higher cumulative incidence of CS. In conclusion, pretherapeutic TP, NLR and LMR are clinically feasible biomarkers for predicting the attainability of CS in patients with UR-PDAC.