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.