Development and Validation of a Nomogram of Predict Eligibility for Second-line Chemotherapy in Pancreatic Cancer

Background/Aim: For pancreatic cancer, combination therapies, such as gemcitabine plus nab-paclitaxel (GnP) or FOLFIRINOX (FFX), are recommended as first-line (FL) chemotherapy. Second-line (SL) chemotherapy has been shown to improve survival, but factors predicting eligibility for SL chemotherapy remain unclear. This study aimed to identify factors predicting eligibility for SL chemotherapy and to develop a predictive nomogram. Patients and Methods: This retrospective multicenter study included 278 patients with unresectable PC who received FL chemotherapy between 2017 and 2023. Patients were divided into the development (n=140) and external validation (n=138) cohorts. Univariate and multivariate logistic regression analyses were performed to identify predictors of eligibility for SL chemotherapy. A nomogram was developed using these independent predictors and was validated via calibration curves and c-statistics. Results: The independent predictors of eligibility for SL chemotherapy included age (<70 years old), C-reactive protein (CRP) levels, and the FL regimen (combination vs. monotherapy). The nomogram demonstrated good predictive accuracy (c-statistic: 0.78) in the development cohort and acceptable accuracy (c-statistic: 0.68) in the validation cohort. The calibration curves showed good agreement between predicted and observed probabilities. Conclusion: The nomogram developed herein is a reliable tool for predicting eligibility for SL chemotherapy among PC patients, thereby facilitating informed treatment decisions.