Development of a CT-based scoring system to predict progression after intraoperative radiotherapy in locally advanced pancreatic cancer with initial stable disease

Abstract Objectives We aimed to develop a risk scoring system integrating CT imaging features and serum carbohydrate antigen 19 − 9 (CA19-9) for stratifying the short-term outcomes in locally advanced pancreatic cancer (LAPC) patients receiving intraoperative radiotherapy (IORT) with initial stable disease (SD). Materials and Methods We retrospectively recruited 103 consecutive patients with LAPC who received IORT as first-line treatment. All patients underwent CT examinations and serum CA19-9 test baseline and post-IORT. Clinical and CT imaging features were analyzed. The risk scoring system was constructed using the coefficient of the independent risk factors for progression-free survival (PFS) from cox regression model. Time-dependent receiver operating characteristic (ROC) curve was used to evaluate the predictive performance of the scoring system. Results All patients developed disease progression after IORT and the median PFS time was 6.40 (95% confidence interval [CI]:4.95–7.86) months. Multivariable analysis revealed that CA19-9 non-response (hazard ratio [HR] = 1.672, P = 0.018), the percentage change of relative enhanced ratio (HR = 2.318, P = 0.030), rim-enhancement (HR = 1.784, P = 0.007), and peripancreatic fat infiltration (HR, 1.799, P = 0.006) were significant correlated with poor PFS. Time-dependent ROC showed a satisfactory predictive performance for disease progress with area under the curve (AUC) all above 0.70. Low-risk patients (risk score < 5) progress significantly slower than high-risk patients (risk score ≥ 5) ( P < 0.001). Conclusion The scoring system integrating CT imaging features and CA19-9 can be used as a convenient and practical method for prognosis prediction in LAPC patients showing SD receiving IORT.