Usefulness of serum creatinine and cystatin C ratio as a screening tool for predicting prognosis in patients with pancreatic cancer

Abstract Aim This study aimed to evaluate the usefulness of the serum creatinine/cystatin C (Cr/CysC) ratio as a prognostic factor after pancreatic surgery in patients with pancreatic cancer. Methods We retrospectively analyzed the data of 88 patients with pancreatic ductal carcinoma who underwent pancreatic surgery from January 2017 to December 2020. CysC measured from frozen serum samples and circulating Cr levels were used to calculate the Cr/CysC ratio. The cutoff value of the Cr/CysC ratio was determined using receiver operating characteristic curves. Cox proportional hazards model analysis and survival curves were applied to identify the prognostic factors. Results The optimal cutoff value of the Cr/CysC ratio for predicting mortality after surgery was 1.05. This study included 20 (22.7%) and 68 (77.3%) patients with high and low Cr/CysC ratios, respectively. The low Cr/CysC ratio was significantly associated with female sex ( p = 0.020) and higher levels of C‐reactive protein ( p = 0.020). The postoperative length of stay was significantly longer in patients with low Cr/CysC rates ( p = 0.044). Patients with low Cr/CysC ratio showed poorer prognosis in relapse‐free survival (hazard ratio [HR] = 3.33; 95% confidence interval [CI]: 1.54–4.20; p = 0.002) and overall survival (HR = 2.52, 95% CI: 1.04–6.10, p = 0.041), respectively, which were significantly worse than in those with high Cr/CysC ratios ( p = 0.003 and 0.049, respectively). Conclusion The Cr/CysC ratio could be a useful screening tool for predicting the prognosis of patients with pancreatic ductal carcinoma undergoing pancreatic surgery.