Association between preoperative serum Cystatin‐C levels and postsurgical oncological prognosis in patients with PRCC: A retrospective cohort study

OBJECTIVE: Cystatin‐C (Cys‐C) is a predictor of several malignancies. However, whether Cys‐C levels predict prognosis in patients with papillary renal cell carcinoma (PRCC) remains uncertain. The aim of this study was to assess the correlation between Cys‐C and clinical outcomes in patients with PRCC. METHODS: The medical records of 137 patients with PRCC who underwent surgery at our institution from January 2008 to December 2020 were retrospectively analyzed. Data were divided into two subgroups based on cutoff values and the relationship between the Cys‐C group and their clinical outcomes was assessed. RESULTS: By the last follow‐up, 62 patients had died of various causes, 53 of whom died from PRCC. Sixty patients suffered recurrence or metastasis during follow‐up. Based on the cutoff value, the patients were divided into two groups: low Cys‐C group (Cys‐C < 1.25 mg/L, n = 92) and high Cys‐C group (Cys‐C ≥ 1.25 mg/L, n = 45). Pathological classification and serum Cys‐C levels were shown to be independent prognostic factors affecting clinical outcomes, according to multivariate Cox regression analysis (p < 0.05). After adjusting the Cox proportional hazards model, the risk of death was elevated in the high Cys‐C group. The results of the area under the curve for time‐dependent receiver operating characteristics analysis indicated that Cys‐C is a stable and reliable prognostic biomarker for predicting survival in patients with PRCC. Forest plots, constructed to better reflect the comparison of hazard ratios between the two groups, confirmed that Cys‐C levels were significantly associated with worsening overall survival. CONCLUSION: This study is the first to examine the relationship between preoperative serum Cys‐C levels and prognostic overall survival in patients with PRCC. Cys‐C may be a useful biomarker for preoperative screening of high‐risk patients who may require adjuvant therapy.