Validation of serum C-reactive protein (CRP) as an independent prognostic factor for disease-free survival in patients with localised renal cell carcinoma (RCC)

Objective To validate high-sensitivity C-reactive protein (hs-CRP) serum levels as an independent marker for disease-free survival (DFS) in clinically localised clear cell renal cell carcinoma (ccRCC). Patients and Methods In all, 403 consecutive patients with clinically localised (T1-3N0M0) ccRCC treated by radical or partial nephrectomy were enrolled. Preoperative serum levels of hs-CRP were evaluated as both a continuous and categorical variables. Associations with clinical (age, gender) and pathological variables (T classification, grade, tumour necrosis) were assessed with the chi-square and Kruskal-Wallis tests. Univariable and multivariable Cox proportional hazards models were fitted. The prognostic accuracy (PA) was assessed with Harrell's C-index. Results The mean hs-CRP level was 1.32mg/dL. The hs-CRP levels were associated with T classification (P = 0.05), high-grade disease (P < 0.001) and tumour necrosis (P = 0.003). After a median follow-up of 43 months, 41 patients (10.1%) had developed disease recurrence. With each unit increase in hs-CRP levels, the risk of recurrence increased by 10% (hazard ratio 1.10, P = 0.015). The thresholds of 0.5 and 0.75mg/dL showed the best discrimination for stratification of patients according to the probability of recurrence. These categorically coded hs-CRP levels were identified as independent prognostic factors in multivariable analyses (P < 0.001) and led to a significant increase in the PA of a multivariable base model containing the variables of the Stage, Size, Grade and Necrosis' (SSIGN) score. Conclusions This study validates preoperative serum hs-CRP levels as independent prognostic factor after surgery for localised ccRCC. Hs-CRP may be included in standard prognostic modelling after surgery and may guide surveillance and inclusion in adjuvant clinical trials.