C‐reactive protein is a strong predictor for anaemia in renal cell carcinoma: role of IL‐6 in overall survival

Study Type – Prognostic (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? The incidence of renal cell carcinoma (RCC)‐associated anaemia has been linked with more aggressive tumours. Metastatic RCC patients with elevated IL‐6 levels have significantly decreased haemoglobin concentrations. We elucidate the association of progression of advanced RCC with anaemia and different factors influencing tumour‐associated anaemia. Interleukin‐6 emerges as a possible target to treat cancer‐related anaemia in metastatic RCC. OBJECTIVE • To elucidate the association of progression of advanced renal cell carcinoma with anaemia and investigate factors influencing tumor‐associated anaemia. PATIENTS AND METHODS • We analyzed different clinical variables to study associations with anaemia in 86 metastatic renal cell carcinoma patients. • 45 (52%) of patients had already developed anaemia prior to therapy. RESULTS • Anaemic patients had an increase in the serum markers C‐reactive protein (CRP), IL‐6 and erythropoietin (EPO). In addition we observed substantial correlation between IL‐6 and CRP serum levels (R = 0.639, P < 0.0001). • Univariate logistic regression analysis revealed that patients with IL‐6 >10 pg/mL had a considerable increase in risk for anaemia (odds ratio 3.86, P = 0.003). • In addition, patients with CRP >0.7 mg/dL had a very strong increase in risk for anaemia (OR = 14.08, P < 0.0001). • Stepwise multivariate logistic regression analysis confirmed CRP >0.7 mg/mL as the only independent predictor for anaemia. Cox‐regression modeling selected serum IL‐6 as the strongest independent prognostic indicator (hazard ratio 3.58, P < 0.0001). CONCLUSION • Anaemia depends on serum IL‐6, which is a strong inductor of CRP and regulator of the iron‐transport. Serum IL‐6 may be considered as a target to treat cancer‐related anaemia.