Afterwards, to obtain a precise survival analysis, it has been possible to classify RCC patients in two different groups, according to the MDR-1 expression grade (Figure 1): in this way, we have found that patients with moderate-strong MDR-1 expression (score 2 – 3) had poorer survival rates, therefore a worse outcome, than the group of patients with weak or absent immunostaining (score 1). This evidence concerns the gene ABCB1 and renal cell carcinoma.