IGF1 and renal cell carcinoma: As shown in Table 4 and Fig. 1, clinical stage, tumor grade, and IGF1 rs5742714 (GC/CC vs. GG) were associated with RCC survival in univariate analysis; a multivariate analysis found that clinical stage was the best prognostic factor for RCC survival, followed by tumor grade (P < 0.001, HR = 20.28; 95% CI = 8.78–46.87 and P = 0.002, HR = 4.24; 95% CI = 1.70–10.6, respectively).