COL6A1 and nonpapillary renal cell carcinoma: In the TCGA cohort, high COL6A1 expression was an independent prognostic factor for DFS in 417 patients with localized ccRCC (HR: 3.106 95%CI 1.534–6.288, P < 0.01, Table 4) after adjustment for age, sex, T stage, N stage and AJCC stage.