In patients without bone metastasis, patients whose RB1 expression were low tended to have faster time to CRPC (mean 15 months, 95% CI: 8.9–12.1) than those who presented with high expression (mean 36.4, 95% CI: 29.2–43.7) (p = 0.017, Fig. 4A). Here, RB1 is linked to bone metastasis.