Further subgroup analysis, by Smith et al [24], demonstrated that shorter bone metastasis free survival was observed as PSA doubling time decreased below 8 months and that denosumab consistently increased bone metastasis free survival in participants with shorter PSA doubling times (median of 6, 7.2 and 7.5 months among men with PSA doubling times ≤10 (HR 0.84; p = 0.042), ≤6 (HR 0.77; p = 0.006), and ≤4 months respectively (HR 0.71; p = 0.004). Here, KLK3 is linked to bone metastasis.