Systematic review and meta-analysis comparing zoledronic acid administered at 12-week and 4-week intervals in patients with bone metastasis.

Zoledronic acid is used to treat patients with bone metastasis, but the optimal dosing interval remains controversial. We therefore performed a systematic review and meta-analysis to compare the efficacy and safety of a 12-week interval of zoledronic acid with the standard 4-week interval. Three randomized controlled trials comprising 2650 patients were analyzed. Using a random-effects model, pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated. No differences in the occurrence of skeletal-related events (SREs: RR = 0.98; 95% CI = 0.86-1.12; P = 0.80) or grade 3/4 adverse events (RR = 0.91; 95% CI = 0.69-1.20; P = 0.52) were observed between the 12-week and 4-week groups. The 12-week group tended to have lower incidences of osteonecrosis of the jaw [13 (0.98%) vs. 23 (1.73%)] and kidney dysfunction [21 (1.68%) vs. 31 (2.45%)] than the 4-week group, though the difference did not reach statistical significance (RR = 0.58, 95% CI: 0.30-1.12; P = 0.11); (RR = 0.67, 95% CI: 0.39-1.15, P = 0.15). These data show that zoledronic acid administered at 12-week intervals instead of 4-week intervals does not increase the risk of SREs, and may reduce the incidence of osteonecrosis of the jaw and kidney dysfunction. This suggests the 12-week interval with zoledronic acid may be an acceptable treatment option.