Safety and Efficacy of Long-Term Zoledronic Acid in Advanced Breast Cancer with Bone Metastasis in South China

Table 4

Quantity of SREs in ABC with bone metastasis after treatment with ZA.

	Group A (ZA 6–24 months); n = 293	Group B (ZA > 24 months); n = 273	value
No events^a	190 (64.8%)	135 (49.4%)	0.017
Single event^b	58 (19.8%)	69 (25.3%)
Multiple events^c	45 (15.4%)	69 (25.3%)

SRE: skeletal-related event, MBC: metastatic breast cancer, and ZA: zoledronic acid. ^aNo event was defined as no SRE after the initiation of ZA. ^bSingle event indicated that the enrolled cases had one single SRE after the initiation of ZA. ^cMultiple events indicated that the enrolled cases had two or more SREs after treatment with ZA.