Multicenter phase 3 study of 5 versus 2 years of adjuvant zoledronate for early-stage breast cancer

The phase 3 randomized SUCCESS A clinical trial, at 250 centers in Germany, randomized patients with node-positive or high-risk node negative early breast cancer after chemotherapy to 5 versus 2 years of adjuvant zoledronate treatment. Disease-free survival (HR 0.97; p=0.81), overall survival (HR 0.98; p=0.90), and distant disease-free survival (HR 0.87; p=0.38) did not differ significantly between the two treatment arms. Adverse events were observed more frequently in the 5-year arm (46.2% of patients) than in the 2-year arm (27.2%). The authors conclude that the currently recommended bisphosphonate treatment duration of 3 to 5 years could be reduced.