For patients with early breast cancer, five years of zoledronate treatment after chemotherapy does not improve prognosis versus two years of treatment, according to a study published online June 24 in JAMA Oncology.
Thomas W. P. Friedl, Ph.D., from the University Hospital Ulm in Germany, and colleagues compared two years of zoledronate treatment to five years of zoledronate treatment following adjuvant chemotherapy for patients with node-positive or high-risk node-negative primary invasive breast cancer in a randomized open-label clinical trial. A total of 3,754 patients were enrolled and initially randomly assigned to adjuvant chemotherapy (three cycles of fluorouracil, epirubicin, and cyclophosphamide followed by three cycles of docetaxel with or without gemcitabine) and subsequently underwent a second randomization to five or two years of zoledronate treatment. Data from 2,987 patients were available for analysis.
The researchers observed no significant difference between the zoledronate treatment arms in terms of disease-free survival, overall survival, or distant disease-free survival. Adverse events occurred more often in the five- versus two-year zoledronate treatment arm (46.2 versus 27.2 percent), especially for the skeletal-related events of bone pain (8.3 versus 3.7 percent) and arthralgia (5.1 versus 3.1 percent).
“Based on our results, the recommended three to five years of adjuvant bisphosphonate treatment for patients with high-risk early breast cancer as published in current clinical guidelines could be reduced,” the authors write.
Several authors disclosed financial ties to biopharmaceutical companies, including AstraZeneca, Chugai, Lilly, Novartis, and Sanofi-Aventis, which together with Menarini Silicon Biosystems (formerly Veridex) provided funding for the study.