ESMO 2018: Zoledronic Acid and Letrozole vs. Tamoxifen in Early Breast Cancer
Posted: Tuesday, November 20, 2018
A combination therapy of zoledronic acid and letrozole (ZL) resulted in better disease-free survival in premenopausal women with hormone receptor–positive early breast cancer, according to a study by Francesco Perrone MD, PhD, Director of the Clinical Trials Unit at the Instituto Nazionale Tumori in Naples, and colleagues. Dr. Perrone presented these findings from the HOBOE-2 trial at the 2018 European Society for Medical Oncology (ESMO) Congress in Munich (Abstract LBA14).
“Our hypothesis is that the drug modifies the bone microenvironment, [which] is the niche where breast cancer micrometastases remain in a state of dormancy, potentially for many years,” stated Dr. Perrone in an ESMO press release. “The two mechanisms are partially independent and, therefore, may sum up to give an additive benefit.”
The trial followed 1,065 patients with estrogen/progesterone receptor–positive breast cancer. Patients were randomly assigned to be given tamoxifen, letrozole, or ZL therapy and assessed after a median 65-month follow-up. A total of 32 events (breast cancer recurrence, second breast, nonbreast cancers, or deaths) occurred in patients treated with ZL, whereas 58 occurred with tamoxifen and 44 with letrozole alone. Disease-free survival was improved with ZL than with tamoxifen alone, with an absolute advantage of 8% in disease-free survival for all groups aside from those overexpressing HER2. It is important to note that side effects were more frequent in patients treated with ZL, so this treatment may be best suited for women with immediate-high risk, where the benefit outweighs the risk.
Dr. Perrone hypothesized that “if the size of the benefit [seen] is confirmed with longer follow-up, ZL treatment might turn out to be a highly cost-effective treatment for premenopausal hormone receptor–positive breast cancer,” given that both zoledronic acid and letrozole are relatively inexpensive agents.
