SAN ANTONIO — Sharon Wilks, MD, FACP, medical oncologist with Texas Oncology within the US Oncology Network, spoke with HemOnc Today about a study presented at San Antonio Breast Cancer Symposium that showed extended adjuvant endocrine therapy with letrozole conferred no significant survival benefit to postmenopausal women with hormone receptor–positive breast cancer who completed 5 years of hormonal therapy.
Terry Mamounas, MD, MPH, medical director of the Comprehensive Breast Program at UF Health Cancer Center at Orlando Health, and colleagues sought to assess whether 5 years of letrozole extended DFS compared with placebo among patients who completed 5 years of hormonal therapy with either an aromatase inhibitor or tamoxifen followed by an aromatase inhibitor.
At 7 years, results showed no significant difference in DFS (87.4% vs. 81.3%; HR = 0.85) or OS (91.8% vs. 92.3%; HR = 1.15; 95% CI, 0.99-1.44) between patients assigned letrozole or placebo.
Cumulative incidence of osteoporotic fractures and arterial thrombotic events was higher with letrozole.
“There is an extension of side effects, including bone defects, fracture risk, arthralgia, hot flashes and menopausal-like symptoms,” Wilks told HemOnc Today. “Having women have that type of experience long term, countered by not showing a true benefit in OS, raises the question of whether we should adopt this practice in clinic.”
However, there remains the possibility that extended therapy could be beneficial for certain patient subgroups, Wilks said.
“Like with many other studies, there are a lot of questions about whether — from a molecular standpoint or through genomic-profiling tests — we might identify a cohort of patients more consistently and reliably that might benefit from extension of therapy,” she said. – by Mark Leiser
Mamounas P, et al. Abstract S1-05. Presented at: San Antonio Breast Cancer Symposium; Dec. 6-10, 2016; San Antonio, Texas.
Disclosure: Wilks reports no relevant financial disclosures.