Another supportive article regarding Zometa (zoledronic acid):
"All but the youngest patients with hormone-sensitive breast cancer had significant improvement in disease-free survival (DFS) when they received zoledronic acid (Zometa) in addition to endocrine therapy, results of two large trials showed.
The two trials -- known as ZO-FAST and ABCSG-12 -- both showed about a 30% reduction in the relative risk of progression in women treated with zoledronic acid, which also improved overall survival (a secondary endpoint) in the ZO-FAST trial. A comparison of immediate versus delayed initiation of the intravenous bisphosphonate demonstrated a significant advantage for starting the drug at the same time as endocrine therapy.
Subgroup analyses showed that only patients younger than 40 did not have improved DFS when treated with zoledronic acid, as reported here at the San Antonio Breast Cancer Symposium.
"Bone-targeted treatments may modify the bone microenvironment and may affect cancer stem cells," Michael Gnant, MD, of the Medical University of Vienna in Austria, said.
Long-term results from the ZO-FAST trial showed a 34% improvement in DFS (a secondary endpoint) in postmenopausal breast cancer patients who received zoledronic acid at the same time as the aromatase inhibitor letrozole, compared with women whose treatment with the bone-targeted drug did not start until occurrence of a prespecified clinical event.
ABCSG-12 trial involved 1,800 women with early-stage premenopausal breast cancer patients treated with endocrine therapy but no chemotherapy. Following surgery, all patients received goserelin and were randomized to tamoxifen or anastrozole with or without zoledronic acid, continued for three years.
The primary endpoint was DFS.
The patients had a median age of 45, and 22% of the study population was 40 or younger. Additionally, 78% of the patients had T1 disease, 67% had no nodal involvement, 80% had histologic grade 1 or 2, and fewer than 4% were estrogen-receptor (ER) negative.
Subgroup analysis showed a consistent trend in favor of treatment with the bisphosphonate, as results were similar regardless of nodal status, endocrine agent, ER expression level, grade, or stage.
ABCSG-12 also demonstrated the effectiveness of first-line endocrine therapy for early breast cancer without the use of chemotherapy, he added, as the study population had a seven-year overall survival exceeding 95%.
Zoledronic acid given concurrently with endocrine therapy was associated with a 34% improvement in DFS compared with delayed initiation of the bisphosphonate, according to an exploratory analysis of the ZO-FAST study, said Richard de Boer, MD, of the Royal Melbourne Hospital in Australia.
All patients received the aromatase inhibitor letrozole (Femara) and were randomized to start zoledronic acid immediately or to delay therapy until a decline in bone density T-score to less than -2, clinical fracture, or asymptomatic fracture at 36 months."