The scientists reported that not only did zoledronic acid reduce death risk by 36%, but also that the risk of breast cancer recurrence dropped 28%. Patients were administered zoledronic acid along with adjuvant endocrine treatment, including ovarian function suppression.
The researchers presented data after 48, 62 and 84 months of follow-up. At 7 years there were "drastically" fewer breast cancer recurrences and better survival rates - and no reports of toxic side effects.
Professor of Surgery, at the University of Vienna's Medical School, Michael Gnant, M.D.,said:
"We have confirmed what this trial showed initially, which was both exciting and surprising. The continued success of this treatment means we can intervene early and still observe persistence of the benefit of treatment."
Dr. Gnant is also President of the ABCSG (Austrian Breast- and Colorectal Cancer Study Group).
The trial involved 1,803 women, all of them premenopausal with early-stage ER (estrogen receptor)-positive breast cancer. They were randomly selected to one of the four arms of the study. They were administered the following drugs or combinations for 36 months:
- Zoledronic acid plus anastrazole
- Zoledronic acid plus tamoxifen
According to the latest data at 84 months post-treatment, the patients on zoledronic acid had a 36% lower risk of death and a 29% smaller chance of the cancer coming back (recurrence). There were no reports of any patient developing renal failure or osteonecrosis (bone death) of the jaw. Gnant explained that this means the treatment is not only effective after seven years, but also safe.
The participants aged over 40 with presumed complete ovarian blockade were 34% less likely to experience cancer recurrence, and also had a 44% lower risk of death. For patients under 40 there appeared to be no significant survival benefits.
The team concluded that zoledronic acid, added to adjuvant endocrine therapy (including ovarian function suppression), should be a considered treatment option for females with ER-positive early breast cancer who have not yet reached the menopause.
Zoledronic acidZoledronic acid, also known as zoledronate, molecular formula C5H10N2O7P2, is a bisphosphonate, which is made and marketed by the Swiss company Novartis under the brand names Aclasta, Reclast, Zomera and Zometa. Zometa is prescribed to prevent bone fractures in patients with several types of cancers. Zoledronic acid is also used for osteoporosis treatment, and hypercalcemia of malignancy.
Written by Christian Nordqvist