Zoledronic acid with neoadjuvant chemotherapy may boost pathological response in breast cancer patients


Zoledronic acid with neoadjuvant chemotherapy may boost pathological response in breast cancer patients

SAN ANTONIO - New data suggest that adjuvant treatment with the bisphosphonate zoledronic acid (Zometa) plus chemotherapy may have a direct anti-tumor effect in women with breast cancer who are at high risk of a relapse.

The findings were reported here at the 2008 San Antonio Breast Cancer Symposium (SABCS).

Overall, the addition of zoledronic acid to chemotherapy before surgery produced an additional 33 percent decrease in tumor size, thereby reducing the need for mastectomy.

In addition, the data showed for the first time that zoledronic acid can help shrink primary tumors.

Robert Coleman, MD, with the University of Sheffield (UK), and colleagues elsewhere set out to determine whether the addition of zoledronic acid to chemotherapy influences pathological response to the primary tumor.

For the trial, the investigators used a subgroup of women who were enrolled in the Adjuvant Zoledronic Acid to Reduce Recurrence (AZURE) study, which explored whether treatment with zoledronic acid on top of adjuvant or neoadjuvant chemotherapy would improve disease outcomes in 3,360 women with stage II/III primary breast cancer.

Eligible patients received neoadjuvant chemotherapy according to local practice and were randomized to receive zoledronic acid 4 mg IV three to four times each week for six months in the neoadjuvant period in addition to chemotherapy or no additional treatment.

The primary surrogate endpoint for response was pathologically assessed residual invasive tumor size (RITS, mm) at surgery.

In the trial, 104 patients in the neoadjuvant subset received chemotherapy, and 101 patients received chemotherapy plus zoledronic acid.

Results showed a median RITS of 30 mm in the chemotherapy group and 20.5 in the chemotherapy plus zoledronic acid group. After controlling for variables like estrogen receptor status and treatment duration, results were 42.2 mm in the chemotherapy and 28.2 in the combination group, which amounts to a significant 33% reduction.

The pathological complete response rate was 5.8 percent in the chemotherapy arm versus 10.9 percent in the zoledronic acid group.

Importantly, the need for mastectomy was reduced by 16 percent in the zoledronic acid group.

"Overall, the data add to the evidence of a possible anti-tumor effect for zoledronic acid," Dr. Matthew Winter, MB, a co-author and clinical research fellow at the University of Sheffield, said.

Earlier this year, researchers reported phase III Austrian Breast & Colorectal Cancer Study that zoledronic acid added to endocrine therapy improves survival in premenopausal breast cancer patients.

According to the American Cancer Society, more than 1.3 million women worldwide were newly diagnosed with breast cancer in 2007.

jillstein03(at)gmail.com

Jill Stein is a Paris-based freelance medical writer.

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Section Issues On Medicine: Women health