Zoledronic acid boosts antitumor effects of chemotherapy.(GYNECOLOGY)

SAN ANTONIO -- The addition of the bisphosphonate zoledronic acid to standard neoadjuvant chemotherapy reduces tumor size and results in more patients with a pathologic complete response than does chemotherapy alone, which suggests that the drug has direct antitumor activity, study results showed.

In a retrospective exploratory analysis involving more than 200 women, the adjusted mean residual invasive tumor sizes (RITS) in chemotherapy-alone and chemotherapy plus zoledronic acid groups were 42.4 mm and 28.2 mm, respectively--a significant difference (p = .002), Dr. Robert Coleman reported at the annual San Antonio Breast Cancer Symposium.

The pathologic complete response (pCR) rate (both breast and axilla) was 5.8% in the chemotherapy-alone arm and 10.9% in the combination arm (p = .033). In a multivariate analysis, the difference in pCR significantly favored the combination arm with an odds ratio of 3.7 (P = .03).

"It is the first patient-related evidence that this class of drugs may have direct antitumor activity" he said at a press conference during the meeting. "What these data suggest is that perhaps zoledronic acid is doing something more than just affecting bone." Dr. Coleman, an oncologist at the cancer research centre at Weston Park Hospital in Sheffield, England, presented the findings in a poster at the meeting.

"This is not a practice-changing study,'' he cautioned. "It's a hypothesis-generating study, which will lead to the design of specific neoadjuvant trials to look at this in more detail."

In the Neo-Adjuvant Zoledronic Acid to Reduce Recurrence (AZURE) trial, 3,360 women with stage II/III breast cancer were recruited to determine whether treatment with zoledronic acid in addition to neoadjuvant therapy improves disease-related outcomes. Women had to have a tumor size greater than 5 cm (T3) or features of locally advanced disease (T4) or biopsy-proven lymph node involvement. (N1).

They also had to be scheduled for definitive surgery and/or radical radiotherapy with curative intent within 6 months of starting neoadjuvant therapy. In addition, the time between the start of neoadjuvant treatment and the start of zoledronic acid had to be no greater than 30 days.