Oral bisphosphonate did not improve prognosis for patients with breast cancer

Volker Möbus, Ph.D., head of the department of obstetrics and gynecology at Klinikum Frankfurt Höchst GmbH in Frankfurt, presented the results from the German Adjuvant Intergroup Node Positive (GAIN) Study, at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium, held Dec. 6-10, 2011.

Möbus and his colleagues randomly assigned 3,023 patients with breast cancer to two different chemotherapy regimens and then further assigned them to 50 milligrams of oral ibandronate or observation. After a median follow-up of 38.7 months, "we found no significant difference between groups in the primary endpoint" of disease-free survival, Möbus said.

He described these results as "disappointing" compared with other studies. In the Adjuvant Treatment with Zoledronic Acid in Stage II/III Breast Cancer (AZURE) trial, for example, Möbus said that the subgroup of postmenopausal patients showed an improvement in recurrence-free and overall survival.

"So far, clinical trials of adjuvant bisphosphonates in early breast cancer have shown variable results, independent from their application (oral compared with intravenous)," Möbus said.

More recently, two trials — the Austrian Breast & Colorectal Study Group (ABCSG-12) and the Zometa-Femara Adjuvant Synergy Trial (ZO-FAST) — have shown significant benefit in patients with hormone receptor-positive breast cancer who were postmenopausal and received an endocrine treatment only.

Möbus said that in the AZURE trial, 95 percent of patients received chemotherapy and only postmenopausal patients showed an improvement in the zoledronic acid group. "In our [GAIN] trial, all patients received dose-dense chemotherapy, and unfortunately, we could not show a benefit in any subgroup," he said. "We speculate that the high efficacy of dose-dense chemotherapy erases the potential effect of bisphosphonates, which is shown in patients with endocrine treatment only."

Provided by American Association for Cancer Research