Breast-Cancer Adjuvant Therapy with Zoledronic Acid

29 October, 2011 (18:19) | Cancer | By: Health news

Metastasis is a complex process that is dependent on both the biologic features of the primary tumor and cellular interactions within host tissues. In the bone microenvironment, cancer cells stimulate osteoblasts to release receptor activator of nuclear factor κB ligand (RANKL), which binds to its receptor, RANK, on both precursor and mature osteoclasts. The resulting increase in osteoclastic bone resorption leads to the release of bone-derived growth factors that may provide a fertile environment for survival and growth of adjacent cancer cells. Thus, targeting bone-cell function provides a potential additional approach to preventing bone metastases as a component of standard adjuvant therapy. In many in vivo models, bisphosphonates prevent or delay metastasis. In addition, synergistic interactions between aminobisphosphonates and cytotoxic drugs have been shown in preclinical models.

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In patients with early-stage breast cancer, several clinical trials have suggested that the adjuvant use of bisphosphonates reduces rates of recurrence and death.6-8 In addition, despite a lack of regulatory approval in most health care systems, the inclusion of a bisphosphonate as part of adjuvant therapy has become increasingly widespread. In this randomized, controlled, open-label phase 3 study, called the Adjuvant Zoledronic Acid to Reduce Recurrence (AZURE) trial, we evaluated the adjuvant use of zoledronic acid in a broad population of patients with stage II or III early-stage breast cancer.


Study Patients

The research protocol and statistical analysis plan are available with the full text of this article at To be eligible for the study, all the patients had to be at least 18 years of age, have a Karnofsky performance status of at least 80, and have a histologically confirmed breast cancer with axillary lymph-node metastasis (N1) or a T3–T4 primary tumor. Complete primary tumor resection was mandated or intended after neoadjuvant therapy. In addition, patients who were eligible for completion surgery (margin excision, mastectomy, or axillary lymph-node dissection) after completion of adjuvant chemotherapy could be included.

Patients were not eligible if there was clinical or imaging evidence of distant metastases or if complete treatment of the primary breast tumor and regional lymph nodes was not possible. Other exclusion criteria included a cancer diagnosis within the preceding 5 years, use of bisphosphonates during the previous year, or a diagnosis of osteoporosis or other bone disease likely to require bone-targeted treatment. The serum creatinine level had to be less than 1.5 times the upper limit of the normal range. In 2005, after case reports of osteonecrosis of the jaw associated with bisphosphonates,9 an amendment was adopted to exclude patients with clinically significant, active dental problems or planned jaw surgery.

Randomization and Treatment

After providing written informed consent, patients were randomly assigned in a 1:1 ratio to receive standard adjuvant systemic therapy (control group) or standard adjuvant systemic therapy along with zoledronic acid. The zoledronic acid was administered immediately after each cycle of adjuvant chemotherapy in a 4-mg dose by intravenous infusion every 3 to 4 weeks for 6 cycles and then every 3 months for 8 doses, followed by 5 cycles on a 6-month schedule for a total of 5 years. Dose adjustments for renal-function abnormalities were recommended in accordance with the product license. Daily oral supplements containing calcium (400 to 1000 mg) and vitamin D (200 to 500 IU) were recommended for all patients during the first 6 months and were continued thereafter at the discretion of the treating physician.

External-beam radiotherapy to the breast and chest wall, with or without irradiation of regional lymph nodes, and adjuvant cytotoxic and endocrine treatments were given in accordance with standard protocols at each participating institution. After regulatory approval of trastuzumab for adjuvant use, the drug was allowed in patients with HER2-positive tumors.