Evaluating survival benefits for adding zoledronic acid to chemotherapy in stage II and III breast cancer patients

This study evaluated whether zoledronic acid (Zometa) can help reduce recurrence (return of the cancer) and improve survival for patients with stage II/III breast cancer (BC).  

Stage II and Stage III BC is cancer that has spread to the lymph nodes around the breast (under the armpit or above collarbone), but not to other organs or tissues in the body. This stage of BC is often treated with multiple therapies, such as surgery to remove the cancer, followed by cancer fighting drugs (chemotherapy), x-rays (radiation therapy), hormonal therapy or other additional therapies. Some BC grow in the presence of estrogen (a female hormone). These are called estrogen receptor-positive (ER+) BC and usually stop growing when treated with hormone-blocking therapy (hormonal therapy). Other types of BC do not need female hormones to grow. These are called estrogen receptor-negative (ER-) BC and they do not stop growing when treated with hormonal therapy. Zoledronic acid (Zol) is a drug used to treat hypercalcemia (high levels of calcium in the blood) that occurs in patients with cancer. Zol is also used for the treatment of osteoporosis (loss of bone mass which makes the bones fragile) and bone complications of cancer. Recent studies suggest that this drug may somehow help the body fight off small groups of cancer cells (micro-metastases) which break off from the cancer and float through the bloodstream to the bone marrow (the fatty and bloody tissue that fills most bone cavities). 

This study included 119 women, with newly diagnosed stage II or III BC. Patients were randomly assigned to receive either 4 mg Zol every three weeks for 1 year plus chemotherapy or chemotherapy alone. All patients were encouraged to take calcium and vitamin D daily. The main parameters evaluated were disease-free survival or DFS (defined as the percentage of living patients cured of the disease) and overall survival or OS (the percentage of patients who have survived for a certain period of time after treatment). After approximately 5 years of follow up, the addition of Zol to chemotherapy did not change DFS and OS for the whole group of patients. However, a subgroup of patients (patients with ER- BC) had a 64% improvement in DFS and a 62.5% improvement in OS with the addition of Zol to chemotherapy.

In summary, in this study, the addition of Zol to chemotherapy improved DFS and OS only in a subgroup of patients with ER- BC.

This was a small study, and did not have enough participants to fully evaluate subgroups. Future studies, with larger groups of patients are needed to confirm the findings of this research.

This study was funded by Novartis, the manufacturer of Zometa.

Ask your doctor whether adding zoledronic acid to your therapy may be helpful.