Expanding Our Knowledge of Chemotherapy

Chemotherapy has been the cornerstone of breast cancer treatment after surgery or radiation for many years, but ways to improve outcomes with chemotherapy are still being studied. Two drugs, Taxotere and Taxol, have been established as highly active in the treatment of metastatic breast cancer and are now being used in early breast cancer.

One study presented at the breast cancer symposium showed that Taxotere and Taxol result in comparable disease-free survival in women with node-positive or high-risk node-negative breast cancer. However, the side effect of neutropenia (decreased white blood cells), which increases the risk of infections, was greater with Taxotere than with Taxol. The study also found that weekly therapy with these agents (or "dose-dense" chemotherapy) produced similar disease-free survival compared with an every-three-week schedule, but for a subset of patients on Taxotere, the once-weekly dosing caused more side effects.

Another study showed that shorter intervals between chemotherapy doses (two weeks as opposed to three weeks), or a dose-dense approach, improved survival in women whose breast cancer had spread to the lymph nodes.

Advances in Treating Advanced Breast Cancer

Advances have also been made in the treatment of metastatic breast cancer. Kathy Miller, MD, with the Indiana University School of Medicine, reported the updated results of a large study called E2100, evaluating a targeted agent called Avastin. This new therapy reduces levels of a substance that promotes the growth of new blood vessels. In this way, Avastin prevents blood vessel growth and cuts off the nourishment required by tumors, causing them to shrink.

The E2100 study is an ongoing clinical trial of approximately 700 patients with previously untreated metastatic breast cancer. The study found that Taxol plus Avastin was superior to Taxol alone. Of the women treated with Avastin plus Taxol, about 28% responded to treatment compared with only about 14% treated with Taxol alone. Furthermore, Avastin extended disease-free survival by about five months compared with Taxol alone.

An important consideration regarding Avastin is determining how to combine this agent with other treatments for breast cancer. One study evaluated the combination of Avastin and Femara, a hormonal therapy, in patients with metastatic breast cancer. Researchers reported that Avastin in combination with Femara was well tolerated, with the most common side effects being high blood sugar, high blood pressure, fatigue, and joint pain.

Another study evaluated Avastin in combination with repetitive low-dose methotrexate and Cytoxan chemotherapy compared with the chemotherapy regimen alone. The study of 55 patients found that a partial response was observed for 29% of patients who received chemotherapy plus Avastin compared with only 10% of patients who received chemotherapy alone. In addition, the Avastin and chemotherapy combination was well tolerated. Further studies are needed to confirm these findings and to evaluate other ways to combine Avastin with current breast cancer treatments.