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Researchers at Memorial Sloan-Kettering and other cancer centers recently
reported on several new methods to treat patients whose breast cancer has spread
(metastasized) to other parts of the body.
At the 35th annual meeting of the American Society of Clinical Oncology (ASCO) in May, MSKCC investigators presented data demonstrating that the addition of a monoclonal antibody called "trastuzumab" (marketed as Herceptin®) to two standard chemotherapy regimens substantially increased survival among patients with metastatic breast cancer. Today, there are approximately 164,000 women in the United States with metastatic breast cancer, 25 to 30 percent of whom have tumors that produce too much of the HER2 protein. HER2 increases a cancer’s growth rate and ability to metastasize; the trastuzumab antibody targets and inactivates this protein.
In one study, half of the patients received chemotherapy alone, the other half chemotherapy with trastuzumab. However, all patients were given the opportunity to receive trastuzumab if their cancers grew during or after such treatment. At an average follow-up of 29 months, patients who received simultaneous chemotherapy plus the antibody had a median survival rate of 25.4 months, compared to 20.3 months for those who received chemotherapy alone--an improvement of 25 percent.
"Few clinical trials for advanced breast cancer have demonstrated a survival advantage of one treatment over another," said Dr. Larry Norton, Head of MSK’s Division of Solid Tumor Oncology, who presented these data at ASCO. "What is remarkable about this result is that
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| Dr. Larry Norton is leading MSK's participation in studies of new treatments that appear to improve survival for patients with advanced breast cancer. |
Also in the headlines for breast-cancer patients are new studies indicating that bone marrow transplants may not be more effective than conventional treatment. Since the early 1990s, bone marrow transplantation--a very toxic and sometimes life-threatening procedure--has been regarded by some physicians as the best treatment for aggressive or advanced breast cancer, even though data regarding the technique’s effectiveness have not appeared until now.
In this type of bone marrow transplant, doctors withdraw and then freeze blood-forming cells from the patient’s bone marrow or blood. They then give high doses of chemotherapy drugs in an attempt to kill the cancer cells — drugs that also suppress the body’s white blood cells in the process. Doctors then "rescue" the patient by reinfusing the blood-forming cells to restore the immune system. The transplant allows physicians to use vastly higher doses of chemotherapy than standard regimens.
"Back in the late 1970s, Dr. Richard Simon and I came up with the Norton-Simon Hypothesis, which basically suggested that a burst of high-dose chemotherapy might be totally curative, or it might not help at all," said Dr. Norton. "Since bone marrow transplantation was already being established for leukemias and lymphomas, we thought this would be an important question to study for breast cancer." The new data that now answer that question do not show a survival benefit for bone marrow transplantation in the treatment of women with advanced breast cancer.
A clinical trial testing this procedure in patients with many involved lymph nodes at the time of diagnosis, but no evidence of metastatic disease, is still being analyzed. But preliminary data--also presented at ASCO--show no survival difference yet between patients who received a transplant and those who got lower doses of the same chemotherapy. This trial is coordinated by the Breast Cancer Committee of the Cancer and Leukemia Group B, chaired by Dr. Norton.
Although MSK has participated in national testing of bone marrow transplants for this disease, the institution has never routinely performed the technique. "I believe that patients with breast cancer should have bone marrow transplantation performed only in the context of randomized clinical trials," said Dr. Norton.
More important, perhaps, the international standard for chemotherapy has changed dramatically over the last several years. "Conventional chemotherapy means something different now from when these transplant trials started," said Dr. Norton. "Based on work done here at MSK, the world standard for chemotherapy for high-risk breast cancer now includes the drugs anthracycline and cyclophosphamide followed by paclitaxel. A regimen based on this work, less toxic and more easily administered than transplantation, is currently being tested versus transplantation in a major international study." MSK continues to develop and refine better tolerated treatments based on a superior knowledge of the biology of cancer. These studies are being supported by the National Cancer Institute.
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