Possible Predictor Of Breast Cancer Survivability Identified

INDIANAPOLIS--Researchers at the Indiana University School of Medicine have studied 280 women and identified a factor which may indicate why some patients with metastatic breast cancer live longer than others. The results were presented Tuesday, May 20, at the annual meeting of the American Society of Clinical Oncology (ASCO) in Denver.

Michael Stender, M.D., an oncology fellow, and George Sledge, M.D., Ballve-Lantero Professor of Oncology at the Indiana University School of Medicine, studied the level of Her-2 in a group of patients enrolled in an Eastern Cooperative Oncology Group (ECOG) study of patients with metastatic breast cancer. Her-2 is a protein produced by a specific gene found in some breast cancer cells. Those patients who had a moderate to high level of Her-2 did significantly less well than patients with minimal or undetectable levels (Her-2 negative). Patients who were Her-2 negative lived an average of 30.2 months. Those with positive Her-2 levels survived 17.7 months.

Previous studies have shown that breast cancer patients who are estrogen receptor positive (hormone sensitive) often survive longer than those whose estrogen receptors are negative because they are more likely to respond to certain types of therapy.

The new Indiana University study found that women who were hormone sensitive and Her-2 negative had prolonged survival. Hormone sensitive patients with positive Her-2 levels did no better than estrogen receptor negative women.

Thus, Her-2 expression may explain why not all hormone sensitive patients do as well as expected. Patients whose breast cancer produces the Her-2 protein do not appear to benefit from being hormone sensitive.

"The results of this study suggest that a simple blood test may predict patients who may be candidates for biological therapy such as antibody treatments instead of chemotherapy," said Dr. Sledge. Studies up to this time have not described a particular chemotherapy which seems to overcome the negative effects of Her-2 expression.

No association was found between the presence of Her-2 in the blood and response to either Taxol or Adriamycin, two drugs commonly used to treat breast cancer. Further studies are needed to determine whether there is a link between Her-2 levels and other chemotherapy agents.

"It is exciting to think that a blood test to determine Her-2 level could be used to help physicians provide optimal treatment for breast cancer patients and possibly prolong life while minimizing toxicity," said Dr. Stender.

Dr. Stender has been awarded an ASCO achievement award for this study in recognition of outstanding research by a physician in fellowship training. In a plenary lecture at the same meeting, Dr. Sledge is presenting data on the national multi-center ECOG Taxol versus Adriamycin study. Other members of the research team are Donna Neuberg of the Dana Farber Cancer Institute and William Wood of Emory University.

The study was supported, in part, by an unrestricted grant from Bristol-Myers Squibb Oncology. Chiron Diagnostics of East Walpole, Mass., provided the assay used to measure the level of Her-2 in the patient's plasma.

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