Breast tumor's biological traits guide hormone therapy

May 15, 2005

ORLANDO, Fla.--The characteristics of an individual patient's breast cancer can help physicians choose the most effective treatment sequence with tamoxifen and the newer aromatase inhibitors, according to a study led by researchers from Dana-Farber Cancer Institute in Boston. The findings (abstract 529) will be presented in a poster session at the American Society of Clinical Oncology's annual meeting on Sunday, May 15, 1 p.m., Level 4, 414A.

Tamoxifen has been used for many years to reduce the risk of recurrence in women following breast cancer treatment. More recently, drugs called aromatase inhibitors that inhibit the production of estrogen in the body have been found highly effective and in some cases superior. But whether women should take tamoxifen alone, an aromatase inhibitor alone, or tamoxifen for two years followed by an aromatase inhibitor are issues yet to be clarified by clinical trials.

Because there are no data comparing different hormonal strategies for breast cancer treatment, Harold Burstein, MD, PhD, of Dana-Farber, Riina Punglia, MD, of Brigham and Women's Hospital, and their colleagues developed a mathematical model using emerging clinical trial data to simulate 10-year disease-free survival in postmenopausal women with hormone-receptor positive breast cancer.

"The simulations we ran suggest that the best treatment strategy is determined by the tumor's biology, and that not all patients should necessarily be given the same treatment," explains Burstein. "In so many areas of breast cancer medicine, we are learning that 'one size does not fit all.'"

The model revealed that the best treatment for an individual woman depended on whether her tumor was positive both for estrogen receptors (ER+) and progesterone receptors (PgR+). For women whose tumors were ER+ and PgR+, the best course appears to be tamoxifen for two years and then aromatase inhibitor treatment after two years. If the tumor is ER+ and PgR-, however, upfront treatment with an aromatase inhibitor may be superior, according to the model.

Burstein, who is also an assistant professor at Harvard Medical School, said that until data is available from prospective randomized trials, this model might serve as a useful guide to clinicians as they evaluate their patients' treatment plans.
In addition to Burstein and Punglia, the study's other authors are Eric Winer, MD, and Jane Weeks, MD, Dana-Farber, and Karen Kuntz, ScD, Harvard School of Public Health.

Dana-Farber Cancer Institute ( is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), designated a comprehensive cancer center by the National Cancer Institute.

Dana-Farber Cancer Institute

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