Research Notes
Assessing a new breast cancer therapy
Mathematical models indicate that women with estrogen-positive breast cancer that has not spread to their lymph nodes are less likely to have a recurrence of the disease in 10 years if they switch from tamoxifen to an aromatase inhibitor after two-and-a-half years (yellow line) than if they take tamoxifen alone (blue line), an aromatase inhibitor alone (green line), or switch from tamoxifen to an aromatase inhibitor after five years (red line).
The advent of a new class of drugs known as aromatase inhibitors for treating certain types of breast cancer has presented doctors with a new set of quandaries: Is an aromatase inhibitor more effective on its own than tamoxifen, the standard therapy, or should the two medications be given sequentially? If the latter, how long should one medication be given before switching to the other?
Although studies are under way to answer these questions, they can take years to complete. In the meantime, a group of Dana-Farber investigators has used high-level mathematics to help guide physicians and patients.
In research presented at the San Antonio Breast Cancer Symposium late last year, investigators led by Rinaa Punglia, MD, MPH, and Harold Burstein, MD, PhD, of the Women's Cancers Program combined data from published studies and used computer models to compare the effectiveness of tamoxifen alone, an aromatase inhibitor alone, and tamoxifen followed by an aromatase inhibitor.
The research suggests that for postmenopausal women whose breast cancer growth is stimulated by the hormone estrogen (so-called ER-positive cancers), two to three years of tamoxifen therapy followed by treatment with an aromatase inhibitor was better at preventing a cancer recurrence over a 10-year time period than was either drug alone or a longer period of tamoxifen therapy before switching to the other drug.
"Mathematical modeling enables us to make projections about ongoing research using data from previous studies," Dr. Punglia comments. "In this case, it can give physicians and patients confidence that their treatment decisions are based on the best information available, while definitive studies are still under way."
Working with Dr. Punglia and Dr. Burstein on the project were Eric Winer, MD, director of the Breast Oncology Center at Dana-Farber; Jane Weeks, MD, MSc, chief of the Division of Population Sciences at Dana-Farber; and Karen Kuntz, ScD, of the Harvard School of Public Health.
