New study suggests breast cancer treatments lose effectiveness over time

SAN ANTONIO (May 9, 2011) – Some breast cancer treatments designed to reduce the risk of a recurrence may lose their effectiveness once the patient survives the first three-year danger zone, suggests a new study published online today in the Journal of Clinical Oncology.

The paper’s authors examined existing data and hazard curves to come to the conclusion that breast cancer is a chronic disease that may sometimes recur many years after initial diagnosis and treatment, and drug studies should be redesigned to take that into account, said Ismail Jatoi, M.D., Ph.D., at the Cancer Therapy & Research Center at The University of Texas Health Science Center at San Antonio.

“The current paradigm that we have is that these drugs, over the lifetime of the patient, have a constant effect,” said Dr. Jatoi, chief of surgical oncology at the Health Science Center and the paper’s lead author. “What we’ve suggested in this paper is that’s not really the case. What we’re seeing is that some drugs have an initial effect. The effect of the drug diminishes after about three years.”

There’s also some suggestion that immunotherapy, which has not yet been developed for breast cancer treatment, could have a delayed effect, with the benefits not evident for several years. Dr. Jatoi said it would make sense to design trials to follow patients for 8 or 9 years, or possibly begin studies that take patients who are 5- or 7-year breast cancer survivors.

“This is important because we’re seeing more and more long-term breast cancer survivors,” Dr. Jatoi said.


The Cancer Therapy & Research Center (CTRC) at The University of Texas Health Science Center at San Antonio is one of the elite academic cancer centers in the country to be named a National Cancer Institute (NCI) Designated Cancer Center, and is one of only four in Texas. A leader in developing new drugs to treat cancer, the CTRC Institute for Drug Development (IDD) conducts one of the largest oncology Phase I clinical drug programs in the world, and participates in development of cancer drugs approved by the U.S. Food & Drug Administration. For more information, visit

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