September 28th, 2010
03:55 PM ET
Researchers may have found a new lead toward treating triple negative breast cancer, a rare and aggressive form of the breast cancer that occurs more often in younger women and African-American or Hispanic women.
A study looks at insulin-like growth factor 1 receptor (IGF-1R), which has been shown to be involved in several cancers, including more common types of breast cancer. But no study has focused on its role in triple negative breast cancer before. The findings were presented at the Fourth AACR International Conference on Molecular Diagnostics in Cancer Therapeutic Development on Tuesday.
"There is a desperate need to better understand this cancer and find potential new targets for treatment," said study author Dr. Agnieszka Witkiewicz, associate professor of pathology at Thomas Jefferson University Hospital in Philadelphia, Pennsylvania.
There are about about 207,090 new cases of invasive breast cancer in women each year in the United States, according to the latest information from the American Cancer Society. Between 10 to 20 percent of breast cancers are triple negative, according to breastcancer.org.
Receptors are proteins on the surface of cells which receive signals to grow. Specific types of receptors on cancer cells indicate what is fueling the cancer.
The diagnosis of most breast cancers involves three types of receptors: estrogen receptors, progesterone receptors and human epidermal growth factor receptor 2 (HER2). But in triple negative breast cancer, estrogen and progesterone receptors are not present in the cancer cells, and there is not an excess of the HER2 protein on the cells' surfaces.
That means that patients with triple negative breast cancer will not respond to treatments targeted at those receptors. Chemotherapy can help, but this is form of breast cancer often takes an aggressive course, and has a high likelihood of recurrence.
Witkiewicz's study showed that IGF-1R was overexpressed, or present in excessive amounts, in 25 percent of cases, meaning this protein could be a potential therapeutic target. Participants included 73 white and 24 African American patients.
Overexpression was associated with longer survival in patients under 55 years old. This high expression was somewhat associated with low tumor size; low expression carried a greater risk of lymph node metastasis.
There are already several clinical trials involving drugs called IGF-1R inhibitors that could be relevant for triple negative patients, based on the findings of this study, Witkiewicz said. After more patients are analyzed, researchers could look at clinical trial data to see if the response to the drugs is associated with IGF-1R overexpression. In other words, this particular protein may be predict how well a patient responds to drugs in clinical trials.
In most studies of breast cancer, patients with triple negative are underrepresented, she said.
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