New Clue to Breast Cancer Mortality
Growth factor identified with poorer outcomes in patients
SATURDAY, Dec. 6, 2003 (HealthDayNews) -- A substance called epidermal growth factor receptor, which has been associated with higher mortality rates in cancers of the head and neck, has now been linked to higher death rates in breast cancer patients.
The finding may shed light on why some women with breast cancer have higher mortality rates than others, say doctors at the University of Texas M.D. Anderson Cancer Center.
"Our data finding that EGFR-positive breast cancer tumors have worse outcomes is an important discovery that, if validated by other studies, really justifies clinical trials that specifically target the EGFR pathway in those patients whose tumors are EGFR-positive," says study author Dr. Thomas Buchholz, an associate professor of radiation oncology at the M.D. Anderson Cancer Center.
Buchholz is to present his findings this weekend at the San Antonio Breast Cancer Symposium.
Dr. Kimberly Blackwell, an assistant professor of oncology at the Duke Comprehensive Cancer Center, says, "This is an important study because it confirms what other people have reported in the past year, and offers hope that with the new drugs coming down the pike, this will offer benefits to patients who express EGFR."
Buchholz and Blackwell say that 20 percent to 33 percent of women with breast cancer exhibit EGFR, a cell surface receptor.
For the study, Buchholz and his colleagues used preserved tissue samples of 82 women with breast cancer from the years 1989 to 1996 to test for EGFR. Testing for EGFR was not -- and still isn't -- part of normal protocol for breast cancer patients, Buchholz says.
EGFR expression was positive in 14 -- 16 percent -- of the cases, and negative in 68 -- 84 percent -- of the cases. The researchers then compared the survival rates of the two groups and found the EGFR-positive patients had an overall survival rate at nine years of 43 percent, compared to a 60 percent survival rate for the same time period for those who tested negative for EGFR.
"This was a pretty small study, and shouldn't be over-interpreted until the data is validated further. Women shouldn't be asking their oncologists if they should be tested," says Buchholz, "but the results were statistically significant."
Buchholz says the good news is there are a number of drugs in clinical trials aimed at inhibiting EGFR.
"It is hopeful because there are developed compounds to treat it," he says. One trial, to be led by M.D. Anderson and conducted at 15 centers nationwide, will test the EGFR inhibitor drug Iressa, combined with another drug.
Breast cancer is the most common cancer facing American women after nonmelanoma skin cancers, and is the second leading cause of cancer death among women after lung cancer. This year, 211,300 women will be diagnosed with the disease and about 40,000 will die from it, according to the American Cancer Society.
The cancer society reports, however, that the death rate from breast cancer has declined steadily over the last decade, approximately 2.5 percent annually, a drop attributed to both early detection and better treatments. More than 90 percent of the cancers are now diagnosed in the beginning stages of the disease, when the five-year survival rate is 97 percent.