Genetic Test Predicts Breast Cancer Recurrence
Test Helps Determine Need for Chemotherapy
Dec. 4, 2003 (San Antonio) -- A new genetic profiling test can help determine whether women with newly diagnosed breast cancer need to take chemotherapy, researchers say.
"This tool gives considerably more information than standard measures of determining recurrence such as age and tumor size," says Norman Wolmark, MD, chairman of the National Surgical Adjuvant Breast and Bowel Project and of the department of human oncology at Allegheny General Hospital in Pittsburgh.
"Women can then use this information to decide whether they should have chemotherapy. All eligible patients should get it," he says.
The test looks for the presence of about two dozen genes that can raise breast cancer risk. It can accurately predict the likelihood that breast cancer would recur if chemotherapy were not administered.
The findings were presented at the 26th Annual San Antonio Breast Cancer Symposium.
For the study, the researchers analyzed tissue samples collected from 668 women with node-negative, estrogen-receptor positive breast cancer and who were treated with tamoxifen in the 1980s. Breast tumors that are classified as node negative and estrogen-receptor positive are more easily treated than those that have spread at the time of diagnosis and are node positive. These tumors may or may not recur.
In this study, breast cancer tissue samples were sent to a lab for analysis, which looked for the expression of 21 genes involved in breast cancer risk.
Depending on the whether these genes were present, the women were assigned a recurrence score and classified as being at low, medium, or high risk of recurrence.
Women in the low-risk category had only a 6.8% chance of having a recurrence, the researchers showed. But cancer came back in more than 30% of women who fell into the high-risk category.
"Obviously we would have given these women chemotherapy," he says.
Currently, when a woman is diagnosed with breast cancer, her doctor prescribes tamoxifen or a newer class of drugs called aromatase inhibitors, which have been shown to lower the recurrence rate of breast cancer. Estimates of recurrence are based on age, tumor size, and a gene called HER2.
"But our study showed that such clinical characteristics are not particularly accurate compared with recurrence score," Wolmark says. "Now we have an objective test we can use."
Women who have been told they are at low risk of recurrence using traditional measures should not panic, he stresses. "The more time goes by without a recurrence, the lower your risk," he says. "This test is only for the newly diagnosed patient."
Melody Cobleigh, MD, of Rush University Medical Center in Chicago, says she plans to routinely offer the test to her patients once it becomes available.
"We tend to give too much chemotherapy in this country because we can't pick out who really needs it," she says. "Of every 100 women we treat, 85 probably didn't need it in the first place and four will suffer a recurrence despite the treatment. This test has the potential of giving us a very significant piece of information that can help us to avoid unnecessary treatment."