Test Could Spare Women From Chemotherapy
Up to 40,000 Women a Year Can Safely Skip the Toxic Drugs
Dec.10, 2004 (San Antonio) -- A test that characterizes each breast tumor by its unique genetic fingerprint could spare tens of thousands of American women from the discomfort and misery of chemotherapy, researchers report.
About half of the 70,000 to 80,000 women diagnosed each year with estrogen-dependent breast cancer -- that has not spread to the lymph nodes -- can safely skip the drugs, says Norman Wolmark, MD, chair of the National Surgical Adjuvant Breast and Bowel Project and of the department of human oncology at Allegheny General Hospital in Pittsburgh.
"The test helps solve the real dilemma of whether to treat a woman with chemotherapy," he tells WebMD.
The test, known as OncotypeDX, which came on the market earlier this year, looks for the presence of about two dozen genes that can raise breast cancer risk. Based on their activity, women are assigned a recurrence score that determines the risk of breast cancer returning.
Studies have shown the benefit of tamoxifen and chemotherapy in women with estrogen-sensitive breast cancers that have not spread to lymph nodes. The treatment reduces the risk of breast cancer recurrence.
Yet the researchers say that since the likelihood of cancer recurring in tamoxifen-treated women is low, many women would be overtreated if chemotherapy is given to everyone.
Wolmark's first study, published online today in The New England Journal of Medicine, shows OncotypeDX can reliably predict whether a woman's breast cancer recurrence risk is low, medium, or high.
The test relies on the molecular signature of the breast cancer tissue, and based on an assigned score, can predict the likelihood of recurrence in women with estrogen-sensitive breast cancer that has not spread to lymph nodes.
The study showed that the recurrence score accurately predicted the risk of cancer recurrence, Wolmark says. Women in the low-risk category had only a 7% chance of having a recurrence at 10 years. But cancer came back in more than 30% of women who fell into the high-risk category.
Then the researchers looked at 650 women who received either tamoxifen alone or tamoxifen plus chemotherapy.
In those women with a low recurrence score, the risk of cancer spreading to other parts of the body -- what doctors call distant recurrence -- was only about 5%, regardless of whether chemotherapy was given.
But in women at high risk, there was a clear benefit: About 88% of those who got the one-two punch with chemotherapy and tamoxifen were free of cancer 10 years later, compared with only 60% of those who got tamoxifen alone.
And women at intermediate risk? The benefits are still unclear, the experts say, adding this group will be studied more in a new National Cancer Institute trial.
In the meantime, Wolmark urges eligible women to have the test. "Women should find out their risk of recurrence," he says. "Based on that risk, they can make a more informed decision about whether or not to move ahead with chemotherapy
His second study, presented here today at the annual San Antonio Breast Cancer Symposium, shows that the 50% of women who fall into the low-risk category gain little if any benefit from chemotherapy.