US test may miss breast cancer traits
More than 1 in 10 women who test negative for a genetic trait linked to breast cancer may still get the disease because of undetected abnormalities, scientists say.
The testing commonly used in US hospitals may not find all parts of the so-called BRCA1 and BRCA2 breast cancer genes that make a patient more likely to get the disease, said a study released today at a panel on women's health issues held by the Journal of the American Medical Association in New York.
''Our results suggest that genetic testing, as currently carried out in the United States, does not provide all available information to women at risk," wrote researchers, including Mary-Claire King, a geneticist at the University of Washington in Seattle. King was instrumental in helping uncover the existence of the breast cancer genes.
The scientists tested DNA samples from more than 300 people with at least four cases of breast or ovarian cancer in their families. All proved negative for BRCA1 and BRCA2 abnormalities when tested with the process used in US hospitals, the study found.
A closer examination using other tests recommended by the study authors -- including one that isn't available in the United States -- found mutations in the BRCA1 or BRCA2 genes that other tests missed in 12 percent of subjects, the study says. A further 6 percent had abnormalities in other genes that predisposed them to breast cancer.
More than 212,920 women will be newly diagnosed with invasive breast cancer in the United States this year, and 40,970 patients will die, according to the Susan G. Komen Breast Cancer Foundation, a Dallas-based nonprofit.
The BRCA1 and BRCA2 genes can contain thousands of mutations, the study says. Abnormalities appear in 5 percent to 10 percent of patients with breast cancer, said Cheryl Perkins, senior clinical adviser for the Komen foundation.
''There are many other genes related to an increased risk of breast cancer," Perkins said in an interview yesterday.
''As we understand the difference in women's breast cancers, we can individualize and target the medicine," she said.
Increased identification of gene traits that predispose a person to breast cancer could help women and their doctors decide whether an invasive surgical procedure is needed to prevent or detect the disease, the study says.
''Women at high risk and their clinicians want accurate assessment of genetic risk prior to embarking on such invasive and expensive risk management options," the study says.
Nearly all commercial tests used in the United States to analyze BRCA1 and BRCA2 genes are made by 
