WASHINGTON — Eagerly anticipated research results released Wednesday indicate that two recently discovered "breast cancer genes" play a less important role in cancer than scientists had presumed.
Women who inherit faulty versions of the two genes, called BRCA1 and BRCA2, are less likely to get breast or ovarian cancer than previous studies had indicated, and the mutations are present in a smaller number of breast cancers than had been anticipated, according to the new work.
Experts said the findings complicate an already dauntingly complex picture of the role of genes in breast and ovarian cancer. Most immediately, they suggest that expensive tests for these genes, which have become increasingly available commercially, may have less medical value than had been believed for most women.
"At this time we cannot predict an individual's risk based on genetic testing alone," said Margaret A. Tucker, who with Jeffrey P. Struewing, both of the National Cancer Institute, led a Washington-based study of more than 5,000 people to assess the risk of cancer conferred by the two genes.