Scientists announced Sunday that they have finished mapping almost all of the genetic mutations of breast cancer, USA Today reports. The researchers have redefined breast cancer into four main classes, and found that one of the most lethal types of breast cancer is similar to a more aggressive type of ovarian cancer.
Brad Ozenberger, the overseer of the Cancer Genome Atlas research project at the National Institutes of Health, said, “Just because it’s a breast cancer doesn’t mean it’s like every other breast cancer.”
Study co-leader Matthew Ellis of the Washington University School of Medicine in St. Louis said women with basal-like breast tumors would likely benefit from a less toxic chemotherapy regimen, which is the standard in treating ovarian cancer.
According to Ellis, the scientists analyzed tissue from 348 breast cancers and found that most tumors are caused by mutations in 30 to 50 genes.
Breast cancers were previously divided into three primary groups for treatment purposes, but the new research may change the way doctors look at the subcategories of the disease.
Dr. Christopher Benz, an oncologist at the University of California at San Francisco said, “We’re going to move farther and farther from the practice of classifying cancers by where they arise and more and more by what their molecular composition and wiring is all about.”
Ozenberger said the research could give drug companies new ideas for drugs that target key genetic mutations. He also said the catalogue could help scientists better understand how cancers develop and spread.
There are 1.3 million new cases of breast cancer and 450,000 deaths worldwide each year. Triple-negative breast cancer, which lack the hormone receptors estrogen and progesterone, account for 10 to 15 percent of all breast cancers, and are more common among African-Americans and younger women.
Women with triple-negative tumors are treated like many other breast cancer patients, but the research found that the treatments that are often used do not help in those cases. Instead, doctors should consider using a type of drug called PARP inhibitors, which had promising results in ovarian cancer trials. BRCA1, one of the best known breast cancer genes, dramatically increases the risk of both ovarian cancer and triple-negative breast tumors.
The findings of the study were published in the September 23 issue of Nature.