People at risk of a tough-to-treat, deadly form of breast cancer may now have a better chance of early diagnosis and protection against relapse.
Researchers at the Mayo Clinic identified genetic mutations associated with triple-negative breast cancer, a type that generally requires extensive chemotherapy and and has lower five-year survival rates than other forms of breast cancer, according to the study published Monday in the Journal of the National Cancer Institute.
"This study is the first to establish which genes are associated with high lifetime risks of triple-negative breast cancer," said lead author and Mayo Clinic geneticist Dr. Fergus Couch.
The researchers analyzed genetic panels of almost 11,000 patients diagnosed with triple-negative breast cancer. Five genetic mutations, BARD1, BRCA1, BRCA2, PALB2 and RAD51D, were linked to a high risk of triple-negative and a 20 percent lifetime risk of any breast cancer. Two other genes were tied to a more moderate risk of triple-negative.
Previous studies have found some of these genetic variants in triple-negative breast cancer patients but the new research establishes the connection in greater detail and identifies two genes linked to triple-negative, RAD51D and BARD1, which were previously thought only to be associated with ovarian cancer, Couch said.
With the new findings, patients diagnosed with triple-negative breast cancer will be able to screen for the associated genes, which may indicate how likely the disease is to recur. If the gene mutations are found, patients would qualify for additional monitoring through MRI and mammography, alternating each one every six months, according to Couch.
Dr. Sandra Swain, who specializes in cancer and genomics research at Georgetown University Medical Center, called the study results significant.
“Triple-negative is hard to treat and has low survival rates, especially in a recurrence," Swain, who was not part of the study, told NBC News. "It’s really exciting discovering more and more genes that can help with treatment."
However, beyond women or men who have been diagnosed with triple-negative, it's undetermined who should be screened for the genetic mutations, Swain said. Over 30 percent of the triple negative patients in the study had no family history of breast cancer and other risk factors aren't well understood.
“Unless we start testing everyone for these genes, it’s unclear how we can effectively screen for first-time cases,” Swain said.
Triple-negative accounts for 15-20 percent of all breast cancer diagnoses. Black women are more than twice as likely to develop this aggressive form than white women. The study found the same prevalence of problematic genes in both groups. Black women, however, were only about 12 percent of the patients in the study.
“Why this is more common in African-American women is something of a mystery,” Couch told NBC News.
But, for now, a crucial piece of the puzzle is in place.
“Some of these genes showed up on genetic panels, and doctors didn’t know what to do with them,” Couch said. “Now, they won’t be ignored, and patients will benefit.”