A new study by a joint team of Canadian and British cancer researchers has broken what is commonly understood as breast cancer into effectively 10 different diseases based on the way the tumors' genes mutated.
British and Canadian cancer researchers have isolated a new way of classifying breast cancer into 10 different types, in a breakthrough that cancer experts say could begin to revolutionize how patients are treated.
With their study, published in the journal Nature on Wednesday, the team studied the breast cancers of 2,000 women in great detail and analyzed the way the genes in the tumor cells had changed when the cells became cancerous.
They concluded that all the different types of genetic changes could all be grouped into 10 categories, BBC News reported.
"Breast cancer is not one disease but 10 different diseases," said the lead researcher, Dr. Carlos Caldas, a breast cancer geneticist at the University of Cambridge.
"Our results will pave the way for doctors in the future to diagnose the type of breast cancer a woman has, the types of drugs that will work and those that won't, in a much more precise way than is currently possible," he said. "If you belong to one group you'll need one therapy, and if you're in another you'll need another."
That could mean that many women might not need as aggressive a treatment — for instance, chemotherapy or various hormone treatments — as they are often given under current guidelines.
Those treatments are often given when they may not provide much benefit in instances where doctors don't completely understand the nature of a particular cancer case or how best to treat it, the Los Angeles Times reported.
"A lot of women are being overtreated," Dr. Caldas said. "Can we spare them that?"
Dr. Caldas' team likened its isolation of more particular breast cancer subtypes — which reinforced already known types and further distinguished cancers within them — to the act of subdividing continents into specific countries.
Other breast cancer researchers and groups said they had high hopes that the results of the research could begin to revolutionize diagnosis and pave the way for more individualized treatment plans.
"This is going to have a huge impact on the way we think about breast cancer," Harvard Medical School genetics professor Raju Kucherlapati told the L.A. Times.
"This is the essence of personalized medicine — tailoring treatments to the genetics of a disease," a BBC News analyst said of the study, funded by Cancer Research UK.
After the landmark study from Dr. Caldas' team, breast cancer experts are awaiting the results of two other highly anticipated British studies on breast cancer that are expected to complement the new findings, according to the L.A. Times.