A team of researchers in British Columbia, Alberta, the United States and the U.K. mapped the genetic profile of what's called triple-negative breast cancer, the largest genetic analysis of its kind.
A news release from Simon Fraser University, where four of the researchers in the study are based, said the 59 scientists involved in the study expected to see similar gene profiles when they mapped the genomes of 100 tumours.
But they found no two genomes were similar, never mind the same.
“Seeing these tumours at a molecular level has taught us we’re dealing with a continuum of different types of breast cancer here, not just one,” Steven Jones, co-author of the study, said in a news release.
Jones is a molecular biology and biochemistry professor who heads up bioinformatics research at the BC Cancer Agency. He said discovering the genetic diversity of the tumours "probably explains why they are so difficult to treat."
"These findings prove the importance of personalizing cancer drug treatment so that it targets the genetic make up of a particular tumour rather than presuming one therapy can treat multiple, similar-looking tumours.”
The study was published Wednesday in the online edition of the journal Nature.
Triple-negative breast cancer is considered the most deadly form of breast cancer because it doesn't respond well to drugs and requires surgery, chemotherapy and radiation. Patients with that form of breast cancer usually end up having everything thrown at them in an effort to push the cancer into remission.
Prof. Samuel Aparicio, another of the paper's authors who teaches at the University of British Columbia and works at the BC Cancer Agency, cautioned the paper's conclusions won't mean quick changes for anyone in treatment for this type of cancer now.
He said for 15 to 20 per cent of patients, it may mean additional options beyond the current existing treatments.
"The efficacy of these options now needs to be tested directly in clinical trials," he said.
"We didn't know they existed before. We are hoping to do this if we get funded and that would lead to a change in practice if the outcomes were positive."
For the remaining patients, the research gives some indication of the types of drugs that need to be developed to treat the tumours.
"That will take time, but there is a path forward that we can see," said Aparicio.
"The main pointer here is that we will have to learn how to combine drugs from the outset, as is done in treating diseases like HIV for example, where combination therapies have become very successful."
B.C. Labour Minister Margaret MacDiarmid, a past president of the BC Medical Association, was diagnosed with the disease a few years ago and said the discovery is groundbreaking.
"It's an amazing announcement. It's hard not to take it personally because, yes, I did have triple-negative cancer," she said. "I was diagnosed, fortunately for me, at a very early stage. I have no sign of any problems from it, but it is one of the most deadly forms of breast cancer."
She said the announcement gives hope to those suffering from the disease.