Queensland scientists have identified a genetic "switch" which indicates whether breast cancer is aggressive and likely to spread.
The discovery may provide a clearer prognosis for breast cancer patients and pave the way for new treatments.
Teams from QIMR Berghofer Medical Research Institute and the Institute of Molecular Bioscience (UQ) have found a particular RNA (Ribonucleic acid) molecule goes missing in aggressive cancers.
QIMR Berghofer's Dr Nicole Cloonan says the discovery will make it easier to identify aggressive tumours.
"Essentially, this particular gene fragment, or microRNA, normally acts like an emergency brake in our genetic program, ensuring our cells continue to reproduce normally," Dr Cloonan explained.
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"But we've identified that this "emergency brake" fails in invasive, aggressive tumours. Its sudden absence in cancer tests would be a clear marker that a tumour is likely to spread.
"And we know that primary breast cancer rarely kills; it is those aggressive tumours that spread, or metastasise, which result in poor outcomes."
Breast cancer is the most common cancer in Australian women.
Survival largely depends on the timing of diagnosis. If the cancer is limited to the breast, 96 per cent of patients will be alive five years after diagnosis, according Cancer Council Australia.
Dr Cloonan says, although the research focused on breast cancer, it has wider implications.
It is clear the microRNA is also missing in aggressive liver, stomach, brain and skin cancers, she said.
"What we've uncovered seems to be a common cellular process which could be a new drug target," Dr Cloonan said.
