Researchers at the Cancer Institute New South Wales (NSW) have taken a firm step in solving the mystery behind a cancer that also happens to be the state's third deadliest one.
In NSW, about 1500 people a year are diagnosed with the condition, which is called unknown primary site cancer.
It is called so because doctors cannot identify the organ where it originated before it spread around the body.
Jim Bishop, the chief executive officer of the Cancer Institute NSW, said that the study suggested the disease was a distinct type of cancer, perhaps caused by malignant stem cells, rather than known cancers that had spread to other organs.
The study, the first of its kind, also showed that some patients have a better chance of survival than world experts had thought.
"With this new information, doctors and researchers can now explore how this cancer could be diagnosed earlier," Sydney Morning Herald quoted Professor Bishop, as saying.
"The study has also raised the possibility that differences in the genetic make-up of unknown primary site cancer could lead researchers to new discoveries to improve treatment and survival," he added.