Australian scientists have discovered how anti-inflammatory drugs such as aspirin prevent tumors from spreading.

The breakthrough by researchers at Melbourne's Peter MacCallum Cancer Centre paves the way for new treatments to halt cancer in its tracks.

While the benefits of non-steroid anti-inflammatories on cancer were known, the biological processes involved had never been fully understood.

Co-lead author Tara Karnezis said tumors secret proteins and compounds called growth factors, attracting blood and lymphatic vessels to their vicinity and allowing the cancer to flourish and spread. These growth factors also encourage lymphatic vessels -- or "supply lines" -- to widen, which enables the spread of cancer, she added.

"But a group of drugs reverse the widening of the supply line and make it hard for the tumor to spread -- at the end of the day that's what kills people," Karnezis said.

"This discovery unlocks a range of potentially powerful new therapies to target this pathway in lymphatic vessels, effectively tightening a tumor's supply lines and restricting the transport of cancer cells to the rest of the body."

While oncologists may include aspirin in patients' treatment, this discovery enabled the development of better and more efficient drugs, she said.

The research is published in the journal Cancer Cell.

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