Scientists at Melbourne's Peter MacCallum Cancer Centre said they have made a biological breakthrough helping explain how lymphatic vessels - key to the transmission of tumours throughout the body - respond to cancer.

"We've shown that molecules like the aspirin could effectively work by reducing the dilation of these major vessels and thereby reducing the capacity of tumours to spread to distant sites," researcher Steven Stacker said.

Doctors have long suspected that non-steroidal anti-inflammatory drugs such as aspirin may help inhibit the spread of cancer but they have been unable to pinpoint exactly how this is done.

By studying cells in lymphatic vessels, the researchers found that a particular gene changed its expression in cancers which spread, but not when the cancer did not spread.

The results published in Cancer Cell journal reveal that the gene is a link between a tumour's growth and the cellular pathway which can cause inflammation and dilation of vessels throughout the body.