Aspirin and other household drugs may inhibit the spread of cancer because they help shut down the chemical "highways" which feed tumours, Australian researchers said Tuesday.

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.

Once these lymphatic vessels widen, the capacity for them to act as "supply lines" to tumours and become more effective conduits for the cancer to spread is increased.

But aspirin acts to shut down the dilation of the vessels.

"So it seems like we have found a pivotal junction point in a biochemical sense between all these different contributors," Stacker said.

The discovery could lead to new and improved drugs which could help contain many solid tumours, including breast and prostate cancer, as well as potentially provide an "early warning system" before a tumour begins to spread.

Last year, a study published in medical journal The Lancet found that rates of cancer of the colon, prostate, lung, brain and throat were all reduced by daily aspirin use.

Many doctors recommend regular use of aspirin to lower the risk of heart attack, clot-related strokes and other blood flow problems. A downside of extended daily use is the risk of stomach problems. (AFP)