The compound that gives curry powder its distinct yellow colour has killed cancer cells in the lab, Irish and Polish researchers report.

When scientists treated esophageal cancer cells with curcumin, found in the spice turmeric, it started to kill the cells within 24 hours, the team reported in Wednesday's issue of the British Journal of Cancer.

Curcumin has long been suspected of having therapeutic properties including anti-cancer value.

In the study, the treated cells also began to be digested, said Sharon McKenna of the Cork Cancer Research Centre, lead author of the study. Normally, cells die by committing programmed cell death or apoptosis.

Usually, proteins called caspases trigger cell suicide. But the cancer cells treated with curcumin showed no evidence of this.

Adding a molecule that blocks caspases triggering suicide also made no difference to the number of cells that died.

Added together, the evidence suggests that curcumin triggered cell death using an alternative cell signaling system, the researchers said.

Cancers of the esophagus kill more than 500,000 people across the world each year. The tumours are especially deadly, with five-year survival rates of 12 to 31 per cent.

It's estimated there will be 1,600 new cases of the disease in Canada this year, according to the Canadian Cancer Society.