A chemical found only in breast milk helps break up tumours into fragments in the body, allowing cancer patients to pass them through their urine, trial results have shown.

Alpha1H usually helps in the production of lactose - the nutritious milk sugar produced by mothers which is essential for development in babies.

But scientists have discovered that it can also morph into a different form which can kill tumours, and hope that it could cure patients.

First results from an early trial involving 40 patients with hard-to-treat bladder cancer found all 20 who were given the drug rather than placebo, in six infusions over 22 days, excreted whole tumour fragments in their urine.

In a smaller human trial nine bladder cancer patients were administered five daily doses in the week before surgery to remove their tumour.

Eight out of the nine started passing tumour cells in their urine just two hours after being given the drug, and their tumours reduced in size or aggression. And unlike other methods of chemotherapy there was no damage to surrounding tissue.

The trial was carried out by at Motol University Hospital in Prague and overseen by scientists from Lund University in Sweden.