Cancers have been successfully frozen to the brink of death, enabling them to be wiped out with powerful drugs, researchers said yesterday.

The tumours are killed by inserting ice-cold metallic probes to freeze the cancerous cells. Once frozen, the outer barriers of the cells become leaky, allowing large molecules such as anti-cancer drugs to pass through the cell membranes.

Researchers from France and America believe that the technique, called cryochemotherapy, will prove highly potent as well as more selective than conventional treatments. A report in the British Journal of Cancer yesterday said that the frozen probes could be precisely directed, leaving healthy tissue unharmed.

Until now, procedures using freezing have had limited success because the survival of even a handful of cells means that the tumour can regrow.

But Dr Lluis Mir, from the Gustave-Roussy Institute near Paris, and Dr Boris Rubinsky, from the University of California at Berkeley, decided to combine freezing with chemo-therapy. They treated frozen cancer cells with a drug called Bleomycin, which is potentially highly toxic to cells, but is usually unable to pass through their membranes. Their experiments showed that hardly any cancerous cells survived the combined treatment.

Dr Mir said: "Frozen tissues show up very clearly on scanning images, so it is a simple matter to ensure you are giving the cold probes to the tumour and avoiding the healthy tissue. Although the drug we are using is extremely toxic, it can only enter cells that have been frozen, which means that unfrozen healthy tissue will be left unaffected."

Preclinical trials are due to start shortly, but Dr Mir said the treatment would not be available for patients for some time.

* Cancer-causing chemicals have now overtaken heart disease as the number one killer of Europeans aged between 35 and 65, MPs were warned at a Commons meeting. Dr Claude Reiss, a molecular toxicologist, said experts agreed that 80 to 90 per cent of cancers – 1 million casualties per year in the EU – were attributable to carcinogenic chemicals present in the environment.

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