Mice vaccinated with stem cells have proved to be resistant to lung cancer.

The findings, announced yesterday at a conference in Prague, suggest the possibility of developing embryonic stem-cell vaccines that prevent cancers in humans.

John Eaton, of the University of Louisville, told the meeting that the vaccinations were 80 to 100 per cent effective in preventing cancer growth in mice after they had been given transplanted tumours. The vaccinations had also proved 60 to 90 per cent effective in mice exposed to the carcinogens that caused lung cancer.

Professor Eaton said: “Cancer has been prevented and even cured in mice hundreds of times.” The work was in its early stages, though, and people should not think that a lung cancer vaccine was just around the corner.

But he added: “Unless something unexpected happens, this strategy might some day be applied to humans who are at high risk.”

Why vaccinations with embryonic stem cells work is unclear, but it may be that they improve the ability of the lining of the lung to repair itself when damaged by carcinogens, or improve the ability of the immune system cells to identify cancers and hunt them down.

Professor Eaton said: “If all goes well, then I think this vaccination might best be tested in women at high genetic risk of breast cancer, in people with high genetic risk of colon cancer and perhaps in smokers.”

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