An experimental treatment designed to stimulate the immune system to fight breast cancer appears to reduce the risk of death by half, a study shows.

Research conducted by the US military found the vaccine, designed to treat women with tumours generating HER-2, caused the risk of death to fall by half at a 30-month follow-up, however scientists stressed this could be due to chance.

The results of the small-scale trial have led to the issue of a license for the vaccine from the US military to biotechnology company Apthera Inc, under the brand name NeuVax.

Researchers at Brooke Army Medical Center in San Antonio tested NeuVax in patients whose tumours generated low levels of HER-2 alongside women who showed high levels of the protein.

After 30 months the injected vaccine cut the risk of death for all patients by half, while in the group of patients with low-expressing HER-2 tumours no deaths were reported.

Cancer recurrence was recorded in 10.7 per cent of patients with low-expressing HER-2 tumours, compared with 18.2 per cent in the control group.

The vaccine will now be tested in a Phase III trial in more than 700 patients with tumours generating low levels of HER-2.

Speaking to Bloomberg, William Hait, president of the American Association for Cancer Research said he was "cautiously optimistic" about the research.

"The difficulty in interpreting the data is that patients with lower amounts of HER-2 have a better prognosis to begin with,' he explained.

The findings were presented at the American Association for Cancer Research meeting in San Diego.

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