A vaccine to prevent cervical cancer could be available to women in Britain within a year.

A pharmaceutical firm has trialled a new drug, Gardasil, which has proved 100 per cent effective in blocking a major cause of cervical cancer, which kills 1,500 women in Britain every year.

The dramatic results of the trial have been described as "stunning" and "exciting" by Professor Margaret Stanley, an expert in the human papilloma virus (HPV) at Cambridge University. Gardasil is designed to protect against two strains of the virus, which trigger 70 per cent of cervical cancers.

The vaccine not only acts against the HPV 16 and 18 strains, but also against the strains six and 11, which cause genital warts.

Cervical cancer kills 274,000 women worldwide every year - and is the second most prevalent form of cancer in women in their twenties, thirties and forties. Women are encouraged to have smear tests every three years for warning signs that the cancer is developing. HPV is sexually transmitted and carried by 15 per cent of women in their thirties. Although teenagers and adults took part in the trials, the vaccine is likely to be administered to girls as young as 10 to 13 who are free of the virus.

A total of 12,167 women aged 16 to 23 from 13 countries, including the UK, took part. Half were given three injections of Gardasil spanning six months and half jabs of an inactive dummy drug. They were then monitored for an average of two years. None of the women were infected with HPV at the start of the trial and they remained infection free throughout treatment.

Similar results were seen in a smaller trial of 277 women. The new study, Future II, is part of a phase III trial programme involving more than 25,000 patients in 33 countries.

Professor Stanley said: "We now have evidence that Gardasil is effective against the advanced-stage abnormalities of the cervix, called lesions, that lead to invasive cervical cancer.

"The smaller-scale preliminary HPV vaccine trials published to date have only indicated that this may be the case, but this study gives us very solid evidence. The results of Future II are so exciting because of the sheer size of the trial and the fact that it demonstrated 100 per cent efficacy."

Some critics have argued that administering a vaccine against a sexually transmitted disease on children so young is encouraging underage sex, but with 15,000 a year in Europe dying from the disease, the vaccine is likelyto be widely welcomed.

Gardasil's manufacturers are on track to apply for a US Food and Drug Administration licence to market the vaccine before the end of this year. This will be followed by a licence application to the European Medicines Agency.

The vaccine is a joint venture by the pharmaceutical companies Sanofi Pasteur and Merck. It is in competition with another HPV vaccine from GlaxoSmithKline called Cervarix, which is also undergoing trials. The vaccines could be among the biggest-selling drugs of all time. One analyst has estimated that Gardasil could be worth $1bn (£570m) a year.

Professor Peter Rigby, the chief executive of the Institute of Cancer research, said: "These results are extremely encouraging.

"It is exciting to hear that it may be possible to dramatically reduce the number of people diagnosed with cervical cancer in the forseeable future."

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