Good news on cancer vaccine

An international trial of the cervical cancer vaccine planned to go on sale in New Zealand this year has shown it protects women who have already been exposed to the cancer-causing virus.

Earlier results from the trials of more than 12,000 women and girls have shown Gardasil is protective for those not yet exposed to the four types of sexually transmitted human papilloma virus covered by the vaccine.

On the strength of those results, it is intended to market the vaccine for use in girls as young as 9 so they are protected before they become sexually active and potentially infected with the virus, HPV.

The new results, presented to a conference in Paris this week, suggest the vaccination may also be beneficial for older women who are sexually active and have been exposed to any of the vaccine's four HPV types.

"This is all good news," said Family Planning Association clinical spokeswoman Dr Christine Roke.

"It is exciting that we have got something that appears to be able to prevent women from catching the wart virus, if they haven't already, or getting the complications of it."

There are more than 100 known types of HPV, of which more than 20 can infect the genital tract. Virtually all cervical cancer is linked to HPV infection.

Two of the HPV types Gardasil is designed to protect against are linked to cancer and two to genital warts.

The two cancer-linked HPV types are associated with 70 per cent of cervical cancers.

About 180 New Zealand women are diagnosed with cervical cancer each year and 60 die from it.

Eighty per cent of the population is exposed to genital HPV at some point, although many people will never know, as they have no visible symptoms. Most people's immune systems get rid of the virus, but a small percentage develop persistent infections.

HPV is also linked to other genital cancers and anal cancer and the vaccine is being tested on males.

Merck, the drug company making the vaccine against HPV types 6, 11, 16 and 18, says the latest research on more than 4000 women shows it provided "high-level protection" for women already infected with one or more of those four virus types, but only for the virus types with which they have not been infected.

The vaccine prevented 88 per cent of all grades of cervical cell changes related to the four HPV types, 91 per cent of genital warts and other external genital lesions, and 100 per cent of high-grade cervical pre-cancers and non-invasive cancers.

Merck says the significance of this is that it will be impractical to test each patient for HPV infection before vaccination.

"This data shows that a woman does not need to be completely free of HPV infection to get protection and benefit from Gardasil."

But because of the risk that sexually active women might previously have been infected with a cancer-linked HPV type, they will be advised to have regular cervical screening.

David Bowler, chief executive of CSL, the company which intends to market Gardasil in New Zealand, said he expected it to go on sale this year.