A vaccine that fights cervical cancer should be administered to as many girls as possible between the ages of 12 and 16, before they engage in sexual activity.

Asserting this yesterday, Professor Harald zur Hausen, winner of the Nobel Prize for Physiology or Medicine, said doing this could do much to cut the large number of women who contract the disease every year. However, he said that though 'in general, every girl should be vaccinated', whether or not this is done should be her choice alone.

What is more important, he said, was to encourage and educate girls on the risks of cervical cancer.

Prof zur Hausen, who won the Nobel Prize for his discovery that human papilloma viruses cause cervical cancer, was the keynote speaker at a forum on the infectious causes of human cancers held yesterday. He said that administering the vaccine later in life, after a woman has had a few sexual partners, is next to useless.

'If a woman has had several sexual partners, chances are her cells are already infected, in such an instance, a vaccination will have no effect whatsoever,' he said.

Professor Soo Kee Chee, head of the National Cancer Centre, agreed with this view. Speaking at the same forum, Prof Soo said that 12 to 16 was a 'reasonable' age range for getting vaccinated. He based this on what he called anecdotal evidence that young people are engaging in sex earlier.

Police figures for last year indicated that 310 girls younger than 16 engaged in underage consensual sex, nearly 45 per cent more than the previous year.

Cervical cancer is now the sixth most common cancer among women here, down from its No. 2 ranking in 1968. Prof Soo put the decline down to the rise in other forms of cancer and the fact that more women are getting Pap smears nowadays, the gold standard screening method for sexually active women.

Cervical cancer, which kills 300,000 women globally every year, is caused by the human papilloma or wart virus, which is passed mainly through sexual contact.

Every two days here, at least one woman learns she has cervical cancer; every five days, one woman dies from it.

There are now two anti-cancer vaccines on the market - Cervarix and Gardasil. They can potentially prevent 70 per cent of cervical cancers. The drawback: Their high price tags. For example, the price of Cervarix was cut by 30 per cent this month, but a three-jab course still costs around $450.

Fewer than 1 per cent of the 1.8 million women here aged between 10 and 25 have gone for it, a December 2008 survey of 200 women by the Obstetrical and Gynaecological Society of Singapore found. Lack of awareness is one reason, and this should be addressed, said Prof Soo.