TORONTO (CP) -- New research may kick-start the debate over male circumcision.

Women whose sex partners are circumcised appear to be less likely to develop cervical cancer, according to a large international study. The reason is that circumcised men are less likely to become infected with and pass on to their partners the human papillomavirus.

Human papillomavirus, known as HPV, is a common sexually transmitted disease. It causes genital warts in men and women and has been linked to cervical cancer as well as cancer of the vulva, vagina, anus and penis.

The protective effect of circumcision is greatest among women whose partners put them most at risk because of their sexual behaviour -- men who have had multiple (at least six) sexual partners, men who became sexually active at a young age and men who have sex with prostitutes.

"The most striking finding for us . . . (is) that the higher the sexual behaviour risk of the men, the higher the protection of circumcision for cervical cancer in their wives," said lead author Dr. Xavier Castellsague, of the Catalan Institute of Oncology in Barcelona, Spain.

Castellsague and his colleagues studied data from seven studies on cervical cancer in the Philippines, Spain, Columbia, Thailand and Brazil and reported their findings Thursday in the New England Journal of Medicine.

Those studies were conducted under the auspices of the International Agency for Research on Cancer.

Men who were either the stable partner or husband of women in the studies were interviewed by Castellsague and his team. They were asked about their sexual behaviour and whether they were circumcised, and were checked for HPV infection.

Uncircumcised men were three times more likely to be infected with the virus.

Among men whose sexual behaviour was considered high risk, those who were uncircumcised were five times more likely to carry the virus.

It is not entirely clear why circumcision protects men from acquiring HPV, but it is believed that the inside surface of the foreskin is not as tough as skin elsewhere on the penis and is thus more vulnerable to the virus.

It is also believed that circumcision protects men from acquiring and passing on other sexually transmitted diseases, including HIV.

An editorial in the journal calls the study findings "convincing" and suggests an increase in the circumcision rate globally might have public health benefits.

But Castellsague and his colleagues were not ready to call for a widespread return to circumcision.

"This paper is just presenting the scientific data of a very large and very powerful study that circumcision is reducing HPV in the penis and also cervical cancer in the wives. But we are not making recommendations because it's very controversial," he said in an interview.

He suggested a debate on the pros and cons of circumcision should take place.

"It seems that indeed the data and the evidence are very consistent that circumcision may protect or may reduce the risk of acquiring any STDs, including HIV and HPV," he said.

"But I would move away from making recommendations. What I would say in this report is that a systematic, scientific review of the evidence is urgently needed at this point."

Once done as a matter of course in North American hospitals, circumcision has fallen from favour in the past couple of decades. Critics argue there is no good reason for snipping off an infant's foreskin. Even the Canadian Paediatric Society terms the procedure "not medically necessary," although it recognizes circumcision remains important among some cultures.