High HPV rates highlight importance of screening

Widespread virus will infect more than two-thirds of the population

By Pascal Zamprelli

For most people, sexually transmitted diseases are considered a problem “other people” have to deal with. But many may be surprised to learn that there is one type of infection that over 70 per cent of people will have at some point in their lives, whether or not they are aware of it.

It is commonly known as HPV, which stands for human papillomavirus, and is often found in young, sexually active people. Over a hundred distinct types of the virus have been identified, potentially causing genital warts, and in some cases increasing risk of cervical cancer.

But “most of these infections are asymptomatic; you wouldn’t even know they were there,” said Dr. Ann Burchell,a former PhD student and post-doctoral fellow at McGill’s Cancer Epidemiology Unit and one of the principal authors of a groundbreaking study that explored HPV infections in new young couples – women aged 18 to 24 who are attending university or CEGEP and the male partners with whom they have been sexually involved for less than six months (when transmission is likeliest to occur).

Striking results

The results are striking. More than half (56 per cent) of all participants were infected with at least one HPV type and almost half (44 per cent) were infected with an HPV type that causes cancer.

Published in the January 2010 issues of the journal Epidemiology and Sexually Transmitted Diseases, the results also indicate that HPV is an easy virus to get and to transmit, and that there is a high probability that if you are in a sexual relationship and your partner has HPV, you will get it as well.

Even regular condom use decreases the risk of transmission only slightly, as HPV can be transmitted through skin-to-skin sexual contact, whether or not there is penetration.

But how does one know? “If there is a lesion or a wart present, they should be going to visit their health care provider to have that assessed,” Dr. Burchell said. But since often no such symptom is obviously present, she recommends regular Pap test screening for women.

“The thing that’s of concern is if an HPV infection is causing them any kind of lesion,” she said. “It’s hard to

anticipate which HPV infections are going to be those that produce a lesion, but that’s where Pap test screening is important. If an HPV infection is causing changes to the cells of the cervix that will get picked up in a Pap test. What’s important is that women are in regular care and are getting sreened.”

Dr. Burchell said that while the results are alarming, this must be balanced with a

reassurance that most of these infections aren’t going to cause disease. “Over half of the women had an HPV infection, but the vast majority of these won’t have any clinical disease present,” she said. “But we can’t be complacent because that small proportion that will progress to cause disease – it’s hard to know which women that will include. So we need to be vigilant and women need to be screened.”

If a Pap test suggests an abnormality, there are recommendations and guidelines in place, and a follow-up test may be recommended.

Prevention is key

These types of cancers, Dr. Burchell emphasized, are preventable. “Even if it happens to be that rare case where HPV is causing a disease, the treatments that are available for these pre-cancerous lesions are quite good, and cancer can be prevented. The rates of cervical cancer in Canada are considerably lower than they were before the onset of Pap test screening. Screening works.”

Dr. Burchell’s research is ongoing, and women who fit the target group (women 18-24 attending university or CEGEP and involved in a new relationship within the last six months) are encouraged to participate by visiting www.mcgill.ca/hitchcohort/ or phoning 514-398-8191.