WHAT TO TELL YOUR PATIENTS

Stop this silent killer before it strikes again

Is it time to make HPV testing as standard as the Pap?

By Jadzia Jagiellowicz

 

HERE'S WHAT TO TELL YOUR PATIENTS ABOUT HPV INFECTION HPV infection is very common. One in four women will contract it soon after they begin sexual activity. There are many strains of HPV infection. Fifteen of them cause cervical cancer. HPV infection is acquired by normal sexual activity and is influenced by factors that reduce the immunity of the cervix such as smoking, a diet lacking in fruit and vegetables, number of pregnancies, prolonged use of oral contraceptives and genetic factors. Over 90% of women will get rid of an HPV infection within one to two years without it causing cervical cancer or precancerous conditions. There is no treatment for HPV infection, although the dysplastic lesions caused by the infection can be treated. HPV infections are more common in younger women than in older women. In patients with compromised immune systems due to HIV infection, cancer can progress much more quickly.

Thirty-three year old Tracy Smith has always been pretty good about going in for her annual Pap test, and luckily the results always came back negative. Until this year, that is. A few months ago she got the dreaded call telling her that her latest Pap showed an abnormality. Her doctor immediately ordered a human papillomavirus (HPV) test; it came back positive, and a colposcopy revealed that she had cervical cancer. Devastated, Ms Smith did a little research on her own and came across some research highlighting HPV's link to cervical cancer. Now she's wondering: "Why wasn't the HPV test done earlier?"

That's a question Dr Eduardo Franco, Director of the Division of Cancer Epidemiology at McGill University, for one, would love to be able to answer. "HPV infection is the essential sine qua non cause of cervical cancer," says Dr Franco. The problem, however, is "there's no standard of practice saying that you should be testing for HPV," he says. "And for women with a negative Pap, there's no standard of practice for what you do with HPV results."

"Once a woman develops a persistent infection with the so-called oncogenic types of HPV, it's possible to detect traces of the DNA of the virus in the same cells of the cervix that are destined for the Pap smear," says Dr Franco. Persistent infection with the HPV virus can lead to changes in the cell walls of the cervix. "Cancer is a very slow process," he says, and it generally takes two to six years for HPV to cause dysplastic lesions of the cervix. "This is what you eventually find in the Pap smear." If cervical dysplasia is left untreated, in five to 10 years it can invade the connective tissue. This time frame reflects the average progression of the disease in most women.

Tracy may have had the carcinoma for some time before it was diagnosed. The sensitivity of the Pap test -- the probability that the test will correctly diagnose cervical dysplasia or carcinoma in women with the disease -- is only 50%, according to Dr Franco. This is why the test needs to be repeated yearly -- to up the chances that cervical dysplasia or carcinoma will be correctly diagnosed at an early stage. The high false-negative rate of Paps has some wondering if HPV screening should be included in the test.

The jury's still out, but some experts are already saying a cautious yes. A recent British study, headed by Cancer Research UK, and published in The Lancet showed that HPV testing is more specific in detecting cervical cancer than the Pap. HPV testing correctly diagnosed 97% of women who actually had cervical cancer or dysplasia.

Dr Franco wrote an editorial to accompany The Lancet study, urging more clinical trials to get to the bottom of whether having HPV results would add value to the cytology. He's taken a leaf out of his own book, and is currently running a study in Montreal and St John's, Nfld to determine whether HPV testing should be standard.