HPV screening more accurate than Pap test

In collaboration with the Press Association

A large Canadian study has revealed that testing women for cervical cancer-causing strains of the human papillomavirus (HPV) is a more accurate method of detecting the disease than the current method, the Pap test.

Cervical cancer is the second most common cancer among women under the age of 35, and the majority of cases are caused by two strains of HPV, types 16 and 18.

Researchers at McGill University have now completed the first round of the Canadian Cervical Cancer Screening Trial involving 10,154 women between the ages of 30 and 69 who were enrolled between 2002 and 2005.

They found that the HPV test, which detects the DNA of certain strains of the virus, was able to accurately detect pre-cancerous lesions in 94.6 per cent of cases.

In contrast, the traditional Pap test, in which cervical cells are examined under a microscope for signs of abnormalities, was accurate in only 55.4 per cent of cases.

Commenting on the findings, which are published in the New England Journal of Medicine, lead researcher Dr Eduardo Franco, director of the university's Division of Cancer Epidemiology, said: "We already knew before conducting this study that the sensitivity of Pap left a lot to be desired. However, 55.4 per cent accuracy is only slightly above chance."

The researchers noted that the Pap test does produce slightly fewer false positive results - in which the test appears to detect abnormalities that turn out to be false alarms - than the HPV test.

However, Dr Franco pointed out: "A false positive may be very disturbing and psychologically distressing for the patient, but in the end, she's free of disease.

"False negatives are very serious business, however. The patient will be assured that she's negative, all the while a pre-cancer has a chance to become a cancer or her existing cancer has a chance to grow."

Dr Lesley Walker, Cancer Research UK's director of cancer information, said: "This type of research is very encouraging because it suggests that testing for HPV, the virus which causes the vast majority of cervical cancers, could improve the way we screen for the disease.

"The current method of screening involves looking for changes in the cells of the cervix before a cancer has developed. The new research suggests that by testing for HPV we might be able to spot the warning signs even earlier and this might mean that women could go for screening less often.

"We still need to do more research to find out whether a test for HPV could completely replace the current screening test. And because the HPV test is more expensive, we would also need to check that this method is cost-effective."