HPV test better than Pap when screening for cervical cancer

HPV test is better than Pap smear at detecting precancerous cervical changes study says

HPV test is better than Pap smear at detecting precancerous cervical changes study says

This study selected a sample of women in British Columbia, placing 9,457 women in a control group to receive liquid-based cytology (LBC) testing and 9,552 in an intervention group to receive HPV testing. The HPV test identified significantly more precancerous lesions earlier, and four years after the women were initially screened, they received both an HPV test and a Pap test. If the guidelines change, and people over 30 switch to the HPV test, doctors will still most likely recommend that sexually active patients younger than 30 stick with the Pap smear.

The research came from doctors and scientists working on Canada's cervical screening programme, including researchers from the University of British Columbia, British Columbia Centre for Disease Control, Lower Mainland Laboratories, British Columbia Cancer and McGill University.

Numerous medical groups have said that before moving to HPV testing only, they needed to see clinical trial results - such as the kind provided by the new head-to-head study - to determine which test, over time, was better at detecting the precancerous changes. They also found that women with negative HPV test were more likely to not have cancer for the next four years, compared to the ones that had a negative Pap test. Quite often the smear test can be unpleasant for women, but luckily there is an easier way to screen for cervical cancer risk.

"Most cases of cervical cancer happen in women who have not been regularly screened, or who have been screened, but don't have access to appropriate treatment", she says. She explained that according to the new draft guideline from the U.S. Preventive Services Task Force, HPV test may soon replace the Pap test. But because the HPV test is more sensitive to these abnormal cells, it could result in more women with positive rates resulting in a need for more colposcopies and biopsies, something the authors say could have unintended harm and increases in health care costs.

They also cautioned that more work needs to be done to assess the economic consequences of changing the screening model.

The National Cancer Institute's Mark Schiffman, who has done extensive research on HPV, said the study confirmed that it's important to move from the Pap smear to the HPV test alone. "In fact, at the conclusion of the study, all HPV-negative women were tested with the Pap smear, which led to finding additional cases of pre-cancerous lesions".

In most provinces, Pap tests are recommended every three years. They recruited 19,000 women to agree to get either an HPV tests or a standard Pap test. This type of cancer is mostly caused by the human papillomavirus (HPV), in as much as 99% of all cases.

This trial showed that screening with HPV testing leads to earlier diagnosis of cervical pre-cancer and picks up cases that Pap testing missed, he said. The two groups were again tested with both the methods post of 4 years. Now, armed with the new study and previous ones, some experts say the Pap smear should be dropped.

"If you tested everyone for HPV in their twenties, they are nearly all going to be positive, but there's going to be all of this intervention that's not needed", she says.

The HPV test also seemed better at predicting who'd stay cancer-free, the investigators found. Women whose HPV test showed they didn't have the infection were less apt to develop a pre-cancerous lesion over the next four years, compared to women who'd gotten the Pap test alone.

The new study will probably "help push that along", said Wright of NewYork-Presbyterian/Columbia University Medical Center. From the participants, 9,552 women were screened using HPV test and those who were negative for the test came back after four years for a check if they had a pre-cancerous or cancerous lesion.

"It's really wonderful, there's no other test that gives us this level of reassurance for that period of time for a cancer", Harper says. He called use of the HPV test only a "reasonable strategy" but noted that the test's strength - its sensitivity - could result in more positive results and more testing.

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