(Source: Medical News Today 2014-09-17）
A new study published in The BMJ claims that a simple urine test for human pappillomavirus - the main cause of cervical cancer - could increase screening uptake among women by offering them a non-invasive option.
The most common screening method for human papillomavirus (HPV) is a Papanicolaou (Pap) test, also known as a smear test. This involves a doctor or nurse scraping cells from the opening of a womans cervix, before sending them to a laboratory to be analyzed for abnormalities.
The American Cancer Society claim that between 1955 and 1992, death rates from cervical cancer fell by almost 70% due to increased Pap testing. But despite this success, screening uptake in recent years has been low.
Current screening recommendations from the US Preventive Services Task Force (UPSTF) state that women between the ages of 21 and 65 should have a Pap test every 3 years.
However, figures show the percentage of women following these recommendations stands at 83% - well below the target of 93%. In the UK, cervical screening rates have fallen below 80%.
According to the researchers of this latest study - including Dr. Neha Pathak of the Womens Health Research Unit at the Blizard Institute of Barts and the London School of Medicine and Dentistry in the UK - past studies have indicated that an alternative to Pap testing could be to test urine for signs of HPV. But they note the accuracy of such testing has been unclear.
Urine HPV testing should be an acceptable screening alternative
With this in mind, Dr. Pathak and colleagues set out to compare the accuracy of urine HPV testing against the collection of cervical samples.
To do this, they analyzed the results of 14 studies that looked at both forms of testing, involving a total of 1,443 women who were sexually active.
They found that on average, the sensitivity of urine HPV testing - the proportion of positive results correctly identified - was 87%, while specificity - the proportion of negative results correctly identified - stood at 94%, compared with collection of cervical samples. When using urine HPV testing to identify HPV types 16 and 18 - the primary causes of cervical cancer - sensitivity was 73% and specificity was 98%.
The team notes that accuracy of the urine HPV test increased when the first urine sample of the day, referred to as the “first-void,” was used.
Commenting on their findings, the researchers say: “Our review demonstrates the accuracy of detection of HPV in urine for the presence of cervical HPV. When cervical testing for HPV is sought, urine-based testing should be an acceptable alternative to increase coverage for subgroups that are hard to reach.”
Further studies warranted
They note, however, that their results should be “interpreted with caution” because of the variation found between individual studies, which could lead to overestimation or underestimation of results.
“The consequences of overestimation are especially important as they can lead to unacceptable morbidity and mortality,” say the researchers. “False negative results would lead to missing cases of precancerous or cancerous lesions, and false positive results would lead to overinvestigation and anxiety. Both scenarios could easily result in a lack of trust in HPV testing.”
The team believes more studies are warranted to further investigate the accuracy on urine HPV testing, and to look at the feasibility and costs of this method in a clinical setting.
In an editorial linked to the study, Harry C. Kitchener and Gemma L. Owens, of the University of Manchester in the UK, say urine HPV testing could be an achievable and beneficial alternative to HPV testing of cervical samples.
“In well-resourced health systems, self-sampling could be used for women who are reluctant to attend for regular cervical screening,” they note. “In lower income countries that lack infrastructure, self-sampling might even be beneficial and cost-effective for all women who are eligible for screening. More research is now required to identify the true clinical performance and acceptability of urine testing for HPV in both settings.”
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