Replacing traditional smear tests used in cervical cancer screening with a new test that detects human papillomavirus (HPV) DNA may allow regular testing to stop earlier for some women, a study published in Lancet Oncology suggests.1
The NHS invites women in England aged 25 to 49 for cervical screening every three years and those aged 50 to 64 every five years using cervical cytology (smear test). The new HPV test is being rolled out and will be the primary test used by the end of 2019. While more expensive than the current test, the HPV test has been shown to detect a higher proportion of women with high grade precancerous lesions (cervical intraepithelial neoplasia grade 2+ cases) enabling them to be treated before they progress into cervical cancer.
Researchers developed a mathematical model to estimate the lifetime risk of cervical cancer in older women using Canadian healthcare data and the assumption that 42% of women who live until age 100 will have a total hysterectomy.
The model predicted that without cervical screening or vaccination against HPV, one in 45 women would be diagnosed with cervical cancer in their lifetime (95% percentile interval, 1 in 32 to 1 in 64). Perfect adherence to cytology screening every 3 years between the ages of 25 and 69 reduced the lifetime risk of cervical cancer to 1 in 532 in unvaccinated women (1 in 375 to 1 in 820).
For unvaccinated women with typical adherence to cytology screening (less than perfect adherence at screening intervals of longer than three years), stopping screening at age 55 was associated with a lifetime risk of cervical cancer of 1 in 138 (1 in 109 to 1 in 188), compared with 1 in 160 (1 in 127 to 1 in 213) when screening was stopped at 70 years. This indicates that a substantial part of the reduction in risk is from screening before age 55 years.
The model showed that the type of screening test used was important—women who had a negative HPV test at 55 had a much lower remaining lifetime risk of cervical cancer (1 in 1940) than those who had a negative cytology test at that age (1 in 440). In fact, women who stopped screening after a negative HPV test at age 55 years were predicted to have a lower remaining lifetime risk of cervical cancer (1 in 1940; 1 in 1271 to 1 in 3381) than women with the same typical screening adherence but who continued cytology screening up to age 70 years and then stopped after a negative cytology test (1 in 1206; 1 in 942 to 1 in 1748).
Researcher Talia Malagon, from the Division of Cancer Epidemiology at McGill University in Montreal, Canada, said: “Our results suggest that for countries that use HPV testing as part of their screening, it might be possible to stop screening earlier than we are currently doing, provided women have a negative HPV test.
“Our study did not include any cost effectiveness analysis, which will be a useful next step to inform policy decisions before any change in guidance is considered.”
The UK National Screening Committee will look at its cervical screening recommendation next year as part of its regular review process.
Anne Mackie, director of screening at Public Health England, said: “The UK’s independent expert screening committee looks forward to reviewing the findings of this new international research and will consider its results.”
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