February 27, 2014 — Summary of "Embracing a New Era in Cervical Cancer Screening," Isidean/Franco, The Lancet, Feb. 8, 2014.
Although human papillomavirus DNA testing is superior to the conventional cytology-based Pap test for detecting precursors to cervical cancer, findings from randomized controlled trials are needed "to show that HPV testing is more efficacious than cytology-based testing for prevention of subsequent invasive cervical cancer and related death," according to a commentary by Sandra Isidean of McGill University's Department of Epidemiology, Biostatistics, and Occupational Health, and Eduardo Franco of the university's Department of Oncology.
They discuss a new study in the same issue of The Lancet that analyzed data from such trials.
Isidean and Franco cite a study by Guglielmo Ronco and colleagues that pooled data from four European randomized controlled trials involving more than 175,000 women who received HPV-based or cytology-based cervical cancer screening.
The study found that "HPV-based screening resulted in a 60-70% reduction in invasive cervical cancer incidence, compared with cytology-based screening," according to Isidean and Franco. Although the reduction in incidence was not significant 2.5 years after screening, it was "decisive with longer follow-up," they write.
They note that "the most important property of HPV-based screening is the safety it brings to most women who have a negative HPV test." The study found the "cumulative incidence of invasive cervical cancer was lower 5.5 years after a negative HPV test than 3.5 years after a negative cytology test," which shows that HPV-based screening every five years is "safer" than cytology-based screening every three years, Isidean and Franco write.
Isidean and Franco predict that cervical cancer screening in high-resource settings "will most probably incorporate primary HPV testing," which "particularly befits the post-HPV vaccination era."
Because of economies of scale, potential competition among HPV test makers and longer screening intervals, "cervical cancer screening might end up costing countries less money while providing greater safety than with conventional cervical cytology," they add.
However, countries "need to consider important logistical challenges," such as deciding which HPV screening test to use, determining screening ages and intervals, developing protocols for HPV-positive women and "ensuring quality of and adherence to revised policies," they conclude.