High grade cervical lesions decline in young US womenBMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h3341 (Published 22 June 2015) Cite this as: BMJ 2015;350:h3341
The incidence of high grade cervical lesions in young women in the United States has fallen, a new analysis has found. The researchers reported in the journal Cancer that this may be caused by the introduction of the human papillomavirus (HPV) vaccine but may also be due to changes in screening guidelines.1
From 2008 to 2012, 9119 cases of high grade cervical lesions (CIN2+) were reported among 18 to 39 year olds as part of a sentinel system for the US Centers for Disease Control and Prevention.
In all four catchment areas the researchers found a dramatic and consistent decrease in the incidence of high grade lesions among women aged 18 to 20 over the study period. In California the incidence fell from 94 in 100 000 to 5 in 100 000; in Connecticut it fell from 450 to 57 in 100 000; in New York it fell from 299 to 43 in 100 000; and in Oregon it fell from 202 to 37 in 100 000. Among 21 to 29 year olds the rate of high grade lesions declined in Connecticut and New York but not in the other two areas. No change was seen among 30 to 39 year olds.
Vaccination against HPV has been available in the US since 2006. It is offered to girls aged 9 to 12 and as part of short term catch-up scheme targeting 13 to 26 year olds. The picture is unclear, however, as the recommended age for initiating cervical cancer screening was raised to 21 years during the same period, and screening intervals have been extended.
The researchers found that screening rates declined during the study period: the largest decreases were seen among 18 to 20 year olds (ranging from a 67% fall in Oregon to 88% in California), and smaller declines were recorded among 21 to 29 year olds (13% to 27%) and 30 to 39 year olds (3% to 21%).
Susan Hariri, study author, said that the decline in incidence of high grade lesions among 18 to 20 year olds was probably due to the widespread implementation of guidelines to start screening at age 21, but she added that the larger decreases in CIN2+ incidence may be an effect of the vaccine. In the 20 to 29 age group the trend was more difficult to interpret; Hariri said that the effect of the vaccine should become clearer over time as more women in this age group receive HPV vaccine at younger ages.
One limitation of the study was that vaccination status was available for only 47.5% of the women who would have been eligible during the analysis period. Also, patients needed to have received only one of the three recommended doses to be considered vaccinated.
In an accompanying editorial Harinder Brar and Allan Covens, from the University of Toronto in Canada, wrote that the study was notable because it was the first to look at incidence trends of high grade cervical lesions in the post-vaccination era in the US. But they added, “The inability to ascertain the overall vaccine uptake rate in the study population and the absence of a central cancer screening and vaccine registry, combined with the presence of considerable heterogeneity within the vaccinated group, make it difficult to draw any meaningful conclusions about how much of the decrease in CIN2+ can be attributed to vaccination alone.”
Cite this as: BMJ 2015;350:h3341