Vulvar, vaginal precancer rates decreased after HPV vaccine was introduced
High-grade vulvar, vaginal and anal precancer rates decreased or stabilized after the introduction of the HPV vaccine, according to findings published in the American Journal of Preventive Medicine.
“HPV causes nearly all cervical cancers and a large proportion of vaginal, vulvar, and anal cancers,” Mona Saraiya, MD, MPH, a medical officer and team lead of the CDC’s Division of Cancer Prevention and Control’s Epidemiology and Applied Research Branch, and colleagues wrote.
Vaccine-type HPV infections, anogenital warts, cervical precancers and invasive cervical cancers have decreased in the U.S. since the introduction of the HPV vaccine to girls in 2006 and boys in 2011, they added.
Saraiya and colleagues examined the incidence rates of intraepithelial lesions grade 3 vulvar, vaginal and anal precancers among individuals aged 15 to 39 years. Using 2000 to 2017 data from select cancer registries, the data covered 27.8% of the U.S. population that required reporting of these precancers.
During the study period, there were a total of 6,128 vulvar, 945 vaginal and 462 anal precancer cases among females and 2,154 anal precancer cases among males. Following the introduction of the HPV vaccine, high-grade vulvar precancer rates declined by 21% per year after HPV vaccine introduction among females aged 15 to 19 years, 11.2% per year among women aged 20 to 24 years and 7.6% per year among women aged 25 to 29 years. Also, high-grade vaginal precancer rates declined by 19.1% per year among females aged 15 to 19 years and 5.6% per year among women aged 30 to 39 years, according to the researchers.
Prior to the vaccine introduction period, high-grade anal precancer rates were increasing. However, after the vaccine was introduced, anal precancer rates stabilized among females aged 15 to 29 years and among men aged 30 to 39 years, Saraiya and colleagues observed. However, among males aged 15 to 29 years, the anal precancer rates increased by 35% from 2000 to 2007 and increased by 7% from 2007 to 2017.
Most vulvar and vaginal precancer cases were detected among women aged 30 to 39 years (62.8% and 60.7%, respectively) and non-Hispanic white females (64.6% and 61.1%, respectively). Saraiya and colleagues also observed that most anal precancer cases were detected among women and men aged 30 to 39 years (77.9% and 77.1% respectively) and non-Hispanic white females and males (55.8% and 46%).
Decreases in vulvar and vaginal precancer rates “among younger age groups are analogous to decreases observed in cervical precancers, which have been attributed to the introduction of the HPV vaccine,” Saraiya and colleagues wrote.