With the first birth-cohorts of vaccinated women reaching the age of screening its characteristics (most notable positive predictive value) will change abruptly. There is a great need to redesign an appropriate screening protocol as right tools for the future cervical cancer screening programs. We report here the baseline characteristics and safety interim results of a randomized trial assessing the impact of infrequent vs. frequent cervical screening in human papillomavirus (HPV) type 16/18 vaccinated women.
Total female 1992-94 birth-cohorts (30129) were invited to and respectively vaccinated (9482 + 2036) as early adolescents (age 12-15 years) or as young adults (age 18 years) against HPV16/18 in a community-randomized trial (EUDraCT 2007-001731-55). Women in this trial will be screened at the age of 22, 25 and 30 years for cytological screening. In one arm, representing frequent screening, the participants receive information on all the cytological findings on each visit, in the other arm, representing infrequent screening, the participants receive this information only at the of 30, information on high-grade squamous intraepithelial lesion (HSIL)s is, however, given due to ethical reasons. In 2010-13, 4660 (49.1%) and 2036 (100%) of the HPV vaccinated women attended a baseline cervical screening visit, and in 2014-2017 4018 (42.4%) and 1326 (65.1%) of these women attended the 1st round of cervical screening at the age of 22 years.
Overall prevalence of HSIL and any abnormal cytological findings at the 1st screening round were: 0.3% (n=11) and 5.7% (n=220) in those vaccinated as early adolescents, and 0.2% (n=3), and 4.6% (n=58) in those vaccinated as young adults, respectively. The incidence rate from the 1st screening round of HPV16/18 and other HPV DNA are being currently analysed and will be combined with the above cytological results. Our previous results from the adolescent group at the age 18 showed HPV16/18 and HPV31/33/35/45 prevalence range from 9.9% to 10.7% and 9.2% to 10.2%, respectively.
Our birth cohorts attending screening, as described above, are in close to ten years ahead of comparable observational studies or monitoring of vaccination program participating birth cohorts in other affluent countries. Our study will show the first results of safety, accuracy and effectiveness of infrequent vs. frequent screening for cervical cancer safety which can pave the way to the future synergistic vaccination/screening programs.