Effectiveness of organized cervical cancer screening has been shown in several studies. However, screening under 25 years old women has been shown to have little or no impact on the risk of cervical cancer and clear effects have been observed above 40 years. In Finland an extensive opportunistic screening practice that concentrates especially on younger women exits alongside the national screening programme. However, the significance of the opportunistic testing in preventing cervical cancer is unclear. The aim of this study is to clarify the effect of opportunistic testing and organized screening on the risk of cervical cancer among young women in Finland.
There were 462 cervical cancer cases screened and diagnosed among women aged below 40 years and in 2000-2009 in the Finnish Cancer Registry. Screening histories for these women and their 2,772 age-matched controls were derived by linkage to the mass screening register. The data was further linked with opportunistic testing data available for 29% of the cases and 34% of the controls. The opportunistic data includes Pap smears taken in the public primary health care covering the southern parts of Finland (Turku and Uusimaa region), Pap smears taken in the student health care and Pap smears reimbursed in the private sector covering the whole country. OR’s and 95% confidence intervals for the association of cervical cancer diagnosis and participation in organized screening and opportunistic testing 0,5-5,5 years before the diagnosis were estimated using unconditional logistic regression. The results were not yet corrected for self-selection bias.
OR of cervical cancer for screening below age 25 was 0.93 (95% CI 0.31-2.81). All smears in that age group were from opportunistic testing. Participation in organized screening at 25 to 40 resulted in OR 0.52 (0.36-0.75), participation only in opportunistic testing 0.75 (0.49-1.14) and participation in both organized screening and opportunistic testing 0.44 (0.24-0.81).
According to initial results opportunistic testing showed no clear additional benefit on preventing cervical cancer. The study also supports previous findings about the lower effect of screening in younger age groups compared to older ones. Taking into account the high costs of screening and related CIN treatments in young women, current screening practice in Finland should be questioned and revised.