Effect of Test History at Ages 50-64 on Later Cervical Cancer Risk: A Population-based Case-control Study

As life expectancy increases, the effectiveness of cervical cancer screening programs needs to be reassessed for the older population. We addressed the effect of test history in and outside organized screening at age 50-64 years on later cervical cancer risk. A case-control study was conducted by deriving 229 cases of 65-79 years old women with invasive cervical cancer in 2010-2019 from the Finnish Cancer Registry. Ten controls were matched for each case by birth year and hospital district. The effect of test uptake and abnormal results in 50-64 year olds on cancer risk was investigated using conditional logistic regression and adjusted for self-selection. Test uptake within the 50-64 years age group showed 75% lower odds of cervical cancer [adjusted OR (aOR) = 0.25; 95% confidence interval (95% CI), 0.18-0.35]. Untested women had 4.9 times higher odds than those tested with normal results (aOR = 4.86; 95% CI, 3.42-6.92). Having at least one abnormal test result increased the odds by 2.5 when compared with only normal results but showed lower odds when compared with untested women. The importance of testing is exhibited by the result showing a reduction of odds of cancer to one-fourth for those tested compared with untested. Similarly, receiving abnormal results was protective of cancer compared with having no tests highlighting the importance of proper follow-up. Therefore, screening history should be considered when further developing cervical cancer screening programs with special interest in non-attenders and those receiving abnormal results at older ages.Significance: To our knowledge, this is the first study from Finnish data describing the effect of test history on later cervical cancer at older ages. Focusing on the cervical tests taken within the Finnish national screening program and outside it highlights the overall importance of having cervical tests and adds this study into the slowly increasing number of studies considering all cervical testing in Finland.