|Background: Screening for cancer is a secondary prevention strategy that relies on early detection of disease. Screening is given to asymptomatic individuals who are at risk of developing cancer to identify and halt the pathological development of disease, reduce treatment invasiveness and improve outcomes. Perceived susceptibility (PS) – whether an individual feels they are personally vulnerable to a health-related condition or disease – has been shown to be associated with cancer screening uptake and past screening behaviour.
Overall Objective: We propose to use data from Alberta’s Tomorrow Project (ATP) to address the research questions outlined below.
Research Questions: Is PS to developing cancer associated with the incidence of mammography, prostate-specific antigen, sigmoidoscopy, and colonoscopy screening tests? Does an individual’s perceived susceptibility affect screening behaviour differently between tests?
Methods: We included ATP participants between the ages of 35 to 70 years who reported being free of chronic conditions at their baseline survey and who had completed at least one follow-up survey. PS was measured using three variables: PS1-5 (measured on a 5-point scale from 1 [low risk] to 5 [high risk]): “Compared to other people your age, what do you think are your chances of being diagnosed with cancer in your lifetime”, PS100gen asked: “On a scale of 0% to 100%, what percentage of people your age in the general population do you think will be diagnosed with cancer in their lifetime?” and PS100my asked: “On a scale from 0% to 100%, on which 0 means you definitely will not be diagnosed with cancer and 100 means you definitely will be diagnosed with cancer, what would you estimate to be your chance of being diagnosed with cancer in your lifetime?”. To examine the association between PS and incident screening over the course of follow-up, we built a series of multivariable logistic regression models for each of the screening tests of interest, and adjusted for covariates such as age, education, family history, and marital status.
Results: PS of developing cancer was statistically significantly associated with prostate-specific antigen (PSA) and sigmoidoscopy/colonoscopy screening behaviour over baseline and two waves of follow-up, spanning a total of 14 years, for both personal risk variables (PS1-5 and PS100my). Specifically, the odds of receiving compared to not receiving a PSA test were 1.36 times greater for a one-unit increase in PS1-5 (CI=1.07 – 1.72), and the odds were 1.02 times higher for a one-unit increase in PS100my ranging from 0 to 100 (CI=1.01 – 1.03). Furthermore, the odds of receiving compared to not receiving a sigmoidoscopy/colonoscopy were 1.97 times greater for a one-unit increase in PS1-5 (CI=1.52 – 2.55), and the odds were 1.03 times greater for a one-unit increase in PS100my ranging from 0 to 100 (CI=1.0 – 1.04).
Conclusion: Understanding how certain factors, such as PS, are associated with screening behaviour has been an important focus for addressing the underutilization of screening for cancer in Canada. Personal PS of developing cancer is predictive of screening behaviour for PSA and sigmoidoscopy/colonoscopy screening tests over time. These findings provide a basis for public health programming and policies throughout Canada, aimed at promoting screening behaviour. Future studies should explore additional factors, as outlined by existing social-cognitive models, such as perceived barriers to screening, to broaden the understanding these factors have in influencing behaviour and behaviour change.