Association of Low Educational Attainment and Higher Colorectal Cancer Risk: Mediatory Effect of Lifestyle-Associated Factors Within Local Context.

Background: Educational attainment may influence colorectal cancer (CRC) risks, though the association remains inconclusive. The association might be mediated by health behaviors. This study aimed to explore the association of education on risks of CRC and to elucidate the mediatory effects of lifestyle-associated factors.

Methods: This case-control study included 174 cases and 296 healthy controls. We used a semi-structured questionnaire to collect information on participants' sociodemographic factors (age, sex, marital status, monthly income, and family history of CRC) and lifestyle-associated behaviors (smoking status, physical activity, and frequency of red meat, legumes, and vegetables intake). Body mass index (BMI) was calculated using body mass measured at first contact. Participants' education was categorized into those who completed basic education (≥ 12 years) and those who did not complete basic education (< 12 years). Logistic and multiple logistic regression analyses were employed to test the correlation between education and risk of CRC, adjusted by sociodemographic and lifestyle-associated factors. Path analysis was performed to test the mediatory effect of lifestyle-associated behaviors on the correlation.

Results: Participants with lower educational attainment had higher odds of CRC (odds ratio (OR) = 4.76, 95% confidence interval (CI) = 3.07 - 7.38), and the association remained consistent when adjusted by sociodemographic factors (adjusted OR (aOR) = 3.06, 95% CI = 1.86 - 5.03) and combined with lifestyle-associated behaviors (aOR = 2.73, 95% CI = 1.43 - 5.22). The association were consistent among men (OR = 6.14, 95% CI = 3.12 - 12.06; aOR = 4.65, 95% CI = 2.19 - 9.87; aOR = 1.05, 95% CI = 1.02 - 1.09), yet no longer significant among women when adjusted with sociodemographic and lifestyle-associated factors (OR = 3.91, 95% CI = 2.19 - 6.97; aOR = 2.02, 95% CI = 1.02 - 4.00; aOR = 1.56, 95% CI = 0.61 - 3.95). Path analysis showed that the association between educational attainment and risk of CRC was mediated by physical activity, BMI, and intake of red meat, legumes, and vegetables.

Conclusion: In our study, educational attainment was inversely correlated with the odds of CRC and might be mediated by physical activity, BMI, and intake of red meat, legumes, and vegetables. Taking other sociodemographic and lifestyle-associated factors into account, the association between lower educational attainment and higher odds of CRC was more substantial among men. These findings highlight the importance of promoting education and healthy lifestyle behaviors, particularly among men, as an essential part of targeted public health strategies in reducing burden of CRC.