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BACKGROUND: The association between socioeconomic position and incidence of colorectal cancer is inconsistent and differs by global region. We aimed to clarify this association in the Swedish population.

METHODS: We conducted a population-based open cohort study using data from Swedish national registers. We included all individuals, aged ≥30 years, residing in Sweden between 1993 and 2010. Socioeconomic position was indicated by (1) highest educational level (five groups), and (2) disposable income (quintiles). We used Poisson regression to estimate incidence rate ratios (IRR) and 95% confidence intervals (95% CI) of colon and rectal cancer, and colon and rectal dysplasia.

RESULTS: In total, 97,827,817 person-years were accumulated and 82,686 cases of colorectal cancer were diagnosed. Compared to men with 'higher secondary' education, the adjusted IRRs (95% CI) of rectal cancer in men with 'primary or less', 'lower secondary', 'lower university' or 'higher university' education were: 1.06 (1.00, 1.11), 1.05 (0.99, 1.10), 0.96 (0.89, 1.03), and 0.92 (0.86, 0.98), respectively. In women, the corresponding figures were: 1.04 (0.95, 1.14), 1.03 (0.94, 1.13), 0.92 (0.82, 1.02) and 0.92 (0.82, 1.02). Disposable income was not associated with rectal cancer incidence. Adjusted IRRs of colon cancer did not differ between levels of education or disposable income overall or for specific colon sub-sites. Neither education nor disposable income was consistently associated with incidence of colon or rectal dysplasia.

CONCLUSIONS: Prevention strategies for colon cancer should be applicable to individuals regardless of their socioeconomic position. However, factors conferred by education, e.g., health awareness, may be important for approaches aiming to reduce inequalities in incidence of rectal cancer. Further evaluation of cancer prevention and health promotion strategies among less educated groups is warranted.