Trends of colorectal cancer incidence by education and socioeconomic status in Finland

Background: The aim of this study was to investigate if the incidence of colorectal cancer (CRC) is associated with education and socioeconomic status (SES) in Finland, and if there are any changes in incidence differences between the groups over the period 1976-2014.Material and methods: CRC cases (N = 77,614) were retrieved from the Finnish Cancer Registry and linked with information on the education level and SES from Statistics Finland. We used Poisson regression model to quantify differences in incidence rates between the groups, and to assess changes over calendar time.Results and conclusions: Colon cancer incidence was higher among the highly educated, than in those with basic education. Similar differences were observed by SES in men. Incidence rates increased steeply over time among men with basic education (from 16.7/100,000 in 1976-1979 to 31.8 in 2010-2014), resulting in narrowed differences between the groups (p < .001). Incidence trends of proximal and distal colon and rectal cancer in men showed similar patterns. Heterogeneity across time periods by SES was observed only in colon cancer incidence in men (p = .009). No such large differences were detected in women. Steep increase in colon cancer incidence in men with basic education, and the respective persistent high incidence in the highly educated highlights the importance of focusing the preventive measures on modifiable lifestyle factors in order to reduce CRC incidence and to narrow the educational and socioeconomic health differences.