Long-term trends in colorectal cancer: incidence, localization, and presentation

Abstract

Background: The purpose of this study was to assess trends in incidence and presentation of colorectal cancer (CRC) over a period of 37 years in a stable population in Mid-Norway. Secondarily, we wanted to predict the future burden of CRC in the same catchment area.

Methods: All 2268 patients diagnosed with CRC at Levanger Hospital between 1980 and 2016 were included in this study. We used Poisson regression to calculate the incidence rate ratio (IRR) and analyse factors associated with incidence.

Results: The incidence of CRC increased from 43/100,000 person-years during 1980-1984 to 84/100,000 person-years during 2012-2016. Unadjusted IRR increased by 1.8% per year, corresponding to an overall increase in incidence of 94.5%. Changes in population (ageing and sex distribution) contributed to 28% of this increase, whereas 72% must be attributed to primary preventable factors associated with lifestyle. Compared with the last observational period, we predict a further 40% increase by 2030, and a 70% increase by 2040. Acute colorectal obstruction was associated with tumours in the left flexure and descending colon. Spontaneous colorectal perforation was associated with tumours in the descending colon, caecum, and sigmoid colon. The incidence of obstruction remained stable, while the incidence of perforation decreased throughout the observational period. The proportion of earlier stages at diagnosis increased significantly in recent decades.

Conclusion: CRC incidence increased substantially from 1980 to 2016, mainly due to primary preventable factors. The incidence will continue to increase during the next two decades, mainly due to further ageing of the population.

Keywords: Colorectal cancer; Epidemiology; Incidence; Presentation; Trends.

Fig. 1

Population in Levanger Hospital’s catchment area in 1980 and in 2016, categorized by age groups

Fig. 2

Population in Levanger Hospital’s catchment area in 2018 and estimated population in 2040

Fig. 3

Number of new cases per 5-year period for both sexes and age groups. The two columns to the very left represent a 2-year period

Fig. 4

a Number of new cases with colorectal cancer during a 37-year period (left). b Number of new cases per 10,000 person-years (right)

Fig. 5

Effects of calendar year and age on the number of patients presenting with colorectal cancer. Effects of calendar year and age on the number of patients presenting with colorectal cancer in a Poisson regression with fractional polynomials (confidence intervals are shaded grey, logarithmic scale on the y-axis, males in the figures to the left). The increase for each calendar year diminished in the later years. The effect of age was linear in both males and females

Fig. 6

Estimated numbers of new cases with CRC by 2030 and 2040