Assessing global transitions in human development and colorectal cancer incidence.

Colorectal cancer incidence has paralleled increases in human development across most countries. Yet, marked decreases in incidence are now observed in countries that have attained very high human development. Thus, in this study, we explored the relationship between human development and colorectal cancer incidence, and in particular assessed whether national transitions to very high human development are linked to temporal patterns in colorectal cancer incidence. For these analyses, we utilized the Human Development Index (HDI) and annual incidence data from regional and national cancer registries. Truncated (30-74 years) age-standardized incidence rates were calculated. Yearly incidence rate ratios and HDI ratios, before and after transitioning to very high human development, were also estimated. Among the 29 countries investigated, colorectal cancer incidence was observed to decrease after reaching the very high human development threshold for 12 countries; decreases were also observed in a further five countries, but the age-standardized incidence rates remained higher than that observed at the threshold. Such declines or stabilizations are likely due to colorectal cancer screening in some populations, as well as varying levels of exposure to protective factors. In summary, it appears that there is a threshold at which human development predicts a stabilization or decline in colorectal cancer incidence, though this pattern was not observed for all countries assessed. Future cancer planning must consider the increasing colorectal cancer burden expected in countries transitioning towards higher levels of human development, as well as possible declines in incidence among countries reaching the highest development level.