Concerning colorectal cancer, its incidence has increased in all age groups in most countries, especially in those in epidemiological transition because of the change in risk factors related to westernized lifestyle. In some high-income countries, they observed a decrease in the incidence of colorectal cancer though.
This decrease may be partially explained by colorectal cancer screening at least in adults aged less than 75 years but also by change in risk factors. Indeed, in New Zealand there is no colorectal cancer screening program, and the incidence of colorectal cancer has decreased over the study period. Besides, a decrease in the incidence in adults aged 75+ not usually targeted by organized screening program also indicates a potential change in risk factors profiles.
Regarding prostate cancer, its incidence has increased in men aged less than 75 years old in most countries, and in those 75 years old mainly in Asia. It is hypothesized that the increase in Asia is explained by the westernization of lifestyle and prostate cancer screening.
The incidence of breast cancer was increasing in most countries but more importantly in Asian countries. In Northern American countries, European countries, and Australia, breast cancer incidence decreased in the 50-64 age group, reflecting the reduced use of hormonal replacement therapy since early 2000s.
Since 2012, a lot has changed in terms of prevention and cancer screening (i.e., PSA-based cancer screening), we hope that CI5 data will be soon updated so we can have an updated picture of the incidence trends. We will continue describing the cancer burden specifically in older adults, not only in terms of incidence but also in terms of number of years lost and survival. Stay tuned.