Colorectal Cancer
More than 50% of colorectal cancer can be prevented by adopting healthy behaviors.
Colorectal cancer is the second leading cause of cancer death worldwide, with an estimated 1.9 million new cases and 900,000 deaths. Incidence rates range from <5 per 100,000 in Cape Verde, Sierra Leone, and India to >45 per 100,000 in Denmark and Norway (Map 16.1) and are strongly correlated with human development levels (Figure 16.1).
Colorectal cancer incidence rises with increasing levels of human development, driven by lifestyle and dietary patterns linked to economic growth.
Colorectal cancer incidence, age-standardized rate (world) per 100,000, by Human Development Index (HDI) and continent, 2022
Overall incidence rates are increasing in transitioning countries (Figure 16.2), coinciding with a rising prevalence of risk factors, such as consumption of red meat, processed meat, sedentary lifestyle, excess body fatness, smoking (in some countries), and alcohol intake. In contrast, rates have declined or stabilized in many high-income countries, such as the United States, United Kingdom, and New Zealand, because of changing patterns in risk factors (Figure 16.3), such as less smoking, and uptake of screening in recent decades. This progress, however, is confined to older adults in many countries, as colorectal cancer rates have been rising among adults aged <50 years in numerous high-income countries since around the mid-1990s (Figure 16.2).
The rising incidence of colorectal cancer among young adults in numerous countries is a bellwether for the future global disease burden across all adult age groups.
Trends in colorectal cancer incidence by age group, age-standardized rate (world) per 100,000, 1953-2017
20-49 years
50+ years
Studies of colorectal cancer incidence rates by birth cohort demonstrated that the risk of developing colorectal cancer is increasingly elevated among successive generations born since the 1950s. The reasons remain undetermined but may include increases in excess body weight and changes in diet.
Colorectal cancer risk factors and relative risk
Footnote
The risk of disease in people with a particular “exposure” compared to people without the exposure. For dietary factors the highest versus lowest consumption is compared. A value greater than 1 indicates higher risk with exposure, whereas less than 1 is a protective effect.
Colorectal cancer screening is associated with reduced incidence and mortality (Figure 16.4). However, whether to implement organized screening programs is dependent on both the disease magnitude and whether there are sufficient resources to provide adequate diagnostic follow-up and treatment services. Screening reaches only a small fraction of the target population worldwide, and even in countries where it is available, socioeconomic and regional disparities remain in screening uptake. Primary prevention represents an opportunity to mitigate the escalating global burden of colorectal cancer, including interventions that support individuals to quit smoking, abstain or reduce alcohol consumption, engage in regular exercise, and maintain a healthy diet and body weight.