Colorectal cancer is a leading cause of cancer mortality worldwide and it is estimated that up to 75% of cases can be linked to modifiable risk factors, such as poor diet quality, alcohol consumption, and smoking. As part of the 2019 Global Burden of Disease study, a systematic analysis of data from 204 countries (1990-2019) estimated the incidence, mortality, and disability-adjusted life years (DALYs) linked to colorectal cancer. Globally, the main contributors to colorectal cancer DALYs were a diet low in milk (15.6%), smoking (13.3%), and a diet low in calcium (12.9%).
Globally, colorectal cancer is the third leading cause of cancer deaths and the second leading cause of cancer-related disability-adjusted life years (DALYs). It is estimated that 70-75% of colorectal cancer cases are linked to modifiable risk factors, such as smoking, alcohol consumption, sedentary behaviour, and a diet high in processed meats and low in fruit and vegetables. In the context of the 2019 Global Burden of Disease study, a systematic analysis of data from 204 countries estimated the incidence, mortality, and DALYs linked to colorectal cancer between 1990 and 2019, with additional considerations for age, sex, and geographical location.
Between 1990 and 2019, the worldwide incidence of colorectal cancer more than doubled, with annual cases rising from 824,098 to 2.17 million during this period. Both colorectal cancer mortality and DALYs followed similar trends, with 2019 rates being approximately twofold those of 1990. After results were standardised for age, the incidence of colorectal cancer in 2019 remained greater than that of 1990 (22.2 vs 26.7 per 100,000 person-years). Increases were higher in countries with a lower sociodemographic index (a measure of sociodemographic development). Researchers speculated that this may be partly attributable to lifestyle shifts and improved screening accessibility in the context of rapid economic growth. In countries with a high sociodemographic index, the age-standardised incidence and death rates generally remained similar or decreased, although increases in new cases and age-specific rates were observed in younger individuals (20-49 years).
DALYs, which consider both years of life lost and years lived with a related disability, estimate the years of healthy life lost. Overall, males had a higher incidence colorectal cancer as well as related deaths and DALYs than women. At the global level, the main contributors to colorectal cancer DALYs were a diet low in milk (15.6%), smoking (13.3%), a diet low in calcium (12.9%), and alcohol use (9.9%). The severity of risk factors varied by sex and geographic region. For example, globally, alcohol use accounted for 13.9% in men but only 4.5% in women. Conversely, DALYs caused by a diet low in milk or a diet low in calcium were similar between men and women (15.8 vs 15.5% and 13.6 vs 12.0%, respectively). Geographically, diets low in milk or low in calcium were the two highest DALY contributors in Sub Saharan Africa and Asian, with the exclusion of high-income Asian Pacific. In North America, a diet low in milk accounted for 8.8% of DALYs, while smoking was the highest DALY contributor (15.5%).
This study highlights the relevance of targeting modifiable risk factors in colorectal cancer prevention. From a global perspective, strategies such as dietary and lifestyle modifications, early screening among high-risk individuals, and improved treatment options will be key in achieving an overall reduction in colorectal cancer incidence, deaths, and DALYs.