Reacción a "Incidence of colon cancer continues to rise in young people in many high-income countries, although not in Spain"

The study uses the World Health Organization-IARC database “Cancer Incidence in Five Continents Plus”, which is a database where different registries from around the world participate. This makes the number of cases high, thus increasing the statistical power. 

The study presented on the latest trends in the incidence of colorectal cancer in young people shows an increase in incidence in some countries (in 17 countries out of the 50 studied).  

The methodology is correct. These studies are useful and necessary for long-term evaluation of chronic disease control.  

According to data on cancer estimates in Spain prepared by REDECAN, 60,000 cases of colorectal cancer will be diagnosed in Spain in 2024, being the most frequent tumor in men and women.  

According to the data of this study, Spain does not show an increase in the incidence of colorectal cancer in young people. 

The study seeks to investigate the incidence and trend of colorectal cancer incidence, comparing age groups and dividing countries into high, medium and low development regions. From these results, risk factors associated with the lifestyle of the countries could be hypothesized and their trends compared.  

The results of this study are in line with other recently published studies assessing mortality trends. 

These coauthors comment that while mortality from common cancers has generally declined over the past three decades, mortality from colorectal cancer has increased in some countries, highlighting the need to control the obesity epidemic and implement surveillance strategies targeting young populations.  

There are possible explanations for this increase in colorectal cancer incidence and mortality in young people. Risk factors that have undergone changes in recent decades and that may affect young people include mainly environmental factors, such as obesity in adolescence, prolonged sedentary behavior, and dietary factors that are now increasingly consumed during childhood and adolescence, such as sugary drinks, red and processed meats, and Western diets. 

Unfortunately, observational studies offer only a superficial view of our understanding of the biology of colorectal cancers in young people. Robust epidemiological studies with validated dietary and lifestyle data collected prospectively and repeated over a lifetime (the exposome) are crucial. These studies are vitally important to accurately measure exposures, their potential confounders, and the time and latency window of cancer related to the risk factors involved.  

In addition, observed incidence data are up to 2017 in most countries, these incidence trends will need to be monitored with more recent data.