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

Colorectal cancer (CRC) is the third most common type of cancer worldwide (more than 1.9 million cases were diagnosed in 2022) and is the second most common cause of cancer death (causing more than 900,000 deaths per year), despite the existence of effective screening techniques that could reduce the number of deaths from this disease. Monitoring the situation of this cancer is therefore crucial to be able to control the impact of this disease on the population.  

Previous studies had already observed that the incidence of this cancer was increasing among young adults (<50 years) in several high-income countries (USA, Canada, Australia...) (1%-4% per year), and that it showed heterogeneous trends in Europe. The work of Hyuna Sung, et al., which is a well-prepared study, presents a more up-to-date view in many cases and contemplates a wide range of regions of the world, which makes it easier to compare different types of situations and to generate hypotheses on the causes that may be explaining the observed trends.  

In this regard, CRC in young adults is partly due to hereditary cancer syndromes, but most cases are sporadic. The possible reasons for the increases in incidence seen in this group, which could be related to the increasing prevalence of obesity, lack of exercise, and dietary factors such as alcohol and processed meat, are currently unknown. In addition, given that urbanization and pollution have also been associated with the overall increase in incidence, these factors could be playing some role in the trends in young adults. Studying the epidemiology of CRC may have many practical implications, such as establishing the age of screening initiation. In this regard, the U.S. findings supported the American Cancer Society in recommending initiation of screening at 45 years of age.  

Despite the limitations highlighted by the authors, such as the under-representation of developing countries or the lack of national coverage in the incidence data of some countries (as in Spain), and the fact that the period of time analyzed does not allow us to obtain a completely updated view of the situation, the study represents a great integrative effort that allows us, on the one hand, to obtain a good overview of both the situation of the evolution of colorectal cancer in young adults, and the possibility of identifying in which regions a greater effort is required in the collection of information.  

In Spain there is no increase in the incidence of CRC in young adults. This finding, which is not novel, could be explained by the lack of exposure to the factors already discussed. It should be noted that both the Spanish Network of Cancer Registries (REDECAN) and the Ministry of Health, together with the autonomous communities and the National Epidemiology Center (ISCIII) carry out activities to obtain reliable, updated and quality information to monitor the incidence of cancer in young adults. In addition, the Spanish Society of Epidemiology has also echoed the importance of the study of cancer in this group, setting up a spontaneous round table at this year's congress with the title “Epidemiología del cáncer en población adulta joven/Epidemiologia do cancro na população adulta joven” (Epidemiology of cancer in young adults/Epidemiology of cancer in young adults).