A recent analysis of the Centers for Disease Control and Prevention (CDC) WONDER database reveals a 333% increase in colorectal cancer incidence among 15- to 19-year-olds and a 185% increase among 20- to 24-year-olds.
have twice the risk of colorectal cancer (IRR 2.4) and, in particular, a fourfold increased risk (IRR 4.3) of rectal cancer. This makes colorectal cancer the leading cause of cancer death in men under 50 and the second leading cause in women under 50 in the United States.
Across all types of gastrointestinal tumours, younger patients often have more aggressive disease characteristics. Black, Hispanic, indigenous and Asian populations were disproportionately affected by these trends.
In addition, women under the age of 55 are particularly affected by pancreatic and stomach cancer. The incidence rate among women is rising almost twice as fast as among men, which could be explained by gender-specific risk factors or biological mechanisms.1,2
Most of these cancer cases occur sporadically; only 10–25% are attributable to genetic variants. What has changed since 1950? Obesity, Western nutrition (in particular, increased consumption of highly processed foods and sugar), non-alcoholic fatty liver disease, physical inactivity, smoking and alcohol are among the modifiable factors associated with the greatest increase in risk.1,2
There is a linear correlation between body mass index (BMI) and the risk of cancer in early adulthood: this increases by 20% with every 5 kg/m² increase in BMI. Obesity in childhood and adolescence appears to have even more serious effects in this regard.
As a by-product of the Western lifestyle, young people are also increasingly affected by metabolic disorders and fatty liver disease, which are associated with a significant increase in tumour risk even in people of normal weight (‘lean NAFLD’).1,2 Toxins from the environment and consumer products also play a critical role.
‘To systematically address these issues, a multi-omics approach is needed that considers epidemiological associations such as obesity and nutrition as well as signatures in the genome, epigenome, metabolome and gut microbiome,’ conclude the study authors.2