Swiss researchers have recorded a steady increase in colorectal cancer incidence among people under 50. An analysis of nearly 100,000 cases over the past 40 years has shown that the disease is increasingly being detected in young patients, often at advanced stages.
The work was published in the European Journal of Cancer.
Colorectal cancer remains the third most common cancer in the world and the second leading cause of cancer-related deaths. According to the WHO, more than 1.9 million new cases and about 900,000 deaths were reported worldwide in 2022.
In Switzerland, approximately 4,500 new cases are diagnosed each year. Screening has helped reduce incidence among people over 50, but the trend has been the opposite for younger patients. Researchers studied 96,410 cases of colorectal cancer registered from 1980 to 2021. Tumors detected before the age of 50 accounted for 6.1% of all cases. In this age group, the incidence increased by about 0.5% per year, reaching nearly 7 cases per 100,000 person-years of observation.
In people aged 50–74, the rates, on the contrary, decreased: by 1.7% in men and by 2.8% in women. A particularly noticeable increase was observed in rectal tumors in both men and women, as well as in the right sections of the colon in young women. The authors believe that various biological or environmental mechanisms may be behind this.
The most concerning detail is the stage at which cancer is found. Almost 28% of patients under 50 already had metastases at the time of diagnosis. Among older patients, this figure was about 20%. The authors of the study urge not to dismiss symptoms as age-related. Signs that warrant investigation can include blood in the stool, prolonged abdominal pain, unexplained weight loss, and persistent changes in bowel habits. In some countries, including the United States, the recommended age for starting screening has already been lowered to 45. For those with a hereditary predisposition, screening is advised even earlier.
The exact reasons for the increase in incidence are still unknown. Among the possible factors, researchers cite changes in diet, rising obesity rates, lifestyle, and environmental influences on the gut microbiome.
The authors of the study emphasize that age no longer guarantees protection against colorectal cancer. Specialists urge greater attention to alarming symptoms and not to delay examinations, as early diagnosis significantly increases the chances of successful treatment.
