© Fotolia

A new study has found that obesity, particularly during adolescence, significantly increases the risk of developing colorectal cancer. The researchers explain why the disease is being diagnosed increasingly often in people under the age of 50.

"The rising incidence of colorectal cancer among young adults is a trend that must be taken very seriously. Our analysis of international studies identified metabolic disorders—particularly obesity, type 2 diabetes, and dyslipidemia—as some of the key risk factors," says Prof. Dr. Gabriel Seifert, Senior Physician in the Department of General and Visceral Surgery and Head of the Colorectal Cancer Center at the Medical Center – University of Freiburg.

The findings are based on a meta-analysis led by Prof. Seifert in Freiburg, which pooled data from studies involving more than 117,000 patients. The results were published in the European Journal of Epidemiology.

Obesity emerges as the strongest risk factor

The strongest association identified in the analysis was between obesity and the development of colorectal cancer before the age of 50.

According to the study, individuals with obesity have an approximately 45% higher risk of developing colorectal cancer before age 50 compared with people of normal weight. Obesity during adolescence and early adulthood appears to be particularly important, with several studies linking excess weight at a young age to a substantially increased risk later in life.

Researchers also found an association between type 2 diabetes and an elevated risk of colorectal cancer among men aged 20 to 49. In some studies, the risk observed in these patients was comparable to that typically seen only after the age of 50.

Elevated blood lipid levels and arterial hypertension may also contribute to the risk, particularly when both conditions are present simultaneously.

Why early detection of metabolic disorders matters

According to Prof. Dr. Stefan Fichtner-Feigl, Head of the Department of General and Visceral Surgery at the Medical Center – University of Freiburg, the findings highlight the importance of identifying and treating metabolic disorders at an early stage.

“Preventing and treating obesity, diabetes, and other metabolic disorders should become an integral part of both colorectal cancer prevention and cancer care,” he emphasizes.

For patients diagnosed with both colorectal cancer and obesity, the Comprehensive Cancer Center Freiburg (CCCF) has established a specialized multidisciplinary team. Patients receive coordinated care addressing both the cancer and the underlying metabolic disease—from preoperative preparation through long-term follow-up.

Colonoscopy remains the most effective preventive tool

“Screening examinations are of enormous importance. Colonoscopy, in particular, allows precancerous lesions to be detected and removed before cancer develops,” says Prof. Dr. Robert Thimme, Head of the Department of Gastroenterology and Hepatology at the Medical Center – University of Freiburg.

At the same time, treatment strategies continue to evolve. Advances in molecular diagnostics are enabling physicians to increasingly tailor therapies to the individual characteristics of each patient's tumor.

One of the most promising developments is the analysis of circulating tumor DNA (ctDNA) in blood samples. In the future, this approach could help detect cancer recurrence earlier and provide a more accurate assessment of treatment effectiveness.

Researchers are also investigating the role of structured physical activity programs during and after cancer treatment. Regular exercise is believed to improve recovery and may reduce the risk of death following colorectal cancer.