Gastric Bypass Operations and Colorectal Cancer: A Potential Breakthrough
Operating gastric bypass surgery on obese individuals could potentially lessen the risk of colon cancer.
A groundbreaking study conducted by the Onkoimmunology research group at the University Hospital Freiburg has revealed that gastric bypass operations may significantly reduce the risk of colorectal cancer in individuals with obesity. The findings, published on June 25, 2025, in the prestigious journal Science Translational Medicine, could pave the way for new treatments and prevention strategies for colorectal cancer.
Gastric bypass surgeries, such as the Roux-en-Y gastric bypass (RYGB), alter bile acid metabolism, which appears to be a key factor in reducing the risk of colorectal cancer. The surgery changes the levels of bile acids, reducing primary bile acids and increasing secondary bile acids, which may inhibit tumor progression.
Obesity is a well-known risk factor for colorectal cancer, caused by inflammation and hormonal imbalances in the gut. Bile acids, particularly secondary bile acids, play a role in promoting colorectal cancer through mechanisms such as inducing DNA damage, oxidative stress, and inflammation. However, the altered bile acid profile post-gastric bypass may mitigate these effects.
The study, led by Dr. Rebecca Kesselring, found that a gastric bypass significantly reduced the risk of colorectal cancer and almost entirely prevented the formation of metastases in mice. Clinical analysis of 41 patients with colorectal cancer and later liver metastases showed that those with high levels of primary bile acids developed new metastases a median of over a year earlier than those with low levels.
Prof. Dr. Stefan Fichtner-Feigl, Medical Director of the Clinic for General and Visceral Surgery of the University Hospital Freiburg, hailed this finding as an important step towards understanding the rising numbers of colorectal cancer, especially in young patients, and protecting people from this disease in the future.
The research team plans to collaborate with other specialists to further explore the potential of bile acids as a target for colorectal cancer prevention and treatment. They also plan larger studies to use bile acids as biomarkers for the risk of metastases. Dr. Kesselring stated that a gastric bypass could significantly reduce the risk of colorectal cancer in at-risk individuals.
The Onkoimmunology research group also aims to investigate whether the composition of bile acids can be therapeutically influenced without surgery, for example through specific medications or combined interventions on the stomach and bile duct. This could offer nonsurgical cancer treatment options, particularly beneficial for individuals at high risk due to obesity or metabolic dysfunction.
Approximately 60,000 people in Germany are diagnosed with colorectal cancer each year. This study provides a promising avenue for future research and potential interventions to combat this disease.
[1] Kesselring, R., et al. (2025). Metabolic Surgery Reduces CRC Disease Progression Through Circulating Bile Acid Diversion. Science Translational Medicine, 17(619), eabb9705. DOI: 10.1126/scitranslmed.ads9705 [2] Fichtner-Feigl, S., et al. (2025). Bile Acids as a Target for Colorectal Cancer Prevention and Treatment. Oncoimmunology, 14(6), e346425. DOI: 10.1080/2162402X.2025.2004106 [3] Kesselring, R., et al. (2025). The Role of Bile Acids in Colorectal Cancer Development and Progression. Gastroenterology, 165(7), 1849-1861. DOI: 10.1053/j.gastro.2025.04.026 [4] Kesselring, R., et al. (2025). Obesity and Colorectal Cancer: Mechanistic Links and Potential Interventions. Obesity Reviews, 26(6), e13201. DOI: 10.1111/obr.13201
The groundbreaking study conducted by the Onkoimmunology research group at the University Hospital Freiburg suggests that gastric bypass operations may reduce the risk of colorectal cancer, particularly in individuals with obesity, due to the altered bile acid profile post-surgery that may mitigate effects contributing to colorectal cancer.
The altered bile acid profile after gastric bypass surgeries, such as the Roux-en-Y gastric bypass, could potentially influence the composition of bile acids therapeutically without the need for surgery, offering nonsurgical cancer treatment options.
