Background <p>Colorectal cancer is one of the most common tumor entities worldwide and ranks second in terms of tumor-related mortality. A&#xa0;worrying increase in colorectal cancer incidence has been observed in younger age groups in recent years. Furthermore, tumor immunotherapy, which has achieved spectacular success in various tumor entities, is still not a&#xa0;valid option for the majority of colorectal cancer patients. For these reasons, a&#xa0;deeper understanding of the mechanisms of colorectal cancer carcinogenesis is of great importance.</p> Objective <p>The aim of this article is to provide a&#xa0;brief overview of colorectal cancer with regard to its incidence, epidemiology, risk mechanisms, molecular genetic background, and therapeutic options. We further aim to provide an in-depth overview of the current discussion on the mechanisms of carcinogenesis, including new findings on the significance of altered lipid metabolism and genotoxic and tumorigenic substances such as colibactin which are produced by intestinal bacteria.</p> Materials and methods <p>A&#xa0;selective literature search was conducted in the PubMed database. Moreover, the authors’ own patient cohort from the Department of Surgery at the Technical University of Munich (TUM) was investigated.</p> Conclusion <p>In addition to well-established triggers such as chronic inflammatory bowel disease, direct and causal influences of the microbiome that can lead to genotoxic DNA damage have recently been discussed in the carcinogenesis of colorectal cancer. However, the increase in colorectal cancer cases among younger populations observed in many countries and the possible underlying mechanisms of carcinogenesis are still largely unknown.</p>