The Role of Probiotics in the Prevention and Complementary Treatment of Colorectal Cancer. Part 1

Colorectal cancer (CRC) is one of the most prevalent and lethal malignancies globally, with a concerning rise in incidence among younger populations. This article, the first of a two-part series, explores the pathophysiology of CRC, focusing on the adenoma-carcinoma sequence and the anatomical factors influencing disease progression. Central to this discussion is the human gut microbiota—a complex "new organ" essential for metabolic and immunological homeosta-sis. We examine how environmental factors, genetics, and lifestyle choices lead to dysbiosis, a microbial imbalance that fosters chronic inflammation and carcinogenesis. By reviewing the spatial distribution of bacterial phyla and the transition from a healthy to a pathogenic state, this paper establishes the microbiological foundation necessary to understand CRC development and the potential for targeted microbial interventions.