Early-onset colorectal cancer (EOCRC), defined as colorectal cancer diagnosed before age 50, represents an urgent and growing public health concern worldwide. Traditional screening often fails to detect EOCRC early, underscoring the need to identify modifiable risk factors and implement proactive prevention strategies. A structured literature review was performed using PubMed to evaluate studies on EOCRC epidemiology, risk factors, and disease mechanisms. Of 245 articles screened, 25 met inclusion criteria based on relevance, methodological quality, and recency. Data were extracted and synthesized regarding lifestyle, metabolic, inflammatory, environmental, and genetic contributors to EOCRC. Modifiable lifestyle factors, including obesity, Western dietary patterns, alcohol use, smoking, and sedentary behavior, consistently correlated with elevated EOCRC risk. Metabolic syndrome and chronic low-grade inflammation further promote early tumorigenesis. Chronic inflammatory gastrointestinal conditions, like inflammatory bowel disease, were associated with earlier disease onset. Emerging evidence implicates gut microbiome dysbiosis, bacterial toxin production, and environmental exposures as additional contributors. At the molecular level, dysregulation of signaling pathways such as WNT/β-catenin may link environmental and metabolic factors to early neoplastic transformation. While hereditary syndromes such as Lynch syndrome, mismatch repair gene mutations, and NTHL1 variants account for a minority of cases, most EOCRC arises sporadically, highlighting the growing impact of modifiable factors. The rapid rise of EOCRC demonstrates that age-based screening alone is insufficient. Integrating lifestyle, metabolic, inflammatory, environmental, and molecular risk factors into comprehensive, risk-stratified detection and prevention strategies is essential to enable earlier diagnosis, improve patient outcomes, and reduce morbidity and mortality in younger populations globally.
