Emerging trends in early-onset gastrointestinal cancers - a comparative review with late-onset cancers

INTRODUCTION: Early-onset gastrointestinal (GI) cancers, defined as those diagnosed before the age of 50, are increasing worldwide, whereas the incidence of late-onset GI cancers has stabilized or declined. These trends highlight the need to better understand age-related differences in disease biology and risk factors. METHODS: This narrative review compares early- and late-onset GI malignancies. We discuss differences in epidemiology, molecular and genetic features, clinical presentation, and management strategies. Relevant literature was identified through a non-systematic search of PubMed and additional sources, and selected according to scientific relevance and quality. Publications from 2000 to March 2026 were reviewed, with inclusion of selected landmark historical studies when appropriate. RESULTS: Early-onset tumors are more frequently diagnosed at advanced stages and may reflect the impact of early-life environmental exposures, metabolic dysregulation, and microbiome alterations. Although they share several molecular features with late-onset disease, younger patients often present distinct clinical and survivorship needs, including genetic counseling and fertility preservation. Current treatment strategies remain largely similar across age groups due to limited age-specific evidence. CONCLUSION: Early-onset GI cancers should be understood within an age-specific biological and environmental framework. Improved understanding of these tumors may support better prevention, earlier diagnosis, and more personalized management strategies.