How Ancestry and Genetic Variants Influence Colorectal Cancer Risk

Recent research highlights the significant role of genetic background and specific genetic variations in determining an individual's likelihood of developing colorectal cancer. A comprehensive Brazilian study, conducted by researchers at Hospital de Amor and other institutions, analyzed the impact of hereditary and non-hereditary genetic factors in a highly mixed population. The study, published in JCO Global Oncology, examined 45 genetic polymorphisms previously linked to colorectal cancer, aiming to assess their relevance within the diverse Brazilian demographic.

Using a sample of nearly 2,000 people—comprising both patients and healthy controls—the team genotyped these variants and evaluated participants' genetic ancestries, including proportions of European, African, Asian, and Indigenous heritage. Unlike subjective skin color assessments, they employed precise genetic markers to determine ancestry proportions.

The investigation identified nine variants significantly associated with colorectal cancer risk. Among these, four maintained independent significance after adjusting for clinical and environmental factors. Two variants increased risk, while two others appeared protective. These variants influence pathways related to inflammation and cell growth, indicating that common genetic differences, not just somatic mutations, contribute to disease susceptibility.

An additional key finding was the relationship between genetic ancestry and disease risk. The study revealed that individuals with higher proportions of African or Asian ancestry had a lower incidence of colorectal cancer. This pattern, consistent with international research, suggests that inherited genetic components from these populations may offer protective effects. The findings also imply that socioeconomic and lifestyle factors intertwined with ethnicity could influence risk, as dietary habits vary among different ancestral backgrounds.

The researchers emphasize that their large, representative sample provides robust evidence that genetic background significantly impacts colorectal cancer risk in Brazil’s diverse population. Although these genetic variants are unchangeable, understanding their influence could enable personalized screening and prevention strategies. For instance, individuals carrying risk-associated variants might benefit from more targeted screening or lifestyle modifications.

Looking ahead, the team plans to conduct further research mapping millions of genetic variants to develop a tailored genetic risk score for the Brazilian population. Such efforts could revolutionize early detection and intervention, ultimately reducing disease burden. This study underscores the importance of considering Brazil's unique genetic diversity in medical research, offering insights applicable to other diverse populations worldwide.

Source: https://medicalxpress.com/news/2025-09-ancestry-genetic-variants-colorectal-cancer.html