Study Maps Gene and Environmental Links to Early Colorectal Cancer

<p>Background: To systematically appraise and synthesize avail-able epidemiologic evidence on the associations of environmental and genetic factors with the risk of sporadic early-onset colorectal cancer (EOCRC) and early-onset advanced colorectal adenoma (EOCRA).</p><p>Methods: Multiple databases were comprehensively searched to identify eligible observational studies. Genotype data from UK Biobank were incorporated to examine their associations with EOCRC in a nested case-control design. Meta-analyses of envi-ronmental risk factors were performed, and the strength of evidence was graded based on predefined criteria. Meta-analyses of genetic associations were conducted using the allelic, recessive, and dom-inant models, respectively.</p><p>Results: A total of 61 studies were included, reporting 120 environmental factors and 62 genetic variants. We found 12 risk factors (current overweight, overweight in adolescence, high waist circumference, smoking, alcohol, sugary beverages intake, seden-tary behavior, red meat intake, family history of colorectal cancer, hypertension, hyperlipidemia, and metabolic syndrome) and three protective factors (vitamin D, folate, and calcium intake) for EOCRC or EOCRA. No significant associations between the exam-ined genetic variants and EOCRC risk were observed.</p><p>Conclusions: Recent data indicate that the changing patterns of traditional colorectal cancer risk factors may explain the rising incidence of EOCRC. However, research on novel risk factors for EOCRC is limited; therefore, we cannot rule out the possibility of EOCRC having different risk factors than late-onset colorectal cancer (LOCRC).</p><p>Impact: The potential for the identified risk factors to enhance the identification of at-risk groups for personalized EOCRC screen-ing and prevention and for the prediction of EOCRC risk should be comprehensively addressed by future studies.</p>