Colorectal Cancer Risk and Protective Factors Among People of African Descent: A Systematic Review and Meta-Analysis

Abstract

Colorectal cancer (CRC) remains one of the leading causes of cancer-related morbidity and mortality worldwide, particularly affecting populations in low- and middle-income countries. Lower screening utilization among African descent has been linked to delayed diagnosis and early intervention. This review aims to identify the most common risk and protective factors of CRC among people of African descent. A comprehensive search was conducted on PubMed and Google Scholar databases from inception to the 21st of April 2025, and 5062 articles were synthesized. Of these, 30 articles were included for final qualitative analysis, data extraction, and meta-analysis. We included original peer-reviewed articles written in the English language that report CRC patients' possible risk or protective factors for CRC among adult patients of any gender and of African descent in any country around the world. Our review included 53,596 people of African descent across nine countries, and 8317 (16%) of them were diagnosed with CRC via colonoscopy and histology. The non-modifiable risk factors reported include: age > 55 years, family history of CRC, male gender, family history of malignancy, and genetic mutation, while the modifiable risk factors include: tobacco smoking, frequent consumption of alcohol, red/processed/roasted meat (suya), a fat diet, BMI > 30 kg/m², Helicobacter pylori infection, carcinogen exposure at work, and urban residence. Among the protective factors against CRC, frequent consumption of vegetables, fruits, fish, traditional African diet, nonsteroidal anti-inflammatory drug (NSAID) use, and physical activity were mostly reported. The pooled prevalence of CRC was 41.8% (95% CI: 39.6-44.1%), reflecting data primarily from hospital-based and high-risk populations, and not general population screening. Significant heterogeneity was observed (Cochran's Q > 1000, I² > 98%), indicating substantial variation among studies. Family history of malignancy, tobacco use, alcohol intake, obesity, and red or processed meat consumption emerged as the most consistently reported risk factors. Protective behaviors, such as high vegetable intake, physical activity, and adherence to traditional African diets, were underreported but suggest actionable avenues for prevention. The findings emphasize the urgent need for earlier and more culturally tailored screening interventions, as well as investment in molecular and registry-based research within African health systems.

Keywords: african; african american; african descent; colorectal cancer; protective factors; risk factors.

Figure 1. PRISMA flow diagram

A methodological flow diagram following the RRISMA guideline for systematic reviews PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses

Figure 2. Forest plot showing the individual and pooled prevalence estimates of colorectal cancer among populations of African descent across 35 studies

Horizontal lines represent 95% confidence intervals. The red vertical line indicates the pooled prevalence estimate derived using a random-effects model.