With most colorectal cancer patients in Nigeria diagnosed only after the disease has advanced, a new study is pointing towards a more targeted approach to identifying those at greatest risk.

Researchers who studied more than 2,000 adults across six Nigerian hospitals identified five factors associated with colorectal cancer: family history of cancer, adult height, body size over the course of life, physical activity and processed-meat consumption.

Led by Olusegun Isaac Alatise, MD, the researchers say the findings could inform risk-reduction strategies and targeted early detection, particularly in Nigeria, where expanding universal screening would require substantial investment in healthcare infrastructure, trained personnel and diagnostic capacity.

Published in JAMA Network Open, the study examined 13 potential risk factors. Five showed statistically significant associations with colorectal cancer after adjustment for other factors.

Participants with a family history of cancer had 55% higher odds of colorectal cancer than those without one. Adult height was also associated with risk, with the odds increasing by about 9% for every 5cm increase in height.

The researchers found an even stronger association with body size over adulthood. Participants in the largest body-size group had almost twice the odds of colorectal cancer compared with those in the leanest group, supporting healthy weight maintenance as a potential prevention strategy.

Physical activity was associated with lower risk. Compared with the least-active group, those in the second activity group had 37% lower odds of colorectal cancer, while those in the third group had about 48% lower odds.

Of the dietary factors examined, processed meat was the only one significantly associated with colorectal cancer. Those in the highest consumption group had 43% higher odds than participants in the lowest group.

The study found no significant associations with red meat, fruit, vegetables, fibre, smoking, alcohol or diabetes after adjustment. The researchers caution that some conventional risk factors may have been difficult to assess because of their low prevalence or limited variation among participants.

The findings suggest that colorectal cancer in Nigeria shares important risk patterns with those observed in high-income countries, although further research is needed to establish how these factors operate across different African populations.

The study comes against a worrying backdrop. About 88% of colorectal cancers diagnosed in Nigerians are already at stage III or IV, while previous research cited by the investigators found that only 5% of screening-eligible adults in one Nigerian community had ever been screened.

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Colorectal cancer is becoming an increasingly important public health challenge in Nigeria and across sub-Saharan Africa. Globally, the disease accounts for about 1.9 million new diagnoses and 1 million deaths annually, while Africa is projected to experience one of the sharpest increases in cases and deaths in coming decades.

The researchers say the findings offer a different way of approaching colorectal cancer prevention in Nigeria.

According to him, rather than relying exclusively on population-wide screening, which the country may not yet have the resources to provide, researchers could develop a locally relevant approach to identify people whose risk is high enough to justify earlier or more intensive screening.

They added that such a risk-prediction model could eventually help doctors and health authorities direct scarce screening resources towards those most likely to benefit. However, further studies are needed to validate the findings before such a tool can be adopted.

They said that public awareness is another major challenge. Only 22.5% of participants had heard of colorectal cancer before joining the study, and only about half of those aware of the disease believed that risk factors contributed to its development.

The researchers pointed to primary healthcare facilities, radio, television and community-based education as potential channels for improving awareness and promoting early detection.

According to them, ultimately, the study gives Nigeria a stronger evidence base for identifying people who may be at greater risk.

They added that the next step will be to determine whether these findings can be translated into a reliable tool that helps shift the country’s colorectal cancer response from one dominated by late diagnosis towards earlier detection and more effective prevention.

The researchers called for studies in other Nigerian populations and across West and sub-Saharan Africa to determine whether the associations are consistent, as well as research into risk factors particularly relevant to African populations, including genetic, environmental, dietary, infectious, metabolic and socioeconomic influences.