Ethnic differences in colon and rectal cancer incidence in Nigeria: A case of dietary determinants?

Background: Colorectal cancer has for a long time occurred at lower rates in the native Africans than in the Caucasians. The reasons adduced include lack of pre-malignant conditions like polyps and ulcerative colitis and mostly to the high fiber, low animal protein diet that Africans consume. Nigeria has a low colorectal cancer incidence and within this milieu the incidence between the various ethnic tribes also varies with some particular tribes exhibiting negligible incidence rates. If moving from a location of low colorectal cancer incidence to one of high colorectal cancer incidence predisposes one to develop the disease, could not the converse apply and those with a predisposition to developing the disease experience some protection when they live or interact with those with negligible predisposition? Aim: This study is aimed at giving an impetus to research within the ethnic regions of Nigeria with the lowest colorectal cancer incidence in a bid to unravel the cancer preventive factors either in their diet or environment for the good of those from the Western world. Materials and Methods: This is a retrospective study utilizing the records of patients who had surgery for colorectal cancer at the University College Hospital Ibadan, Nigeria, between 2002 and 2010 with particular attention to the ethnic groups to which they belong. Results: From 2002 to 2010, a total of 500 colorectal cancer cases were operated on at the University College Hospital (UCH) Ibadan, giving an annual rate of about 63 patients. Out of these patients, 73% were Yoruba (the dominant and indigenous ethnic group in Ibadan), 13.5% were Ibo, and 12.9% were from Bendel, while Hausa, cross-river and rivers made up the remaining 1.5%, 1.8% and 0.5%, respectively. Conclusion: There is no doubt that while Nigeria as a whole is regarded as a country with low colorectal cancer incidence, there are regions within the country where the incidence is almost negligible. I believe further research into these areas may improve our understanding of chemo-preventive factors, which can only augur well for the global measures in the prevention and management of colorectal cancer.