Microsatellite Instability Is Common in Colorectal Cancer in Native Nigerians

Colorectal cancer (CRC) is the fifth most common cancer in Africa, with significant differences in incidence, biology and clinical behavior from other populations.

We studied prevalence and clinicopathological features of microsatellite instability (MSI) and young onset CRC in 83 archival samples from the University of Ibadan, Nigeria.

Nigerian cases of CRC were MSI-high in 43% and MSI-high CRC had significantly lower histological heterogeneity than microsatellite-stable CRC (20% vs. 55% respectively, p=0.046). Presence of signet ring cell differentiation (10-50% of tumor) was significantly higher in younger patients with CRC (<50 years) (odds ratio(OR)=5.93, 95% confidence interval(CI)=1.17-29.95, p=0.038). Poor differentiation (34%), invasive growth (96%), and high prevalence of mucinous (10%) and signet ring cell adenocarcinomas (4%) were among distinct features of Nigerian patients with CRC.

MSI-high CRC is more common in West Africa and more detailed molecular and genetic analysis is warranted as CRC incidence and mortality continue to increase in the Sub-Saharan Africa.