Determine whether colorectal cancer (CRC) rates are disproportionately high in the French-Acadian region (population 1.2 million) of Louisiana, home of the Cajuns, a founder population.
2005–2009 cancer incidence rates were stratified by age/race/gender in the 18 Acadian parish region and 9-parish subgroup with higher proportions of French speakers and compared with Louisiana and United States rates. Parishes were identified through language census data. A total of 3,288 CRC cases were identified in the Acadian region and 11,737 in Louisiana.
CRC rates in whites and white males in the 18 parishes were statistically significantly higher than both Louisiana and US rates. In the 9 parishes, rates increased further; whites had an incidence of 56.1/100,000, 13% higher than Louisiana (P<0.0003) and 23% higher than US rates (P<0.0001). In white males, incidence was 72.6/100,000, 19% higher than Louisiana (P<0.0002) and 37% higher than US rates (P<0.0001). If the 9-parish regions were considered a “state,” white males would have the highest CRC incidence in the United States by 11% (P<0.0175) compared with other white male populations.
CRC rates are among the highest in the United States, increasing with the proportion of French speakers, a marker for the Cajun population. This appears to be the first study identifying a high rate of cancer in a large, regional, US founder population, raising the possibility of a genetic predisposition. Alternatively, an unidentified, robust environmental risk factor may be present. Future studies are needed to identify genetic and/or other risk factors in this population.