Very high incidence of familial colorectal cancer in Newfoundland: A comparison with Ontario and 13 other population-based studies

Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada.
Familial Cancer (Impact Factor: 1.98). 02/2007; 6(1):53-62. DOI: 10.1007/s10689-006-9104-x
Source: PubMed


Newfoundland has the highest rate of colorectal cancer (CRC) of any Canadian province. In order to investigate the factors, especially genetic components, responsible for CRC we established the Newfoundland Colorectal Cancer Registry. In a 5-year period we examined every case of CRC diagnosed under the age of 75 years and obtained consent from 730 cases. Careful analysis of family history was used to assign a familial cancer risk, based on established criteria. We observed that 3.7% of CRC cases came from families meeting the Amsterdam II criteria and a further 0.9% of cases involved familial adenomatous polyposis (FAP). An additional 43% of cases met one or more of the revised Bethesda criteria and 31% of all cases had a first-degree relative affected with CRC. We compared the Newfoundland data with data from the province of Ontario, where the same recruitment and risk-assessment criteria were used. In all categories, the indicators of familial risk were significantly higher in Newfoundland. These data were also compared to results published from 13 other population-based studies worldwide. In every category the proportion of Newfoundland cases meeting the criteria was higher than in any other population. The mean differences were: 3.5-fold greater for FAP, 2.8-fold higher for Amsterdam criteria, 2.0-fold higher for Bethesda criteria and 1.9-fold higher for the number of affected first-degree relatives. We conclude that the high incidence of CRC in Newfoundland may be attributable to genetic, or at least familial, factors. In the high-risk families we provide evidence for the involvement of founder mutations in the APC and MSH2 genes.

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    • "Participants were drawn from two locations in Canada: Ottawa, Ontario (ON) and St John's, Newfoundland (NL). Ottawa is a large, mostly urban population with CRC incidence reflecting the Canadian average and overall relatively high socio-economic status, whereas St John's is a smaller urban population with a high incidence of CRC (Green et al. 2007; Woods et al. 2005) and a broader socio-economic mix. Additionally, ON and NL have different newborn screening programs in terms of both organization and number of conditions included. "
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    • "NL is one of the 13 provinces/territories in Canada and has the highest incidence of colorectal cancer as well as one of the highest cancer mortality rates in Canada [1], [28]. This population is also characterized by a high incidence rate of familial colorectal cancer [29], [30]. A strength of our study is the long period of time that patients have been followed (up to 12.5 years after cancer diagnosis). "
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    • "Thus, our findings may help, in part, reconcile some discrepancies in the literature in terms of the risk for CRC related to alcohol drinking and provide some evidence for assessing possible interactions between alcohol and obesity in future epidemiological studies. Another possible reason for this may be that NL is a founder population geographically isolated [30]. A higher proportion of CRC incidence in NL may be mainly attributed to genetic cause that may shade the roles of other environmental factors in the CRC carcinogenesis such as alcohol consumption [19,30]. "
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