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- Dahlin, Anna M, 1979-, et al.
(författare)
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Plasma vitamin B12 concentrations and the risk of colorectal cancer : a nested case-referent study
- 2008
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 32:2, s. 304-314
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Tidskriftsartikel (refereegranskat)abstract
- In this nested case-referent study, we related plasma concentrations of vitamin B12 to the risk of colorectal cancer, taking into consideration prediagnostic plasma folate and total homocysteine concentrations. Subjects were 226 cases and double matched referents from the population-based Northern Sweden Health and Disease Study. Follow-up times from recruitment to diagnosis ranged from 0.1 to 12.7 years, with a median of 4.2 years. Plasma vitamin B12 concentrations were inversely associated with the risk of rectal cancer: univariate odds ratio for the highest versus lowest quintile 0.34 (95% confidence interval (95% CI) 0.13-0.83), p(trend) = 0.004. Risk estimates were attenuated slightly but remained statistically significant after adjustment for body mass index, current smoking, recreational and occupational physical activity, alcohol intake and prediagnostic plasma folate and total homocysteine concentrations: OR 0.30 (95% CI 0.08-0.99), p(trend) = 0.025. The corresponding univariate and fully adjusted odds ratios for colon cancer were 1.25 (CI 0.66-2.36), p(trend) = 0.185 and 1.42 (CI 0.67-3.05), p(trend) = 0.113, respectively. The observed over-risk was attributable to left-sided colon cancer. Interaction analyses including vitamin B12, folate and homocysteine were in line with the results for vitamin B12 alone. In conclusion, these results suggest that increasing levels of plasma vitamin B12, alone or together with other factors involved in one-carbon metabolism, may reduce the risk of rectal cancer, whereas for colon cancer, the association appears to be less clear.
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| 2. |
- Eklöf, Vincy, et al.
(författare)
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The reduced folate carrier (RFC1) 80G>A and folate hydrolase 1 (FOLH1) 1561C>T polymorphisms and the risk of colorectal cancer : a nested case-referent study
- 2008
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 68:5, s. 393-401
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Polymorphisms in genes involved in folate uptake and metabolism may affect folate status and, thereby, the risk of cancer. In this nested case‐referent study, we related two such polymorphisms, reduced folate carrier (RFC1) 80G>A and folate hydrolase 1 (FOLH1) 1561C>T, to the risk of colorectal cancer, taking into account pre‐diagnostic plasma folate and total homocysteine concentrations and the MTHFR 677C>T polymorphism, which were analysed in a previous study.Material and methods. Subjects were 220 cases and 414 matched referents from the population‐based Northern Sweden Health and Disease Study.Results. The RFC1 80A‐allele was associated with reduced plasma folate and elevated plasma total homocysteine concentrations, but the result was statistically significant only for folate. In contrast, the FOLH1 1561T‐allele was associated with higher plasma folate and reduced plasma total homocysteine concentrations, and the result was statistically significant only for homocysteine. Neither polymorphism was related to the risk of colorectal cancer, either in univariate analysis or after adjusting for body mass index, current smoking, recreational and occupational physical activity and alcohol intake. Further adjustment for folate or homocysteine status or the MTHFR 677C>T polymorphism did not affect risk estimates. Subjects with the RFC1 80AA genotype in combination with low plasma folate concentrations or the MTHFR 677TT genotype had a reduced risk of colorectal cancer of borderline statistical significance.Conclusions. These findings suggest that although the RFC1 80G>A and FOLH1 1561C>T polymorphisms may influence folate status, they are not likely to have a major independent role in the development of colorectal cancer.Read More: http://informahealthcare.com/doi/abs/10.1080/00365510701805431
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