%0 Journal Article
%T Subsite-Specific Dietary Risk Factors for Colorectal Cancer: A Review of Cohort Studies
%A Anette Hjart£¿ker
%A Bjarte Aagnes
%A Trude Eid Robsahm
%A Hilde Langseth
%A Freddie Bray
%A Inger Kristin Larsen
%J Journal of Oncology
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/703854
%X Objective. A shift in the total incidence from left- to right-sided colon cancer has been reported and raises the question as to whether lifestyle risk factors are responsible for the changing subsite distribution of colon cancer. The present study provides a review of the subsite-specific risk estimates for the dietary components presently regarded as convincing or probable risk factors for colorectal cancer: red meat, processed meat, fiber, garlic, milk, calcium, and alcohol. Methods. Studies were identified by searching PubMed through October 8, 2012 and by reviewing reference lists. Thirty-two prospective cohort studies are included, and the estimates are compared by sex for each risk factor. Results. For alcohol, there seems to be a stronger association with rectal cancer than with colon cancer, and for meat a somewhat stronger association with distal colon and rectal cancer, relative to proximal colon cancer. For fiber, milk, and calcium, there were only minor differences in relative risk across subsites. No statement could be given regarding garlic. Overall, many of the subsite-specific risk estimates were nonsignificant, irrespective of exposure. Conclusion. For some dietary components the associations with risk of cancer of the rectum and distal colon appear stronger than for proximal colon, but not for all. 1. Introduction Global estimates for 2008 indicate that colorectal cancer is the third most common cancer in the world [1]. Reports in several countries have described diverging incidence rates in colorectal cancer by subsite, including, in relative terms, an increasing proportion of proximal tumors [2¨C15], and thus a shift in absolute incidence from left- to right-sided colon cancers. The reasons for this trend are not well understood; the subsites differ in physical function, artery supply, histology, and innervation, and they also derive from different segments in the primitive intestinal tract in the embryo [16]. The proximal colon originates from the midgut, whereas the distal colon and the rectum derivate originate from the hindgut. Comparisons have also shown that proximal colon tumors tend to have different molecular characteristics, with a higher proportion of microsatellite instability, and are more likely to have CpG island methylator phenotype and Ki-ras mutations than distal colon and rectal tumors [17]. It has been estimated that 45 percent of all colorectal cancer cases can be prevented in high-risk populations through modifications of diet, physical activity habits, and weight control [18]. According to the recent report
%U http://www.hindawi.com/journals/jo/2013/703854/