My overall research aim is to understand the effects of diet on colorectal adenomas, known precursors of colorectal cancer. We recently completed the Polyp Prevention Trial (PPT) a large-scale multi-center dietary intervention clinical trial to examine the effect of a low-fat, high-fiber, high-fruit and vegetable intervention on recurrence of adenomatous polyps of the colorectum. There was no effect of a comprehensive dietary intervention on the recurrence of colorectal adenomas during the four years of the trial, however, since diet may affect early molecular and cellular events in colorectal neoplasia, a statistically significant intervention effect may emerge after the four years of the trial. Data analysis is just beginning on the PPT Continued Follow-up Study, which has collected 8 year post-baseline follow-up data on 1357 participants. I am also conducting a number of sub-studies in the PPT to better understand the epidemiology of colorectal adenomas. One dietary finding in the PPT cohort is that legumes intake was significantly associated with both adenoma recurrence and advanced adenoma recurrence. The odds ratio (OR) comparing the lowest to the highest quartiles for advanced adenomas was OR=0.30, 95% CI=0.15-0.60, and there was a significant trend. Legumes are a rich source of fermentable dietary fibers which are precursors of luminal butyrate. The anti-inflammatory actions of butyrate are supported by both clinical and animal studies, and the anti-neoplastic effects of butyrate have been demonstrated in various in vitro systems. In addition, legumes have a low glycemic index (GI). A high glycemic index diet is associated with both type 2 diabetes (DM) and colon cancer risk and a number of epidemiologic studies have provided convincing evidence for an association between DM, insulin resistance (IR) and colon cancer. Additionally, both insulin resistance and colorectal cancer are increasingly recognized as chronic, low-level, inflammatory states. The Colon Cancer Prevention Group is conducting a number of studies to further understand the role inflammation and insulin resistance in colon cancer and the role of diet in mediating these risks. A controlled feeding study in men with a history of adenomas is being conducted to understand whether legumes increases fecal butyrate, decreases circulating inflammatory cytokines and acute phase proteins, and alters gene expression in fecal colonocytes. The effects of diet on gene expression in exfoliated cells should provide insights on dietary induced changes in colonic epithelial. We recently initiated study on the effects of legumes and legume components on the inhibition of colon carcinogenesis in azoxymethane (AOM) induced colon cancers in male and female C57BL/6J Ob/Ob mice. This project will help us understand whether fiber or other phytochemical components of legumes are responsible for the reduction in adenoma recurrence, and the mechanisms relating obesity, insulin resistance and colon cancer. While data suggest that inflammatory mediators are elevated in patients with colon cancer, and may in fact, be elevated in subjects with adenomatous polyps, it is unclear at this time if the inflammatory cytokines reported are produced by the transformed epithelial cells and/or immune cells in the polyp or if a state of chronic inflammation induced by obesity and or insulin resistance increases the likelihood of polyp formation and/or reoccurrence. Current studies are underway to address these issues. To investigate the inter-individual variation in the diet and adenoma associations, interactions between dietary factors and single nucleotide polymorphisms SNPs in specific genes in the PPT was undertaken. The initial analysis will focus on three areas: 1. Genes related to obesity, BMI, body fat distribution, hyperinsulinemia, and inflammation, 2. Genes related to behavior, i.e. making and maintaining dietary changes have a genetic component, 3. genes related to DNA repair. Knowing what dietary factors are associated with cancer risk reduction is important, but not sufficient for cancer prevention. Research clearly suggests that dietary changes are difficult both to initiate and to maintain. Therefore, we are trying to understand factors associated with making dietary change in the PPT intervention by examining a variety of baseline and trial behaviors variables associated with success in achieving the PPT fat, fiber, and fruit and vegetables goals

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Intramural Research (Z01)
Project #
1Z01CN000151-19
Application #
7593151
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
19
Fiscal Year
2007
Total Cost
$416,005
Indirect Cost
Name
Division of Cancer Prevention and Control
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Brown, David A; Hance, Kenneth W; Rogers, Connie J et al. (2012) Serum macrophage inhibitory cytokine-1 (MIC-1/GDF15): a potential screening tool for the prevention of colon cancer? Cancer Epidemiol Biomarkers Prev 21:337-46
Murphy, Gwen; Cross, Amanda J; Sansbury, Leah S et al. (2009) Dopamine D2 receptor polymorphisms and adenoma recurrence in the Polyp Prevention Trial. Int J Cancer 124:2148-51
Lanza, Elaine; Yu, Binbing; Murphy, Gwen et al. (2007) The polyp prevention trial continued follow-up study: no effect of a low-fat, high-fiber, high-fruit, and -vegetable diet on adenoma recurrence eight years after randomization. Cancer Epidemiol Biomarkers Prev 16:1745-52
Wanke, Kay L; Daston, Cassandra; Slonim, Amy et al. (2007) Adherence to the polyp prevention trial dietary intervention is associated with a behavioral pattern of adherence to nondietary trial requirements and general health recommendations. J Nutr 137:391-8
Jacobs, Elizabeth T; Lanza, Elaine; Alberts, David S et al. (2006) Fiber, sex, and colorectal adenoma: results of a pooled analysis. Am J Clin Nutr 83:343-9
Lanza, Elaine; Hartman, Terryl J; Albert, Paul S et al. (2006) High dry bean intake and reduced risk of advanced colorectal adenoma recurrence among participants in the polyp prevention trial. J Nutr 136:1896-903
Sansbury, Leah B; Bergen, Andrew W; Wanke, Kay L et al. (2006) Inflammatory cytokine gene polymorphisms, nonsteroidal anti-inflammatory drug use, and risk of adenoma polyp recurrence in the polyp prevention trial. Cancer Epidemiol Biomarkers Prev 15:494-501
Woodson, Karen; Weisenberger, Daniel J; Campan, Mihaela et al. (2005) Gene-specific methylation and subsequent risk of colorectal adenomas among participants of the polyp prevention trial. Cancer Epidemiol Biomarkers Prev 14:1219-23
Pabby, Ajay; Schoen, Robert E; Weissfeld, Joel L et al. (2005) Analysis of colorectal cancer occurrence during surveillance colonoscopy in the dietary Polyp Prevention Trial. Gastrointest Endosc 61:385-91
Cantwell, Marie M; Forman, Michele R; Albert, Paul S et al. (2005) No association between fatty acid intake and adenomatous polyp recurrence in the polyp prevention trial. Cancer Epidemiol Biomarkers Prev 14:2059-60

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