Leah B. Sansbury

Dietary Flavonoids and Colorectal Adenoma Recurrence in the Polyp Prevention Trial

Two recent case-control studies suggested that some flavonoid subgroups may play a role in preventing colorectal cancer. Previous prospective cohort studies generally reported no association; however, only a small subset of flavonoids was evaluated and partial flavonoid databases were used. We used the newly constructed U.S. Department of Agriculture flavonoid database to examine the association between consumption of total flavonoids, 6 flavonoid subgroups, and 29 individual flavonoids with adenomatous polyp recurrence in the Polyp Prevention Trial. The Polyp Prevention Trial was a randomized dietary intervention trial, which examined the effectiveness of a low-fat, high-fiber, high-fruit, and high-vegetable diet on adenoma recurrence. Intakes of flavonoids were estimated from a food frequency questionnaire. Multivariate logistic regression models (adjusted for age, body mass index, sex, regular non–steroidal anti-inflammatory use, and dietary fiber intake) were used to estimate odds ratios and 95% confidence intervals for both any and advanced adenoma recurrence within quartiles of energy-adjusted flavonoid intake (baseline, during the trial, and change during the trial). Total flavonoid intake was not associated with any or advanced adenoma recurrence. However, high intake of flavonols, which are at greater concentrations in beans, onions, apples, and tea, was associated with decreased risk of advanced adenoma recurrence (4th versus 1st quartile during the trial; odds ratio, 0.24; 95% confidence interval, 0.11, 0.53; Ptrend = 0.0006). Similar inverse associations were observed to a smaller extent for isoflavonoids, the flavonol kaempferol, and the isoflavonoids genistein and formononetin. Our data suggest that a flavonol-rich diet may decrease the risk of advanced adenoma recurrence. (Cancer Epidemiol Biomarkers Prev 2008;17(6):1344–53)

Variant ABO blood group alleles, secretor status, and risk of pancreatic cancer: results from the pancreatic cancer cohort consortium

Background: Subjects with non-O ABO blood group alleles have increased risk of pancreatic cancer. Glycosyltransferase activity is greater for the A1 versus A2 variant, whereas O01 and O02 variants are nonfunctioning. We hypothesized: 1) A1 allele would confer greater risk than A2 allele, 2) protective effect of the O allele would be equivalent for O01 and O02 variants, 3) secretor phenotype would modify the association with risk. Methods: We determined ABO variants and secretor phenotype from single nucleotide polymorphisms in ABO and FUT2 genes in 1,533 cases and 1,582 controls from 12 prospective cohort studies. Adjusted odds ratios (OR) for pancreatic cancer were calculated using logistic regression. Results: An increased risk was observed in participants with A1 but not A2 alleles. Compared with subjects with genotype O/O, genotypes A2/O, A2/A1, A1/O, and A1/A1 had ORs of 0.96 (95% CI, 0.72–1.26), 1.46 (95% CI, 0.98–2.17), 1.48 (95% CI, 1.23–1.78), and 1.71 (95% CI, 1.18–2.47). Risk was similar for O01 and O02 variant O alleles. Compared with O01/O01, the ORs for each additional allele of O02, A1, and A2 were 1.00 (95% CI, 0.87–1.14), 1.38 (95% CI, 1.20–1.58), and 0.96 (95% CI, 0.77–1.20); P, O01 versus O02 = 0.94, A1 versus A2 = 0.004. Secretor phenotype was not an effect modifier (P-interaction = 0.63). Conclusions: Among participants in a large prospective cohort consortium, ABO allele subtypes corresponding to increased glycosyltransferase activity were associated with increased pancreatic cancer risk. Impact: These data support the hypothesis that ABO glycosyltransferase activity influences pancreatic cancer risk rather than actions of other nearby genes on chromosome 9q34. Cancer Epidemiol Biomarkers Prev; 19(12); 3140–9. ©2010 AACR.

Variant ABO Blood Group Alleles, Secretor Status, and Risk of Pancreatic Cancer: Results from the Pancreatic Cancer Cohort Consortium

Background: Subjects with non-O ABO blood group alleles have increased risk of pancreatic cancer. Glycosyltransferase activity is greater for the A1 versus A2 variant, whereas O01 and O02 variants are nonfunctioning. We hypothesized: 1) A1 allele would confer greater risk than A2 allele, 2) protective effect of the O allele would be equivalent for O01 and O02 variants, 3) secretor phenotype would modify the association with risk. Methods: We determined ABO variants and secretor phenotype from single nucleotide polymorphisms in ABO and FUT2 genes in 1,533 cases and 1,582 controls from 12 prospective cohort studies. Adjusted odds ratios (OR) for pancreatic cancer were calculated using logistic regression. Results: An increased risk was observed in participants with A1 but not A2 alleles. Compared with subjects with genotype O/O, genotypes A2/O, A2/A1, A1/O, and A1/A1 had ORs of 0.96 (95% CI, 0.72–1.26), 1.46 (95% CI, 0.98–2.17), 1.48 (95% CI, 1.23–1.78), and 1.71 (95% CI, 1.18–2.47). Risk was similar for O01 and O02 variant O alleles. Compared with O01/O01, the ORs for each additional allele of O02, A1, and A2 were 1.00 (95% CI, 0.87–1.14), 1.38 (95% CI, 1.20–1.58), and 0.96 (95% CI, 0.77–1.20); P, O01 versus O02 = 0.94, A1 versus A2 = 0.004. Secretor phenotype was not an effect modifier (P-interaction = 0.63). Conclusions: Among participants in a large prospective cohort consortium, ABO allele subtypes corresponding to increased glycosyltransferase activity were associated with increased pancreatic cancer risk. Impact: These data support the hypothesis that ABO glycosyltransferase activity influences pancreatic cancer risk rather than actions of other nearby genes on chromosome 9q34. Cancer Epidemiol Biomarkers Prev; 19(12); 3140–9. ©2010 AACR.

Serum Macrophage Inhibitory Cytokine-1 (MIC-1/GDF15): A Potential Screening Tool for the Prevention of Colon Cancer?

Background: Macrophage inhibitory cytokine-1 (MIC-1/GDF15) mediates nonsteroidal anti-inflammatory drug (NSAID) protection from colonic polyps in mice and is linked to the development of colorectal carcinoma in humans. Therefore, changes in serum MIC-1/GDF15 levels could predict the presence of premalignant colonic polyposis and assist in population screening strategies. Methods: Serum MIC-1/GDF15 levels were measured in subjects in the Polyp Prevention Trial, in which NSAID use and colon cancer risk factors were defined. Subjects had an initial adenoma removed, a repeat colonoscopy removing previously unidentified polyps, and serum MIC-1/GDF15 estimation. Three years later recurrent adenomas were identified and serum MIC-1/GDF15 levels reestimated. The relationship between serum MIC-1/GDF15 levels and adenoma presence or recurrence was examined. Results: Serum MIC-1/GDF15 levels differed by adenoma status and were significantly related to colon cancer risk factors. In addition, mean serum MIC-1/GDF15 levels rose with increasing numbers of adenomas present and high-risk adenoma recurrence. NSAID users had higher serum MIC-1/GDF15 concentrations, which were related to protection from adenoma recurrence. Furthermore, adjusted serum MIC-1/GDF15 levels at final follow-up were related to adenoma recurrence (highest quartile MIC-1/GDF15; OR = 14.7, 95% CI: 3.0–73). Conclusions: These data suggest that MIC-1/GDF15 mediates at least some of the protection afforded by NSAIDs against human colonic polyposis. Furthermore, serum MIC-1/GDF15 levels vary with the development of adnenomatous colonic polyps. Impact: Serum MIC-1/GDF15 determination may hold promise as the first serum screening test to assist the detection of premalignant adenomatous colonic polyposis. Cancer Epidemiol Biomarkers Prev; 21(2); 337–46. ©2011 AACR.

Cancer Pharmacogenomics and Pharmacoepidemiology: Setting a Research Agenda to Accelerate Translation

Recent advances in genomic research have demonstrated a substantial role for genomic factors in predicting response to cancer therapies. Researchers in the fields of cancer pharmacogenomics and pharmacoepidemiology seek to understand why individuals respond differently to drug therapy, in terms of both adverse effects and treatment efficacy. To identify research priorities as well as the resources and infrastructure needed to advance these fields, the National Cancer Institute (NCI) sponsored a workshop titled “Cancer Pharmacogenomics: Setting a Research Agenda to Accelerate Translation” on July 21, 2009, in Bethesda, MD. In this commentary, we summarize and discuss five science-based recommendations and four infrastructure-based recommendations that were identified as a result of discussions held during this workshop. Key recommendations include 1) supporting the routine collection of germline and tumor biospecimens in NCI-sponsored clinical trials and in some observational and population-based studies; 2) incorporating pharmacogenomic markers into clinical trials; 3) addressing the ethical, legal, social, and biospecimen- and data-sharing implications of pharmacogenomic and pharmacoepidemiologic research; and 4) establishing partnerships across NCI, with other federal agencies, and with industry. Together, these recommendations will facilitate the discovery and validation of clinical, sociodemographic, lifestyle, and genomic markers related to cancer treatment response and adverse events, and they will improve both the speed and efficiency by which new pharmacogenomic and pharmacoepidemiologic information is translated into clinical practice.

Cyclooxygenase-2 Polymorphisms, Aspirin Treatment, and Risk for Colorectal Adenoma Recurrence—Data from a Randomized Clinical Trial

Cyclooxygenase-2 (COX-2) catalyzes the rate-limiting step in the production of prostaglandins, potent mediators of inflammation. Chronic inflammation plays an important role in the development and progression of colorectal cancer. Aspirin inhibits COX-2 activity and lowers the risk for colorectal adenomas and cancer. We investigated whether common genetic variation in COX-2 influenced risk for colorectal adenoma recurrence among 979 participants in the Aspirin/Folate Polyp Prevention Study who were randomly assigned to placebo or aspirin and followed for 3 years for the occurrence of new adenomas. Of these participants, 44.2% developed at least one new adenoma during follow-up. Adjusted relative risks and 95% confidence intervals (95% CI) were calculated to test the association between genetic variation at six COX-2 single-nucleotide polymorphisms and adenoma occurrence and interaction with aspirin treatment. Two single-nucleotide polymorphisms were significantly associated with increased adenoma recurrence: for rs5277, homozygous carriers of the minor C allele had a 51% increased risk compared with GG homozygotes (relative risk, 1.51; 95% CI, 1.01-2.25), and for rs4648310, heterozygous carriers of the minor G allele had a 37% increased risk compared with AA homozygotes (relative risk, 1.37; 95% CI, 1.05-1.79). (There were no minor allele homozygotes.) In stratified analyses, there was suggestive evidence that rs4648319 modified the effect of aspirin. These results support the hypothesis that COX-2 plays a role in the etiology of colon cancer and may be a target for aspirin chemoprevention and warrant further investigation in other colorectal adenoma and cancer populations.(Cancer Epidemiol Biomarkers Prev 2009;18(10):2726–33)

Hyperplastic Polyps and the Risk of Adenoma Recurrence in the Polyp Prevention Trial

BACKGROUND AND AIMS Recent studies have suggested that some hyperplastic polyps may be associated with an increased risk of colorectal cancer. Prospective information on the risk of adenoma recurrence associated with hyperplastic polyps is limited. We sought to investigate whether the coexistence of hyperplastic polyps with adenomas increases the risk of adenoma recurrence. METHODS We used unconditional logistic regression models to examine the association between baseline hyperplastic polyps and subsequent adenoma recurrence during a 3-year follow-up evaluation, among 1637 participants in the Polyp Prevention Trial. RESULTS A total of 437 participants (26.7%) had hyperplastic polyps coexisting with adenomas at baseline. Of these, 132 (30.2%) had at least one hyperplastic polyp in the proximal colon, whereas 305 (69.8%) had only distal hyperplastic polyps. When compared with subjects without any hyperplastic polyps at baseline, there was no statistically significant association between the presence of baseline hyperplastic polyps and recurrence of any adenoma (odds ratio [OR], 1.19; 95% confidence interval [CI], 0.94-1.51) or advanced adenoma (OR, 1.25; 95% CI, 0.78-2.03). Also, there was no association between hyperplastic polyp location and adenoma recurrence (OR, 1.01; 95% CI, 0.69-1.48) for any proximal hyperplastic polyp (OR, 1.26; 95% CI, 0.96-1.65) and for distal hyperplastic polyps. CONCLUSIONS The coexistence of hyperplastic polyps with adenomas, irrespective of location, does not confer an increased risk of adenoma recurrence beyond that of adenomas alone within 3 years of follow-up evaluation. Prospective long-term studies on adenoma recurrence risk associated with hyperplastic polyps in screening populations are needed.

Serum Adiponectin, Leptin, C-Peptide, Homocysteine, and Colorectal Adenoma Recurrence in the Polyp Prevention Trial

Background: Serum adiponectin, leptin, C-peptide, and homocysteine are indicators for obesity, hyperinsulinemia, and chronic inflammation, which have all been associated with colorectal cancer. Aims: To determine whether serum adiponectin, leptin, C-peptide, and homocysteine are associated with fat, fiber, fruit and vegetable, flavonol, or dry bean intake and colorectal adenoma recurrence. Methods: Using logistic regression, we estimated odds ratios (OR) and 95% confidence intervals (95% CI) for adenoma recurrence in 627 participants from the control arm of the Polyp Prevention Trial, a 4-year trial that examined the effectiveness of a low-fat, high-fiber, high-fruit and vegetable diet on adenoma recurrence. Results: Serum concentrations of C-peptide and homocysteine were inversely related to fiber, fruit and vegetable, and flavonol intake and positively related to percentage of calories from fat (all Ptrend ≤0.01). High homocysteine concentrations were associated with any (4th versus 1st quartile: OR, 2.26; 95% CI, 1.30-3.94) and more than one adenoma recurrence (OR, 2.11; 95% CI, 1.01-4.40). Individuals in the highest, versus lowest, tertile of serum leptin concentration had a decreased risk of advanced adenoma recurrence (OR, 0.22; 95% CI, 0.06-0.79). Conclusion: Our results suggest that serum homocysteine may serve as an indicator of dietary exposure, including a low-fat and high-fiber, high-fruit and vegetable, and high-flavonol diet, as well as colorectal adenoma recurrence. Impact: Discovering biomarkers that are both modifiable and can predict cancer risk is critical. We identified serum homocysteine as a novel indicator that is modified by diet and predicts risk of adenoma recurrence. Cancer Epidemiol Biomarkers Prev; 19(6); 1441–52. ©2010 AACR.

Inflammatory Cytokine Gene Polymorphisms, Nonsteroidal Anti-Inflammatory Drug Use, and Risk of Adenoma Polyp Recurrence in the Polyp Prevention Trial

Background: Pro- and anti-inflammatory cytokine genes may be important in the maintenance and progression of colorectal cancer. It is possible that single-nucleotide polymorphisms in inflammatory genes may play a role in chronic colonic inflammation and development of colorectal adenomas. Furthermore, common variants in cytokine genes may modify the anti-inflammatory effect of nonsteroidal anti-inflammatory drugs (NSAIDs) in the prevention of colorectal cancer. Methods: We examined the association between cytokine gene polymorphisms and risk of recurrent adenomas among 1,723 participants in the Polyp Prevention Trial. We used logistic regression to calculate odds ratios (OR) for the association between genotype, NSAID use, and risk of adenoma recurrence. Results: Cytokine gene polymorphisms were not statistically significantly associated with risk of adenoma recurrence in our study. We observed statistically significant interactions between NSAID use, IL-10 −1082 G>A genotype, and risk of adenoma recurrence (P = 0.01) and multiple adenoma recurrence (P = 0.01). Carriers of the IL-10 −1082 G>A variant allele who were non-NSAID users had a statistically significant decreased risk of multiple adenoma recurrence (OR, 0.43; 95% confidence interval, 0.24-0.77) as well as a nonsignificant 30% decreased risk of any adenoma recurrence. In contrast, NSAID users who were carriers of the IL-10 −1082 G>A variant allele were at an increased risk of any adenoma recurrence (OR, 1.55; 95% confidence interval, 1.00-2.43). Conclusion: These findings suggest that individuals who are carriers of the IL-10 −1082 G>A variant allele may not benefit from the chemoprotective effect of NSAIDs on adenoma polyp recurrence. (Cancer Epidemiol Biomarkers Prev 2006;15(3):494–501)

Maximizing resources to study an uncommon cancer: E2C2 -- Epidemiology of Endometrial Cancer Consortium

Endometrial cancer affects more than 40,000 women a year in the U.S. While the association of this disease with high body mass index and sex steroid hormones is well known, there are many questions about etiology that have not been resolved. Little is known about the genetic basis for risk associated with hormones or obesity, other common genetic factors associated with risk, or gene–environment interactions. E2C2, the Epidemiology of Endometrial Cancer Consortium, was formed in 2006 to provide a collaborative environment for addressing these questions by pooling data from existing studies. This allows for investigations of uncommon risk factors, risk for rare histologic subtypes, and associations within strata that cannot be achieved in individual studies. This report describes the establishment of the consortium, ongoing projects that demonstrate the advantages of collaborative efforts, and challenges faced. Overall, the consortium promises to provide an important means of furthering our knowledge about this cancer.