Dietary Inflammatory Potential and the Risk of Serrated and Adenomatous Colorectal Polyps

Studies of dietary inflammation potential and risks of colorectal cancer precursors are limited, particularly for sessile serrated lesions (SSLs). This study examines the association using the energy-adjusted dietary inflammatory index (E-DIITM), a measure of anti- and/or pro-inflammatory diet, in a large US colonoscopy-based case-control study of 3246 controls, 1530 adenoma cases, 472 hyperplastic polyp cases, and 180 SSL cases. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived from logistic regression models. Analyses were stratified by participant characteristics, and urinary prostaglandin E2 metabolite (PGE-M) and high-sensitivity plasma C-reactive protein (hs-CRP) levels, inflammation biomarkers. Highest E-DII™ intake was associated with significantly increased risks of colorectal adenomas (OR 1.36, 95% CI 1.11, 1.67), and hyperplastic polyps (OR 1.43, 95% CI 1.06, 1.98), compared with participants consuming the lowest E-DII™ quartile. A similar, but non-significant, increased risk was also observed for SSLs (OR 1.41, 95% CI 0.82, 2.41). The positive association was stronger in females (pinteraction <0.001), normal weight individuals (ptrend 0.01), and in individuals with lower inflammatory biomarkers (ptrend 0.02 and 0.01 for PGE-M and hs-CRP, respectively). A high E-DII™ is associated with colorectal polyp risk, therefore promoting an anti-inflammatory diet may aid in preventing colorectal polyps.

Prevalence of Advanced Colorectal Neoplasia in Veterans: Effects of Age, Sex, and Race/Ethnicity

GOAL

We sought to quantify the independent effects of age, sex, and race/ethnicity on risk of colorectal cancer (CRC) and advanced neoplasia (AN) in Veterans.

STUDY

We conducted a retrospective, cross-sectional study of Veterans aged 40 to 80 years who had diagnostic or screening colonoscopy between 2002 and 2009 from 1 of 14 Veterans Affairs Medical Centers. Natural language processing identified the most advanced finding and location (proximal, distal). Logistic regression was used to examine the adjusted, independent effects of age, sex, and race, both overall and in screening and diagnostic subgroups.

RESULTS

Among 90,598 Veterans [mean (SD) age 61.7 (9.4) y, 5.2% (n=4673) were women], CRC and AN prevalence was 1.3% (n=1171) and 8.9% (n=8081), respectively. Adjusted CRC risk was higher for diagnostic versus screening colonoscopy [odds ratio (OR)=3.79; 95% confidence interval (CI), 3.19-4.50], increased with age, was numerically (but not statistically) higher for men overall (OR=1.53; 95% CI, 0.97-2.39) and in the screening subgroup (OR=2.24; 95% CI, 0.71-7.05), and was higher overall for Blacks and Hispanics, but not in screening. AN prevalence increased with age, and was present in 9.2% of men and 3.9% of women [adjusted OR=1.90; 95% CI, 1.60-2.25]. AN risk was 11% higher in Blacks than in Whites overall (OR=1.11; 95% CI, 1.04-1.20), was no different in screening, and was lower in Hispanics (OR=0.74; 95% CI, 0.55-0.98). Women had more proximal CRC (63% vs. 39% for men; P=0.03), but there was no difference in proximal AN (38.3% for both genders).

CONCLUSIONS

Age and race were associated with AN and CRC prevalence. Blacks had a higher overall prevalence of both CRC and AN, but not among screenings. Men had increased risk for AN, while women had a higher proportion of proximal CRC. These findings may be used to tailor when and how Veterans are screened for CRC.

Differences in erythrocyte phospholipid membrane long-chain polyunsaturated fatty acids and the prevalence of fatty acid desaturase genotype among African Americans and European Americans

Numerous studies have reported an association between genetic variants in fatty acid desaturases (FADS1 and FADS2) and plasma or erythrocyte long chain polyunsaturated fatty acid (PUFA) levels. Increased levels of n-6 PUFAs have been associated with inflammation and several chronic diseases, including diabetes and cancer. We hypothesized that genetic variants of FADS that more efficiently convert precursor n-6 PUFA to arachidonic acid (AA) may explain the higher burden of chronic diseases observed in African Americans. To test this hypothesis, we measured the level of n-6 and n-3 PUFAs in erythrocyte membrane phospholipids and genotyped the rs174537 FADS variants associated with higher AA conversion among African American and European American populations. We included data from 1,733 individuals who participated in the Tennessee Colorectal Polyp Study, a large colonoscopy-based case-control study. Erythrocyte membrane PUFA percentages were measured using gas chromatography. Generalized linear models were used to estimate association of race and genotype on erythrocyte phospholipid membrane PUFA levels while controlling for self-reported dietary intake. We found that African Americans have higher levels of AA and a higher prevalence of GG allele compared to whites, 81% vs 43%, respectively. Homozygous GG genotype was negatively associated with precursor PUFAs (linoleic [LA], di-homo-γ-linolenic [DGLA]), positively associated with both product PUFA (AA, docosahexaenoic acid [DHA]), product to precursor ratio (AA to DGLA), an indirect measure of FADs efficiency and increased urinary isoprostane F2 (F2-IsoP) and isoprostane F3 (F3-IsoP), markers of oxidative stress. Increased consumption of n-6 PUFA and LA resulting in increased AA and subsequent inflammation may be fueling increased prevalence of chronic diseases especially in African descent.

Yogurt consumption and colorectal polyps

Diet modifies the risk of colorectal cancer (CRC), and inconclusive evidence suggests that yogurt may protect against CRC. We analysed the data collected from two separate colonoscopy-based case-control studies. The Tennessee Colorectal Polyp Study (TCPS) and Johns Hopkins Biofilm Study included 5446 and 1061 participants, respectively, diagnosed with hyperplastic polyp (HP), sessile serrated polyp, adenomatous polyp (AP) or without any polyps. Multinomial logistic regression models were used to derive OR and 95 % CI to evaluate comparisons between cases and polyp-free controls and case-case comparisons between different polyp types. We evaluated the association between frequency of yogurt intake and probiotic use with the diagnosis of colorectal polyps. In the TCPS, daily yogurt intake v. no/rare intake was associated with decreased odds of HP (OR 0·54; 95 % CI 0·31, 0·95) and weekly yogurt intake was associated with decreased odds of AP among women (OR 0·73; 95 % CI 0·55, 0·98). In the Biofilm Study, both weekly yogurt intake and probiotic use were associated with a non-significant reduction in odds of overall AP (OR 0·75; 95 % CI 0·54, 1·04) and (OR 0·72; 95 % CI 0·49, 1·06) in comparison with no use, respectively. In summary, yogurt intake may be associated with decreased odds of HP and AP and probiotic use may be associated with decreased odds of AP. Further prospective studies are needed to verify these associations.

Meat intake, meat cooking methods, and meat-derived mutagen exposure and risk of sessile serrated lesions

BACKGROUND

Red and processed meat, recognized carcinogens, are risk factors for colorectal neoplasia, including polyps, the precursor for colorectal cancer. The mechanism is unclear. One possible explanation is the mutagenic activity of these foods, perhaps due to generation during cooking [e.g., heterocyclic amine (HCA) intake]. Few studies have evaluated meat intake and sessile serrated lesion (SSL) risk, a recently recognized precursor, and no study has evaluated meat cooking methods and meat-derived mutagens with SSL risk.

OBJECTIVE

We evaluated intakes of meat, meat cooking methods, and inferred meat mutagens with SSL risk and in comparison to risk of other polyps.

METHODS

Meat, well-done meat, and inferred meat mutagen intakes were evaluated. Polytomous logistic regression models were used to estimate ORs and 95% CIs among cases (556 hyperplastic polyp, 1753 adenoma, and 208 SSL) and controls (3804) in the large colonoscopy-based, case-control study, the Tennessee Colorectal Polyp Study.

RESULTS

The highest quartile intakes of red meat (OR: 2.38; 95% CI: 1.44, 3.93), processed meat (OR: 2.03; 95% CI: 1.30, 3.17), well-done red meat (OR: 2.19; 95% CI: 1.34, 3.60), and the HCA 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQX; OR: 2.48; 95% CI: 1.49, 4.16) were associated with increased risk of SSLs in comparison to the lowest quartile intake.

CONCLUSIONS

High intakes of red and processed meats are strongly and especially associated with SSL risk and part of the association may be due to HCA intake. Future studies should evaluate other mechanism(s) and the potential for primary prevention.

Virtual Colorectal Cancer Surveillance: Bringing Scope Rate to Target

BACKGROUND

Although endoscopy is recommended at 1 year after colorectal cancer (CRC) resection to detect locally recurrent CRC, earlier work at our Veterans Affairs (VA) facility demonstrated that 35% of patients achieve this metric.

STUDY DESIGN

The interdisciplinary team used quality improvement methods to standardize processes and implement a gastroenterology-managed virtual surveillance clinic. The intervention clinic was implemented in August 2014. Veterans who underwent resection for stage I to III CRC at a single VA facility from January 2010 to December 2017 were included, with those undergoing resection between January 2010 and July 2014 considered pre-intervention and those undergoing resection between August 2014 and December 2017 considered post-intervention. The primary endpoint was the proportion of eligible patients for whom endoscopy was completed within 1 year of resection. Secondary outcomes were the proportion of patients who completed endoscopy within 18 months of resection or at any time post-resection and time to surveillance endoscopy.

RESULTS

A total of 186 patients underwent resection for stage I to III CRC from 2010 to 2017; of these, 160 (86%) were eligible for endoscopy at 1-year post-resection (98 pre-intervention and 62 post-intervention). In the pre-intervention period, 30 of 98 patients (30.6%) underwent surveillance endoscopy within 1 year vs 31 of 62 (50.0%) post-intervention (p = 0.031). When evaluated at 18 months after resection, 56 of 98 patients (57.1%) in the pre-intervention group vs 52 of 62 (83.9%) in the post-intervention group underwent surveillance endoscopy (p = 0.001). Median time from resection to endoscopy decreased during the study period, from 1.19 years pre-intervention (interquartile range 0.93 to 1.74 years) to 1.0 years post-intervention (interquartile range 0.93 to 1.09 years) (p = 0.006).

CONCLUSIONS

Implementation of a virtual surveillance clinic with standardized processes was associated with increased guideline-concordant endoscopic surveillance after CRC resection.

Abstract 964: The association of meat intake, meat cooking methods, and meat-derived mutagen exposure with the risk of sessile serrated polyps

Colorectal polyps are the precursors of colorectal cancer, the second leading cause of cancer death in the United States. Red and processed meat intakes have been associated with an increased risk of conventional colorectal adenomas and are classified as carcinogens by the World Health Organization. The mechanism for the relationship between red and processed meat intakes and adenoma risk remains unclear. An explanation may be the exposure to mutagens derived from meat including heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) which are formed by cooking meats at high temperatures. Although intakes of these meats and mutagens has been associated with risks of conventional adenomas including in our study, no previous study has evaluated risk of sessile serrated polyp (SSPs). SSPs, a more recently recognized precursor lesion for microsatellite instable cancer, were strongly associated with red meat intake in our earlier study. This new study builds on that work by evaluating the associations between meat intake, meat cooking methods, and meat mutagens with risks of SSPs and compares the risks to conventional adenomas and hyperplastic polyps. The analysis is conducted in the Tennessee Colorectal Polyp Study, using polytomous logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (95% CI). Dietary information was collected by a self-administered food frequency questionnaire and telephone interview to ascertain meat intake and doneness. This information was used to estimate the intakes of meats, well-done meats, PAHs, HCAs, and mutagenic activity. Several measures of meat intake were strongly associated with risk of SSPs. Highest quartile levels of total meat intake (OR=2.04; 95% CI: 1.24-3.36, p for trend=0.002), red meat intake (OR=2.32; 95% CI: 1.37-3.91, p for trend&lt;0.001), processed meat intake (OR=1.99, 95% CI: 1.24-3.20, p for trend=0.004), well-done red meat (OR=2.13, 95% CI: 1.28-3.55, p for trend=0.002), well-done processed meat (OR=1.60, 95% CI: 1.06-2.4, p for trend=0.03), and the HCA MeIQx (OR=2.55, 95% CI: 1.50-4.33, p for trend=0.003) were associated with statistically significantly increased risks of SSP in comparison to the lowest intake levels. Most of these associations were stronger for risk of SSP than for the other types of polyps. In particular, MeIQx intake was not associated with risk of conventional adenomas suggesting that the mechanisms by which red meat intake affects polyp risk may be different between the conventional adenoma and serrated pathways. Future studies are needed to confirm the relationship between meat and meat mutagen intake with SSP risk and to further define the mechanism(s) by which intake of these factors affects SSP risk.

Citation Format: Dominique A. Mosley, Harvey J. Murff, Reid M. Ness, Walter E. Smalley, Wei Zheng, Martha J. Shrubsole. The association of meat intake, meat cooking methods, and meat-derived mutagen exposure with the risk of sessile serrated polyps [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 964.

Arachidonic acid and colorectal adenoma risk: a Mendelian randomization study

Background

Previous studies have shown a link between increased dietary intake of arachidonic acid (ARA) and colorectal neoplasms. It has been shown that erythrocyte phospholipid membrane concentrations of ARA are strongly determined by genetic variation. Fatty acid desaturase (FADS) controls the rate limiting step in ARA production, and FADS variant rs174537 has been shown to be responsible for up to 18.6% of the variation seen. To determine if a causal association exists between erythrocyte membrane ARA concentrations and colorectal adenomas, we conducted a Mendelian randomization (MR) analysis using rs174537 as an instrumental variable (IV). MR analysis was chosen because it is less susceptible to bias and confounding.

Patients and methods

A case-control study was performed using the Tennessee Colorectal Polyps Study. Patients were matched on age, gender, race, facility site, and year of colonoscopy. Cases were defined as any colorectal adenoma on colonoscopy (n=909) and controls were polyp free (n=855). A two-stage logistic regression was conducted using rs174537 as the IV with the dependent variable being the presence of a colorectal adenoma on colonoscopy.

Results

Cases were older (59 vs 57 years of age, P<0.0001), and more likely to use alcohol (47.4% vs 19.8%, P=0.001) and to smoke (77.0% vs 66.9%, P<0.0001). There was no statistically significant difference in: age, sex, alcohol use, body mass index (BMI), or NSAID use when stratified by the rs174537 alleles. Genotype was strongly associated with erythrocyte membrane ARA concentrations (P<0.0001). We found no evidence of an association between our IV (rs174537) and colorectal adenomas (P=0.41).

Conclusion

In our MR study increased erythrocyte ARA concentrations were not associated with the risk of colorectal adenomas.

Association of Oral Anticoagulants and Proton Pump Inhibitor Cotherapy With Hospitalization for Upper Gastrointestinal Tract Bleeding

IMPORTANCE

Anticoagulant choice and proton pump inhibitor (PPI) cotherapy could affect the risk of upper gastrointestinal tract bleeding, a frequent and potentially serious complication of oral anticoagulant treatment.

OBJECTIVES

To compare the incidence of hospitalization for upper gastrointestinal tract bleeding in patients using individual anticoagulants with and without PPI cotherapy, and to determine variation according to underlying gastrointestinal bleeding risk.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study in Medicare beneficiaries between January 1, 2011, and September 30, 2015.

EXPOSURES

Apixaban, dabigatran, rivaroxaban, or warfarin with or without PPI cotherapy.

MAIN OUTCOMES AND MEASURES

Hospitalizations for upper gastrointestinal tract bleeding: adjusted incidence and risk difference (RD) per 10 000 person-years of anticoagulant treatment, incidence rate ratios (IRRs).

RESULTS

There were 1 643 123 patients with 1 713 183 new episodes of oral anticoagulant treatment included in the cohort (mean [SD] age, 76.4 [2.4] years, 651 427 person-years of follow-up [56.1%] were for women, and the indication was atrial fibrillation for 870 330 person-years [74.9%]). During 754 389 treatment person-years without PPI cotherapy, the adjusted incidence of hospitalization for upper gastrointestinal tract bleeding (n = 7119) was 115 per 10 000 person-years (95% CI, 112-118). The incidence for rivaroxaban (n = 1278) was 144 per 10 000 person-years (95% CI, 136-152), which was significantly greater than the incidence of hospitalizations for apixaban (n = 279; 73 per 10 000 person-years; IRR, 1.97 [95% CI, 1.73-2.25]; RD, 70.9 [95% CI, 59.1-82.7]), dabigatran (n = 629; 120 per 10 000 person-years; IRR, 1.19 [95% CI, 1.08-1.32]; RD, 23.4 [95% CI, 10.6-36.2]), and warfarin (n = 4933; 113 per 10 000 person-years; IRR, 1.27 [95% CI, 1.19-1.35]; RD, 30.4 [95% CI, 20.3-40.6]). The incidence for apixaban was significantly lower than that for dabigatran (IRR, 0.61 [95% CI, 0.52-0.70]; RD, -47.5 [95% CI,-60.6 to -34.3]) and warfarin (IRR, 0.64 [95% CI, 0.57-0.73]; RD, -40.5 [95% CI, -50.0 to -31.0]). When anticoagulant treatment with PPI cotherapy (264 447 person-years; 76 per 10 000 person-years) was compared with treatment without PPI cotherapy, risk of upper gastrointestinal tract bleeding hospitalizations (n = 2245) was lower overall (IRR, 0.66 [95% CI, 0.62-0.69]) and for apixaban (IRR, 0.66 [95% CI, 0.52-0.85]; RD, -24 [95% CI, -38 to -11]), dabigatran (IRR, 0.49 [95% CI, 0.41-0.59]; RD, -61.1 [95% CI, -74.8 to -47.4]), rivaroxaban (IRR, 0.75 [95% CI, 0.68-0.84]; RD, -35.5 [95% CI, -48.6 to -22.4]), and warfarin (IRR, 0.65 [95% CI, 0.62-0.69]; RD, -39.3 [95% CI, -44.5 to -34.2]).

CONCLUSIONS AND RELEVANCE

Among patients initiating oral anticoagulant treatment, incidence of hospitalization for upper gastrointestinal tract bleeding was the highest in patients prescribed rivaroxaban, and the lowest for patients prescribed apixaban. For each anticoagulant, the incidence of hospitalization for upper gastrointestinal tract bleeding was lower among patients who were receiving PPI cotherapy. These findings may inform assessment of risks and benefits when choosing anticoagulant agents.

Modifiable lifestyle factors associated with risk of sessile serrated polyps, conventional adenomas and hyperplastic polyps

OBJECTIVE

To identify modifiable factors associated with sessile serrated polyps (SSPs) and compare the association of these factors with conventional adenomas (ADs) and hyperplastic polyps (HPs).

DESIGN

We used data from the Tennessee Colorectal Polyp Study, a colonoscopy-based case-control study. Included were 214 SSP cases, 1779 AD cases, 560 HP cases and 3851 polyp-free controls.

RESULTS

Cigarette smoking was associated with increased risk for all polyps and was stronger for SSPs than for ADs (OR 1.74, 95% CI 1.16 to 2.62, for current vs never, ptrend=0.008). Current regular use of non-steroidal anti-inflammatory drugs was associated with a 40% reduction in SSP risk in comparison with never users (OR 0.68, 95% CI 0.48 to 0.96, ptrend=0.03), similar to the association with AD. Red meat intake was strongly associated with SSP risk (OR 2.59, 95% CI 1.41 to 4.74 for highest vs lowest intake, ptrend<0.001) and the association with SSP was stronger than with AD (ptrend=0.003). Obesity, folate intake, fibre intake and fat intake were not associated with SSP risk after adjustment for other factors. Exercise, alcohol use and calcium intake were not associated with risk for SSPs.

CONCLUSIONS

SSPs share some modifiable risk factors for ADs, some of which are more strongly associated with SSPs than ADs. Thus, preventive efforts to reduce risk for ADs may also be applicable to SSPs. Additionally, SSPs have some distinctive risk factors. Future studies should evaluate the preventive strategies for these factors. The findings from this study also contribute to an understanding of the aetiology and biology of SSPs.

Genetic variation in SLC7A2 interacts with calcium and magnesium intakes in modulating the risk of colorectal polyps

Solute carrier family 7, member 2 (SLC7A2) gene encodes a protein called cationic amino acid transporter 2, which mediates the transport of arginine, lysine and ornithine. l-Arginine is necessary for cancer development and progression, including an important role in colorectal cancer pathogenesis. Furthermore, previous studies found that both calcium and magnesium inhibit the transport of arginine. Thus, calcium, magnesium or calcium:magnesium intake ratio may interact with polymorphisms in the SLC7A2 gene in association with colorectal cancer. We conducted a two-phase case-control study within the Tennessee Colorectal Polyps Study. In the first phase, 23 tagging single-nucleotide polymorphisms in the SLC7A2 gene were included for 725 colorectal adenoma cases and 755 controls. In the second phase conducted in an independent set of 607 cases and 2113 controls, we replicated the significant findings in the first phase. We observed that rs2720574 significantly interacted with calcium:magnesium intake ratio in association with odds of adenoma, particularly multiple/advanced adenoma. In the combined analysis, among those with a calcium:magnesium intake ratio below 2.78, individuals who carried GC/CC genotypes demonstrated higher odds of adenoma [OR (95% CI):1.36 (1.11-1.68)] and multiple/advanced adenoma [OR (95% CI): 1.68 (1.28, 2.20)] than those who carried the GG genotype. The P values for interactions between calcium:magnesium intake ratio and rs2720574 were .002 for all adenomas and <.001 for multiple/advanced adenoma. Among those with the GG genotype, a high calcium:magnesium ratio was associated with increased odds of colorectal adenoma [OR (95% CI): 1.73 (1.27-2.36)] and advanced/multiple adenomas [1.62 (1.05-2.50)], whereas among those with the GC/CC genotypes, high calcium:magnesium ratio was related to reduced odds of colorectal adenoma [0.64 (0.42-0.99)] and advanced/multiple adenomas [0.55 (0.31-1.00)].

Interactions between calcium intake and polymorphisms in genes essential for calcium reabsorption and risk of colorectal neoplasia in a two-phase study

The SLC8A1 (solute carrier family 8, member 1) gene, encoding Na⁺ /Ca²⁺ exchanger, is essential in regulating calcium reabsorption and homeostasis. Calcium homeostasis plays a key role in cell proliferation and apoptosis. We hypothesized that polymorphisms in five calcium-regulating genes (SLC8A1, ATP2B1, CALB1, CALB2, and CABP1) interact with calcium intake in relation to the risk of colorectal neoplasia. A two-phase (discovery and replication) study was conducted within the Tennessee Colorectal Polyp Study, including a total of 1275 cases and 2811 controls. In Phase I, we identified six out of 135 SNPs that significantly interacted with calcium intake in relation to adenoma risk. In Phase II, the calcium intake by rs4952490 (SLC8A1) interaction was replicated (P_interaction  = 0.048). We found an inverse association between calcium intake (1000-2000 mg/day) and colorectal adenomas, particularly for multiple/advanced adenomas, among the G-allele carriers but not among homozygous carriers of the common variant (A) in rs4952490. In the joint analysis of SLC8A1, KCNJ1, and SLC12A1 SNPs, carriers of variant alleles in at least two genes and with calcium intake above the DRI (1000 mg/day) were approximately 30-57% less likely to have adenomas than those whose calcium intake was below the DRI. The association was stronger for multiple/advanced adenomas. No association was found among those who did not carry any variant alleles in these genes when calcium intake was below 2500 mg/day. These findings, if confirmed, may provide a new avenue for the personalized prevention of colorectal adenoma and cancer.

Association of Proton Pump Inhibitors With Reduced Risk of Warfarin-Related Serious Upper Gastrointestinal Bleeding

BACKGROUND & AIMS

Proton pump inhibitors (PPIs) might reduce the risk of serious warfarin-related upper gastrointestinal bleeding, but the evidence of their efficacy for this indication is limited. A gastroprotective effect of PPIs would be particularly important for patients who take warfarin with antiplatelet drugs or nonselective nonsteroidal anti-inflammatory drugs (NSAIDs), which further increase the risk of gastrointestinal bleeding.

METHODS

This retrospective cohort study of patients beginning warfarin treatment in Tennessee Medicaid and the 5% National Medicare Sample identified 97,430 new episodes of warfarin treatment with 75,720 person-years of follow-up. The study end points were hospitalizations for upper gastrointestinal bleeding potentially preventable by PPIs and for bleeding at other sites.

RESULTS

Patients who took warfarin without PPI co-therapy had 119 hospitalizations for upper gastrointestinal bleeding per 10,000 person-years of treatment. The risk decreased by 24% among patients who received PPI co-therapy (adjusted hazard ratio [HR], 0.76; 95% confidence interval [CI], 0.63-0.91). There was no significant reduction in the risk of other gastrointestinal bleeding hospitalizations (HR, 1.07; 95% CI, 0.94-1.22) or non-gastrointestinal bleeding hospitalizations (HR, 0.98; 95% CI, 0.84-1.15) in this group. Among patients concurrently using antiplatelet drugs or NSAIDs, those without PPI co-therapy had 284 upper gastrointestinal bleeding hospitalizations per 10,000 person-years of warfarin treatment. The risk decreased by 45% (HR, 0.55; 95% CI, 0.39-0.77) with PPI co-therapy. PPI co-therapy had no significant protective effect for warfarin patients not using antiplatelet drugs or NSAIDs (HR, 0.86; 95% CI, 0.70-1.06). Findings were similar in both study populations.

CONCLUSIONS

In an analysis of patients beginning warfarin treatment in Tennessee Medicaid and the 5% National Medicare Sample, PPI co-therapy was associated with reduced risk of warfarin-related upper gastrointestinal bleeding; the greatest reduction occurred in patients also taking antiplatelet drugs or NSAIDs.

Comparison of biomarker expression between proximal and distal colorectal adenomas: The Tennessee-Indiana Adenoma Recurrence Study

It is unclear if proximal and distal traditional adenomas present with differences in molecular events which contribute to cancer heterogeneity by tumor anatomical subsite. Participants from a colonoscopy-based study (n = 380) were divided into subgroups based on the location of their most advanced adenoma: proximal, distal, or "equivalent both sides." Eight biomarkers in the most advanced adenomas were evaluated by immunohistochemistry (Ki-67, COX-2, TGFβRII, EGFR, β-catenin, cyclin D1, c-Myc) or TUNEL (apoptosis). After an adjustment for pathological features, there were no significant differences between proximal and distal adenomas for any biomarker. Conversely, expression levels did vary by other features, such as their size, villous component, and synchronousness. Large adenomas had higher expression levels of Ki-67(P < 0.001), TGFβRII (P < 0.0001), c-Myc (P < 0.001), and cyclin D1 (P < 0.001) in comparison to small adenomas, and tubulovillous/villous adenomas also were more likely to have similar higher expression levels in comparison to tubular adenomas. Adenoma location is not a major determinant of the expression of these biomarkers outside of other pathological features. This study suggests similarly important roles of Wnt/β-catenin and TGF-β pathways in carcinogenesis in both the proximal and distal colorectum. © 2016 Wiley Periodicals, Inc.

Abstract 802: Genetic polymorphism in SLC7A2 interacts with calcium:magnesium intake ratio in risk of colorectal neoplasia in a two-phase study

Colorectal cancer (CRC) remains the third most common cancer in men and the second in women worldwide; thus, preventive strategies for CRC are critically needed. Solute carrier family 7, member 2 (SLC7A2) gene encodes a protein called cationic amino acid transporter 2, which mediates the transport of arginine, lysine and ornithine. L-arginine is necessary for cancer development and progression, including an important role in CRC pathogenesis. Furthermore, previous studies found both calcium (Ca) and magnesium (Mg) inhibit the transport of arginine. Thus, Ca, Mg or Ca:Mg intake ratio may interact with polymorphisms in the SLC7A2 gene in risk of CRC. To test this hypothesis, we conducted a two-phase case-control study within the Tennessee Colorectal Polyps Study (TCPS) among participants who completed a semi-quantitative 108-item food frequency questionnaire. In the first phase, 23 tagging single-nucleotide polymorphisms (SNPs) in the SLC7A2 gene were analyzed for 725 colorectal adenoma cases and 755 controls. In the second phase conducted in an independent set of 607 cases and 2113 controls, we evaluated for replicationthe significant findings from the first phase. We observed that no SNPs in SLC7A2 were significantly associated with the risk of colorectal adenoma at P &lt; 0.05. However, rs2720574 significantly interacted with Ca:Mg intake ratio in association with adenoma risk, particularly multiple/advanced adenoma in both the first and second phases. In the combined analysis, among those with a Ca:Mg intake ratio below 2.78, individuals who carried GC/CC genotypes were at a higher risk of adenoma [odds ratio (OR, 95% CI) = 1.36(1.11-1.68)] and multiple/advanced adenoma [OR (95% CI) = 1.68(1.28, 2.20)] than those who carried the GG genotype. Among those with the GG genotype, a high Ca:Mg ratio was associated with increased risks of colorectal adenoma (OR (95%CI): 1.73(1.27-2.36)) and advanced/multiple adenomas (1.62(1.05-2.50)) whereas, among those with the GC/CC genotypes, high Ca:Mg ratio was related to reduced risks of colorectal adenoma (0.64(0.42-0.99))and advanced/multiple adenomas (0.55(0.31-1.00)); p(interactions) = 0.002 and 0.0001 for total and advanced/multiple adenomas, respectively. These findings indicate the Ca:Mg ratio, instead of Mg or Ca alone, interacted with SLC7A2 polymorphism in risk of colorectal neoplasia.

Citation Format: Xiangzhu Zhu, Pin Sun, Martha J. Shrubsole, Reid M. Ness, Elizabeth A. Hibler, Qiuyin Cai, Jirong Long, Zhi Chen, Guoliang Li, Lifang Hou, Walter E. Smalley, Todd L. Edwards, Edward Giovannucci, Wei Zheng, Qi Dai. Genetic polymorphism in SLC7A2 interacts with calcium:magnesium intake ratio in risk of colorectal neoplasia in a two-phase study. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 802.

Calcium/magnesium intake ratio, but not magnesium intake, interacts with genetic polymorphism in relation to colorectal neoplasia in a two-phase study

Some studies suggest that the calcium to magnesium ratio intakes modify the associations of calcium or magnesium with risk of colorectal adenoma, adenoma recurrence, and cancer. Parathyroid hormone (PTH) plays a key role in the regulation of homeostasis for both calcium and magnesium. We hypothesized that polymorphisms in PTH and 13 other genes may modify the association between the calcium/magnesium intake ratio and colorectal neoplasia risk. We conducted a two-phase study including 1336 cases and 2891 controls from the Tennessee Colorectal Polyp Study. In Phase I, we identified 19 SNPs that significantly interacted with the calcium/magnesium intake ratio in adenoma risk. In Phase II, rs11022858 in PTH was replicated. In combined analysis of phases I and II, we found high calcium/magnesium intake ratio tended to be associated with a reduced risk of colorectal adenoma (P for trend, 0.040) among those who carried the TT genotype in rs11022858. In stratified analyses, calcium intake (≥ 1000 mg/d) was significantly associated with 64% reduced adenoma risk (OR = 0.36 (95% CI : 0.18-0.74)) among those homozygous for the minor allele (TT genotype) (P for trend, 0.012), but not associated with risk in other genotypes (CC/TC). Conversely, we found that highest magnesium intake was significantly associated with 27% reduced risk (OR = 0.73 (95% CI : 0.54-0.97)) of colorectal adenoma (P for trend, 0.026) among those who possessed the CC/TC genotypes, particularly among those with the TC genotype, whereas magnesium intake was not linked to risk among those with the TT genotype. These findings, if confirmed, will help for the development of personalized prevention strategies for colorectal cancer. © 2015 Wiley Periodicals, Inc.

Evaluation of pro-inflammatory markers plasma C-reactive protein and urinary prostaglandin-E2 metabolite in colorectal adenoma risk

C-reactive protein (CRP) is a pro-inflammatory protein with potential as a biomarker in predicting colon cancer risk. However, little is known regarding its association with risk of colorectal adenomas, particularly by subtypes. We conducted a colonoscopy-based matched case-control study to assess whether elevated plasma CRP levels may be associated with colorectal adenoma risk and further whether this association may be modified by urinary prostaglandin E2 metabolite (PGE-M), a biomarker of systemic prostaglandin E2 production. Included in the study were 226 cases with a single small tubular adenoma, 198 cases with multiple small tubular adenomas, 283 cases with at least one advanced adenoma, and 395 polyp-free controls. No apparent association between CRP level and risk of single small tubular adenomas was found (ptrend  = 0.59). A dose-response relationship with CRP level was observed for risk of either multiple small tubular adenomas (OR = 2.01, 95%CI = 1.10-3.68 for the highest versus lowest tertile comparison; ptrend   = 0.03) or advanced adenomas (OR = 1.81, 95%CI = 1.10-2.96 for the highest versus lowest tertile comparison; ptrend  = 0.02). In a joint analysis of CRP level and PGE-M, risk of multiple or advanced adenoma was greatest among those with highest levels of both CRP and PGE-M in comparison to those with low CRP and low PGE-M (OR = 3.72, 95%CI = 1.49-9.72). Our results suggest that elevated CRP, particularly in the context of concurrent elevated PGE-M, may be a biomarker of multiple or advanced adenoma risk in a screening age population. © 2015 Wiley Periodicals, Inc.

Aspects of dietary carbohydrate intake are not related to risk of colorectal polyps in the Tennessee Colorectal Polyp Study

PURPOSE

High digestible carbohydrate intakes can induce hyperglycemia and hyperinsulinemia and collectively have been implicated in colorectal tumor development. Our aim was to explore the association between aspects of dietary carbohydrate intake and risk of colorectal adenomas and hyperplastic polyps in a large case-control study.

METHODS

Colorectal polyp cases (n = 1,315 adenomas only, n = 566 hyperplastic polyps only and n = 394 both) and controls (n = 3,184) undergoing colonoscopy were recruited between 2003 and 2010 in Nashville, Tennessee, USA. Dietary intakes were estimated by a 108-item food frequency questionnaire. Unconditional logistic regression analysis was applied to determine odds ratios (OR) and corresponding 95 % confidence intervals (CI) for colorectal polyps according to dietary carbohydrate intakes, after adjustment for potential confounders.

RESULTS

No significant associations were detected for risk of colorectal adenomas when comparing the highest versus lowest quartiles of intake for total sugars (OR 1.03; 95 % CI 0.84-1.26), starch (OR 1.01; 95 % CI 0.81-1.26), total or available carbohydrate intakes. Similar null associations were observed between dietary carbohydrate intakes and risk of hyperplastic polyps, or concurrent adenomas and hyperplastic polyps.

CONCLUSION

In this US population, digestible carbohydrate intakes were not associated with risk of colorectal polyps, suggesting that dietary carbohydrate does not have an etiological role in the early stages of colorectal carcinogenesis.

Plasma lipid levels and colorectal adenoma risk

PURPOSE

Abnormalities in lipid levels have been associated with colorectal neoplasm risk; however, few studies have adjusted for use of cholesterol-lowering medications. The objective of this study was to determine the association of plasma lipid levels with adenoma risk while accounting for statin medication use.

METHODS

We included 254 subjects with advanced adenoma, 246 with single small adenoma, 179 with multiple small adenoma cases, and 403 control participants in the Tennessee Colorectal Polyp Study who also had plasma lipid measurements performed. Data on the use of statin medications were available for 83.4% of these participants. The association between plasma lipids and adenoma risk was evaluated using logistic regression models.

RESULTS

Participants in the highest quartile of HDL cholesterol (range 52-106 mg/dl) had an adjusted odds ratio of 0.49 (95% CI 0.23, 1.07), 0.35 (95% CI 0.13, 0.91), and 0.22 (95% CI 0.09, 0.54) for single small, multiple small, and advanced adenomas compared to the lowest quartile (range 12-34 mg/dl), respectively. Participants with the highest quartile of triglyceride levels (range 178-721 mg/dl) had an adjusted odds ratio of 2.40 (95% CI 1.26, 4.55), 1.67 (95% CI 0.66, 4.23), and 2.79 (95% CI 1.25, 6.23) for single small, multiple small, and advanced adenoma, respectively, compared to the lowest quartile (range 40-84 mg/dl). When restricted to individuals with known statin medication use, adjusting for statin use did not appreciably affect these results.

CONCLUSION

We found a direct association between triglyceride plasma levels and an inverse association between plasma HDL cholesterol levels and adenoma risk. Both effects were not appreciably changed when accounting for the regular use of statin medication.

Calcium intake and ion transporter genetic polymorphisms interact in human colorectal neoplasia risk in a 2-phase study

BACKGROUND

The kidney-specific sodium-potassium-chloride cotransporter (NKCC2) protein encoded by solute carrier family 12 member 1 (SLC12A1) is the direct downstream effector of the inward-rectifier potassium channel (ROMK) encoded by potassium inwardly-rectifying channel, subfamily J, member 1 (KCNJ1), both of which are critical for calcium reabsorption in the kidney.

OBJECTIVE

We hypothesized that polymorphisms in KCNJ1, SLC12A1, and 7 other genes may modify the association between calcium intake and colorectal neoplasia risk.

METHODS

We conducted a 2-phase study in 1336 cases and 2891 controls from the Tennessee Colorectal Polyp Study.

RESULTS

In phase I, we identified 5 single-nucleotide polymorphisms (SNPs) that significantly interacted with calcium intake in adenoma risk. In phase II, rs2855798 in KCNJ1 was replicated. In combined analysis of phases I and II, the P values for interactions between calcium intake and rs2855798 were 1 × 10(-4) for all adenoma and 5 × 10(-3) for multiple/advanced adenoma. The highest calcium intake was not associated with risk among those with no variant allele but was significantly associated with a 41% reduced adenoma risk among those who carried at least 1 variant allele in KCNJ1. The corresponding reduction in risk of multiple or advanced adenomas was 52% among those with at least 1 variant allele. The P values for interactions between calcium intake and combined SNPs from the KCNJ1 and SLC12A1 genes were 7.5 × 10(-5) for adenoma and 9.9 × 10(-5) for multiple/advanced adenoma. The highest calcium intake was not associated with risk among those with nonvariant alleles in 2 genes but was significantly associated with a 34% reduced adenoma risk among those who carried a variant allele in 1 of the genes. The corresponding reduction in risk of multiple or advanced adenomas was 64% among those with variant alleles in both genes.

CONCLUSION

These findings, if confirmed, will be critical for the development of personalized prevention strategies for colorectal cancer.

Abstract 2196: Two-phase study of PTH polymorphisms, calcium, magnesium and colorectal adenoma risk

Background: The findings on the associations between intakes of calcium and magnesium with risks of colorectal adenoma and cancer have not been consistent. Previous studies identified substantial inter-person variability in calcium absorption (10-70%). The differences in calcium absorption persist over time and only a small portion of cases can be explained by known factors. Calcium competes with magnesium in many biological activities such as (re)absorption. The polymorphisms in genes related to calcium and magnesium may modify the associations between intakes of calcium and magnesium and risk of colorectal cancer and adenoma. Parathyroid hormone (PTH) is a critical hormone in the regulation of calcium concentration and magnesium in extracellular fluid and plays a key role in (re)absorption of both calcium and magnesium in the gut and kidney.

Objectives: We hypothesize that common variants in PTH may modify the associations between calcium and magnesium intake or calcium/magnesium ratio and risk of colorectal adenoma risk.

Methods: Included were participants of the Tennessee Colorectal Polyp Study (TCPS), a colonoscopy-based case control study conducted in Nashville, TN. In the Phase I study, genotyping was performed using the Affymetrix Human Mapping 500K array in 728 colorectal adenoma cases and 757 controls and 3 tagging single-nucleotide polymorphisms (SNPs) in the PTH gene were evaluated. SNPs identified as significant in phase I were genotyped in Phase II in an independent set (546 cases and 2062 controls). Dietary nutrient intakes were obtained from a food frequency questionnaire. Multivariate unconditional logistic regression models were used to estimate the odds ratios and 95% confidence intervals for each SNP. Multiplicative interactions were evaluated for gene-diet interactions using likelihood ratio tests.

Results: In Phase I of the study, we identified 2 SNPs that significantly interacted with calcium to magnesium (Ca/Mg) intake ratio in association with adenoma risk. In an independent set (Phase II), one of two gene-Ca/Mg ratio interactions was replicated. In the combined analysis, we found that intakes of calcium and magnesium were related to a reduced risk of colorectal adenoma. However, in stratified analysis, magnesium intake was only associated with a reduced risk of adenoma among those with the TC/CC genotype (p for trend, 0.03). Magnesium intake≥320 mg/day was linked to about 40% reduction in risk among those with the TC genotype. On the other hand, calcium intake was only related to a reduced risk for those who carry the TC/TT genotype (p for tend, 0.02). Calcium intake≥1000 mg/day was associated with an over 40% reduction in risk of colorectal adenoma among the TT group.

Conclusions: Intakes of calcium and magnesium are linked to reduced risk of adenoma for subsets of populations with different genotypes.

Citation Format: Zhu Xiangzhu, Martha J. Shrubsole, Reid M. Ness, Qiuyin Cai, Walter E. Smalley, Todd L. Edwards, Edward Giovannucci, Wei Zheng, Qi Dai. Two-phase study of PTH polymorphisms, calcium, magnesium and colorectal adenoma risk. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2196. doi:10.1158/1538-7445.AM2014-2196

Associations between dietary fiber and colorectal polyp risk differ by polyp type and smoking status

The association of dietary fiber intake with colorectal cancer risk is established. However, the association may differ between cigarette smokers and nonsmokers. We evaluated this hypothesis in a large colonoscopy-based case-control study. Dietary fiber intakes were estimated by self-administered food frequency questionnaire. Unconditional logistic regression analysis was used to estimate ORs and 95% CIs with adjustment for potential confounders. Analysis also was stratified by cigarette smoking and sex. High dietary fiber intake was associated with reduced risk of colorectal polyps (P-trend = 0.003). This association was found to be stronger among cigarette smokers (P-trend = 0.006) than nonsmokers (P-trend = 0.21), although the test for multiplicative interaction was not statistically significant (P = 0.11). This pattern of association was more evident for high-risk adenomatous polyps (ADs), defined as advanced or multiple ADs (P-interaction smoking and dietary fiber intake = 0.09). Among cigarette smokers who smoked ≥23 y, a 38% reduced risk of high-risk ADs was found to be associated with high intake of dietary fiber compared with those in the lowest quartile fiber intake group (P-trend = 0.004). No inverse association with dietary fiber intake was observed for low-risk ADs, defined as single nonadvanced ADs. Cigarette smoking may modify the association of dietary fiber intake with the risk of colorectal polyps, especially high-risk ADs, a well-established precursor of colorectal cancer.

Abstract 4832: High calcium reduces multiple or advanced colorectal adenoma risk by nearly 90% among those with variant alleles in two critical genes in calcium reabsorption

Despite the rapidly increasing use of colonoscopy, colorectal cancer still remains the 2nd most common cause of cancer death in the United States. Most of these colorectal cancers arise from adenomas. High calcium consumption has been linked to reduced risks of colorectal adenoma and cancer. However, results from a large clinical trial conducted in the general population were not consistent from those conducted among colorectal adenoma patients. Adenoma patients have a lower intake of calcium than general population. Furthermore, previous studies indicate there is substantial inter-individual variation in the ability to (re)absorb calcium, which is mostly attributed to genetic variation. Thus, we hypothesized that some of the inconsistency in previous studies was due to interactions between calcium and genetic polymorphisms involved in calcium homeostasis. In an NIH R01 project, we conducted a two- phase study to evaluate whether polymorphisms in KCNJ1 and 13 other genes modified the associations between calcium intake and risk of colorectal adenoma. Included in the study were 1818 cases and 3992 controls identified from the Tennessee Colorectal Polyp Study (TCPS), a colonoscopy-based case control study conducted in Nashville, TN. We identified in Phase 1 and replicated in Phase 2 that two polymorphisms in two genes (i.e. one SNP in each gene) significantly modified the associations between calcium intake and colorectal adenoma risk. One gene is potassium inwardly-rectifying channel, subfamily J, member 1 (KCNJ1), which etiologically leads to hereditary familial diseases with impairments in reabsorption for calcium. The p for interaction with the SNP in the KCNJ1 gene remained statistically significant after Bonferroni correction for multiple comparisons (all SNPs in 14 genes). In the combined analysis of these two genes, we found 52% of the study population carry at least one variant allele in one of two genes while 13% of the population carry variant alleles in both genes. We found among those with zero variant alleles in two genes, the highest tertile of calcium intake was not associated with adenoma risk with an OR (95% CI) of 1.06(0.65-1.72). Highest calcium intake tertile was significantly associated with a 39% reduced adenoma risk among those who carry variant allele in one gene (p for trend, 0.046), and with a 69% reduced risk among those with alleles in both genes (p for trend, 0.039). The corresponding reduction in risk with advanced or multiple adenomas increased to 89% (95%CI: 41%-98%) among those with variant alleles in both genes (p for interaction, 5.5×10−5). In summary, high intake of calcium may only protect against colorectal carcinogenesis among those who carry variant alleles in two genes, particularly for those who carry variant alleles in both genes.

Citation Format: Xiangzhu Zhu, Martha J. Shrubsole, Reid M. Ness, Qiuyin Cai, Jirong Long, Zhi Chen, Ji Liang, Guoliang Li, Walter E. Smalley, Todd L. Edwards, Edward Giovannucci, Wei Zheng, Qi Dai. High calcium reduces multiple or advanced colorectal adenoma risk by nearly 90% among those with variant alleles in two critical genes in calcium reabsorption. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4832. doi:10.1158/1538-7445.AM2013-4832

Interaction of cigarette smoking and carcinogen-metabolizing polymorphisms in the risk of colorectal polyps

The causal role of cigarette smoking in the risk of colorectal neoplasm has been suggested but not established. In a case-control study including 2060 colorectal polyp patients and 3336 polyp-free controls, we evaluated 21 functional genetic variants to construct a tobacco-carcinogen-metabolizing genetic risk score. Data regarding cigarette smoking were obtained through telephone interviews. Cigarette smoking was associated with an elevated risk of both adenomas and hyperplastic polyps. The association with smoking was stronger in participants with a high carcinogen-metabolizing risk score than those with a low risk score. Smoking 30 or more cigarettes per day was associated with a 1.7-fold elevated risk of any polyps (95% confidence interval = 1.3-2.2) among those with a low genetic risk score and 2.9-fold elevated risk (95% confidence interval = 1.8-4.8) among those with a high genetic risk score (P interaction = 0.025). A similar pattern of interaction was observed in analyses conducted separately for those with adenomas only (P interaction = 0.039) and hyperplastic polyps only (P interaction = 0.024). Interaction between carcinogen-metabolizing genetic risk and cigarette smoking was found in relation to high-risk adenomas (P interaction = 0.010) but not low-risk adenomas (P interaction = 0.791). No apparent interaction was found for duration of smoking. This study shows that the association between cigarette smoking and colorectal polyp risk is modified by tobacco-carcinogen-metabolizing polymorphisms, providing support for a causal role of cigarette smoking in the etiology of colorectal tumors.

Lifestyle factors and their combined impact on the risk of colorectal polyps

Understanding patterns of shared and type-specific etiologies for colorectal polyps may provide insights into colorectal carcinogenesis. The authors present the first systematic comparison of risk factors by colorectal polyp type in a large colonoscopy-based case-control study of 3,764 polyp-free controls and 2,543 polyp patients, including 1,444 cases with adenomas only, 662 cases with hyperplastic polyps (HPPs) only, and 437 cases with synchronous HPPs and adenomas. Surveys were completed to obtain information on usual dietary intake and other lifestyle factors. Six lifestyle factors, including cigarette smoking, obesity, no regular use of nonsteroidal anti-inflammatory drugs, high intake of red meat, low intake of fiber, and low intake of calcium, were found to be independently associated with the risk of polyps. The risk of polyps increased progressively with an increasing number of adverse lifestyle factors. Compared with participants with no or only 1 risk factor, odds ratios for those with 5 to 6 risk factors were 2.72 (95% confidence interval: 1.94, 3.79) for adenoma only, 4.12 (95% confidence interval: 2.78, 6.09) for HPPs only, and 9.03 (95% confidence interval: 5.69, 14.34) for synchronous HPPs and adenomas. This study provides strong evidence that lifestyle modification is important for the prevention of colorectal polyps, especially advanced and multiple adenomas, which are established precursors of colorectal cancer.

Using gene-environment interaction analyses to clarify the role of well-done meat and heterocyclic amine exposure in the etiology of colorectal polyps

BACKGROUND

The role of well-done meat intake and meat-derived mutagen heterocyclic amine (HCA) exposure in the risk of colorectal neoplasm has been suggested but not yet established.

OBJECTIVE

With the use of gene-environment interaction analyses, we sought to clarify the association of HCA exposure with colorectal polyp risk.

DESIGN

In a case-control study including 2057 colorectal polyp patients and 3329 controls, we evaluated 16 functional genetic variants to construct an HCA-metabolizing score. To derive dietary HCA-exposure amount, data were collected regarding dietary intake of meat by cooking method and degree of doneness.

RESULTS

A 2-fold elevated risk associated with high red meat intake was found for colorectal polyps or adenomas in subjects with a high HCA-metabolizing risk score, whereas the risk was 1.3- to 1.4-fold among those with a low risk score (P-interaction ≤ 0.05). The interaction was stronger for the risk of advanced or multiple adenomas, in which an OR of 2.8 (95% CI: 1.8, 4.6) was observed for those with both a high HCA-risk score and high red meat intake (P-interaction = 0.01). No statistically significant interaction was found in analyses that used specific HCA exposure derived from dietary data.

CONCLUSION

High red meat intake is associated with an elevated risk of colorectal polyps, and this association may be synergistically modified by genetic factors involved in HCA metabolism.

Association of genetic variants for colorectal cancer differs by subtypes of polyps in the colorectum

Most colorectal cancers originate from polyps, however, only a small proportion of polyps progress to carcinomas. Genome-wide association studies have identified multiple single-nucleotide polymorphisms (SNPs) in relation to colorectal cancer. Using these genetic risk variants, we evaluated whether colorectal cancer genetic factors may determine certain polyp phenotypes with different malignant potential. We analyzed 20 SNPs in 15 colorectal cancer susceptibility loci in a case-control study including 2473 cases (1831 with adenomas and 642 with hyperplastic polyps only) and 4019 controls. These patients were recruited from participants who received colonoscopy at two major hospitals in Nashville. A weighted genetic risk score (wGRS) was created to measure the cumulative association of multiple SNPs with polyp subtypes. Thirteen SNPs in 10 loci showed a statistically significant (P < 0.05, n = 9) or marginally significant (P < 0.10, n = 4) association with the risk of adenomas or hyperplastic polyps in the same direction as reported previously for colorectal cancer. A dose-response relation was observed between the wGRS and adenoma risk [per-allele odds ratio (OR) = 1.15, 95 confidence interval (CI): 1.10-1.20, P (trend) = 7.3×10(-10)], with the association stronger for advanced than non-advanced adenomas (P (heterogeneity) = 0.038), for multiple adenomas than a single adenoma (P (heterogeneity) = 0.039), and for proximal than distal adenomas (P (heterogeneity) = 0.038) and for adenomas diagnosed at younger than older age (P (heterogeneity) = 0.031). A similar, but weak association between the wGRS and hyperplastic polyps was also observed (OR = 1.11, 95% CI: 1.04-1.18, P (trend) = 0.002). These findings suggest that genetic factors play a significant role in the development of polyps with different malignant potential.

Abstract 4817: Using the Mendelian randomization approach to clarify the role of well-done meat and heterocyclic amine exposure in the etiology of colorectal polyps

Background: High red meat intake and meat-derived mutagen heterocyclic amines (HCAs) exposure have been linked to the risk of colorectal polyps and cancer. HCAs are activated and detoxified by a group of carcinogen metabolizing enzymes. Internal exposure dose to these carcinogens is determined by both external exposure and genetic polymorphisms in genes encoding these enzymes, providing a unique opportunity to conduct a Mendelian randomization analysis to reduce bias associated with observational epidemiological studies. Methods: In a colonoscopy-based case-control study, we recruited 5,386 participants, including 2,057 patients with colorectal polyps, and 3,329 polyp-free controls. Twenty single nucleotide polymorphisms (SNPs) were analyzed to construct a HCA metabolizing score. Data on dietary intake of meat by cooking methods and doneness level were obtained through telephone interviews to derive dietary HCA exposure level. Interactions between HCA metabolizing score and dietary exposure variables were evaluated using multivariate unconditional logistic regression models to derive odds ratios (ORs) and 95% confidence intervals (CIs). Results: HCA metabolizing score was unrelated to polyp risk among those with a low intake of total meat or red meat and low dietary HCA exposure. These dietary variables also tended to not be associated with polyp risk among those with a low HCA metabolizing score. Risks of polyps associated with meat intake and HCA exposure, however, were elevated among those with a high risk HCA metabolizing score. The interactions between dietary meat exposures and HCA metabolizing score were statistically significant for most of the analyses (P α0.05). Participants with the highest meat intake and HCA exposure level and a high risk HCA metabolizing score had a 30% to 40% elevated risk of developing any polyps and 60% to 80% elevated risk of developing advanced or multiple adenomas. Conclusions: Dietary meat intake and dietary exposure to HCAs is associated with an elevated risk of colorectal polyps, and this association is modified by genetic polymorphisms in HCA metabolizing enzymes. This study provides strong evidence supporting a causal role of HCA exposure in the etiology of colorectal tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4817. doi:1538-7445.AM2012-4817

Abstract 1674: Two phase study of KCNJ1 polymorphisms, calcium, magnesium and colorectal adenoma risk, results from the Tennessee Colorectal Polyp Study

Background: Previous studies generated inconsistent results on the associations between intakes of calcium and magnesium with risk of colorectal adenoma and cancer. It is possible that some of the inconsistency is due to a modifying effect by genetic polymorphisms involved in calcium and magnesium homeostasis. The KCNJ1 gene encodes the Inward-rectifier potassium channel (ROMK). ROMK plays an essential role in the homeostasis of potassium, which is critical for the reabsorption of calcium and magnesium. Objectives: We hypothesize that common variants in KCNJ1 may modify the associations between intakes of calcium and/or magnesium and risk of colorectal adenoma risk. Methods: Included were participants of the Tennessee Colorectal Polyp Study (TCPS), a colonoscopy-based case control study conducted in Nashville, TN. In the phase I study, genotyping was performed using the Affymetrix Human Mapping 500K array set in 958 colorectal adenoma cases and 909 controls and 13 tagging single-nucleotide polymorphisms (SNPs) in the KCNJ1 gene were evaluated. SNPs identified as significant in phase I were genotyped in phase II in an independent set (860 cases and 3083 controls). Results: In phase I, 1 tagging SNP was significantly associated with adenoma risk and 8 SNPs were interacted significantly with calcium or magnesium intake in risk of colorectal adenoma. In phase II, only 1 of the 9 SNPs significantly interacted with calcium and magnesium intakes in relation to colorectal adenoma although the genotype per se was not directly associated with the risk. In combined analysis, the p value for the interaction between the SNP and calcium intake was 0.00015 and it remained statistically significant after Bonferroni correction for multiple comparisons. In stratified analyses by levels of calcium and magnesium (above or below RDA levels), we found adenoma risk significantly increased for those who with at least 1 variant allele and whose intake levels of calcium and magnesium were below the RDA levels, with ORs (95% CI) of 1.35 (1.10, 1.67) and 1.43 (1.08, 1.89) respectively, compared to those who did not possess the variant allele. The corresponding ORs (95% CI) increased to 1.84 (1.33, 2.53) and 2.30 (1.53, 3.46), respectively, multiple adenomas versus controls. Conclusions: In this two-stage analysis, we found no overall association of adenoma with KCNJ1 genotype. However, common KCNJ1 variants significantly interacted with intakes of calcium and magnesium in risk of colorectal adenoma, particular for multiple adenomas.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1674. doi:1538-7445.AM2012-1674

Abstract 4478: Erythrocyte magnesium, TRPM7 Thr1482Ile polymorphism, and colorectal adenoma risk

Background: Several epidemiologic studies indicate high intake of magnesium may be related to a reduced risk of colorectal cancer and adenoma. However, results from previous studies have not been consistent. We reported previously the inverse association between dietary magnesium and risk of colorectal adenoma primarily appeared in those who carried at least one Thr1482Ile allele in the transient receptor potential melastatin 7 (TRPM7) gene, which plays an essential role in the homeostasis and sensing of magnesium. Serum magnesium is regulated in a narrow range and previous studies indicate erythrocyte magnesium may be a better biomarker of body magnesium status than serum magnesium. Objective: To examine whether erythrocyte magnesium is associated with adenoma risk and if the association is modified by the Thr1482Ile polymorphism. Design: Included in this nested case-control study were 341adenoma cases and 343 matched polyp-free controls from the Tennessee Colorectal Polyp Study (TCPS), a colonoscopy-based case control study conducted in Nashville, TN. Total erythrocyte magnesium levels were measured using flame atomic absorption spectroscopy. Genotyping assay was performed using the TaqMan OpenArray platform. Multivariate logistic regression models were used to estimate the odds ratio and 95% confidence intervals as a measure of the strength of associations. The association of each genotype with colorectal adenoma risk was evaluated under dominant, recessive and additive models, respectively. Results: Overall erythrocyte magnesium level was not associated with risk of colorectal adenoma. However, erythrocyte magnesium tended to be associated with a reduced risk among those who carried at least one Thr1482Ile allele in the TRPM7 gene (rs8042919), particularly after adjusting for potential confounding factors, such as age, assay batch, family history, and dietary intakes of magnesium and fiber with the ORs (95% CI) of 0.19 (0.05, 0.76) and 0.34 (0.08, 1.49) respectively for the medium and highest tertile of erythrocyte magnesium levels versus the lowest tertile. In addition, among people with erythrocyte magnesium below the median, we found people who carried at least one 1482Ile allele tended to be at an elevated risk of adenoma with an OR (95% CI) of 1.7(0.85, 3.43), compared to those who did not carry the polymorphism; while the corresponding OR (95% CI) was 0.94 (0.49, 1.81) for those who carried at least one Thr1482Ile allele if erythrocyte magnesium was above the median. Conclusions: Our findings indicate the TRPM7 Thr1482Ile polymorphism may interact with erythrocyte magnesium levels in relation to colorectal adenoma risk even after controlling for dietary intake of magnesium.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4478. doi:1538-7445.AM2012-4478

Dietary intake of PUFAs and colorectal polyp risk

BACKGROUND

Marine-derived n-3 (omega-3) PUFAs may reduce risk of developing colorectal cancer; however, few studies have investigated the association of n-3 PUFA intakes on colorectal polyp risk.

OBJECTIVE

The objective of this study was to examine the associations of dietary PUFA intake on risk of colorectal adenomatous and hyperplastic polyps.

DESIGN

This was a colonoscopy-based case-control study that included 3166 polyp-free control subjects, 1597 adenomatous polyp cases, and 544 hyperplastic polyp cases. Dietary PUFA intake was calculated from food-frequency questionnaires and tested for association by using unconditional logistic regression. The urinary prostaglandin E(2) metabolite, which is a biomarker of prostaglandin E(2) production, was measured in 896 participants by using liquid chromatography and tandem mass spectrometry.

RESULTS

n-6 PUFAs were not associated with adenomatous or hyperplastic polyps in either men or women. Marine-derived n-3 PUFAs were associated with reduced risk of colorectal adenomas in women only, with an adjusted OR of 0.67 (95% CI: 0.47, 0.97) for the highest quintile of intake compared with the lowest quintile of intake (P-trend = 0.01). Dietary intake of α-linolenic acid was associated with an increased risk of hyperplastic polyps in men (P-trend = 0.03), which was not seen in women. In women, but not in men, dietary intake of marine-derived n-3 PUFAs was negatively correlated with urinary prostaglandin E(2) production (r = -0.18; P = 0.002).

CONCLUSION

Higher intakes of marine-derived n-3 PUFAs are associated with lower risk of adenomatous polyps in women, and the association may be mediated in part through a reduction in the production of prostaglandin E(2). This trial was registered at clinicaltrials.gov as NCT00625066.

Urinary prostaglandin E2 metabolite and risk for colorectal adenoma

COX-2 is upregulated in most colorectal cancers. Most of the COX-2 tumor-inducing effects are believed to be mediated through overproduction of prostaglandin E(2) (PGE(2)), which can be measured using a urinary metabolite of PGE(2), PGE-M. Urinary PGE-M was assessed in a case-control study of colorectal adenoma. Included in the analysis were 224 cases with at least one advanced adenoma, 152 cases with multiple small tubular adenomas, 300 cases with only a single small tubular adenoma, and 364 polyp-free controls. There were no statistical differences in PGE-M levels between controls and cases with a single small tubular adenoma. However, cases with either an advanced adenoma or multiple small tubular adenomas had more than 25% higher levels of PGE-M than controls. Participants with the highest quartile level of PGE-M were approximately 2.5-fold more likely to have advanced or multiple small tubular adenoma in comparison with those with the lowest level of PGE-M [OR = 2.53; 95% confidence interval (CI), 1.54-4.14; P(trend) < 0.001]. The association was strongest among women. PGE-M level was associated with increased risk for multiple or advanced adenoma but not single small adenoma. Our study suggests that PGE-M may be a useful risk marker for assessing the risk of harboring clinically more important versus less important colorectal neoplasia.

Association of meat intake and meat-derived mutagen exposure with the risk of colorectal polyps by histologic type

The association of meat intake and meat-derived mutagens with colorectal tumor risk remains unclear. We evaluated this hypothesis in a large colonoscopy-based case-control study. Included in the study were 2,543 patients with polyp [(1,881 with adenomas and 622 with hyperplastic polyp (HPP)] and 3,764 polyp-free controls. Surveys obtained information about meat intake by cooking methods and doneness levels plus other suspected or known risk factors for colorectal tumors. Unconditional logistic regression was used to derive ORs after adjusting for potential confounders. High intake of red meat and processed meat (P(trend) < 0.05), particularly red meat cooked using high-temperature cooking methods (P(trend) ≤ 0.01), was associated with an elevated risk for colorectal polyps. A significant positive association between exposures to meat-derived heterocyclic amines (HCA) and risk of polyps was found for both adenomas and HPPs. Furthermore, the positive association with red meat intake and HCA exposure was stronger for multiple adenomas than for single adenoma as well as for serrated than for nonserrated adenomas. This study supports a role for red meat and meat-derived mutagen exposure in the development of colorectal tumor.

Nonsteroidal anti-inflammatory drug use and risk of adenomatous and hyperplastic polyps

Adenomatous polyps are known precursor lesions for colorectal cancer and some hyperplastic polyps also have malignant potential. The use of aspirin and nonsteroidal anti-inflammatory drugs (NSAID) is associated with a reduced risk of adenomatous polyps; however, less evidence exists with regard to NSAID use and hyperplastic polyp risk. We conducted a colonoscopy-based case-control study including 2,028 polyp cases (1,529 adenomatous and 499 hyperplastic) and 3,431 polyp-free controls. Multivariate logistic regression models were constructed to derived adjusted ORs and 95% CIs as the measure of the association between NSAID use and polyp risk. Use of baby aspirin, regular aspirin, and nonaspirin NSAIDs, were associated with a reduced risk of adenomatous polyps (OR = 0.79, 95% CI: 0.66-0.93, OR = 0.73, 95% CI: 0.58-0.90, and OR = 0.67, 95% CI: 0.53-0.86, respectively). Baby aspirin was also associated with a reduced risk of hyperplastic polyps (OR = 0.74, 0.56-0.97). Although a dose response was seen with adenoma risk and regular use of any NSAIDs (less than 7 doses per week, 7 doses per week, and greater than 7 doses per week), a dose response was not seen with hyperplastic polyps. We found no evidence of interaction between NSAID dose and duration and polyp risk. The use of any NSAID regardless of type was associated with a reduced risk of adenomatous polyps; however, regular aspirin and COX-2 inhibitors use was not associated with hyperplastic polyp risk.

Abstract 3763: Calcium intake, CABP1 polymorphisms, and the risk of colorectal adenoma: Results from Tennessee Colorectal Polyp Study

Background: High calcium consumption may confer a reduced risk of colorectal adenoma and cancer. This effect could differ by polymorphisms in the genes involved in calcium regulation. The calcium binding protein 1(CABP1) gene encodes a calbindin-D9k protein, an important component of calcium mediated cellular signal transduction. CABP1 express primarily in intestine, and increased levels of Calbindin-D9k in intestine were found to be correlated with calcium hyperabsorption. A recent study found that deletion of CABP1 and another gene had a significant effect on calcium processing under calcium-deficient conditions. These findings suggest the variations in CABP1 expression in intestine may explain some of the variability in calcium absorption. However, so far no study has evaluated genetic variations in CABP1 with the risk of colorectal adenoma.

Objectives: In the current study, we first screened whether CABP1 variants or their interactions with calcium intake were associated with urinary calcium among 256 normal controls. Further, single-nucleotide polymorphisms (SNPs) were evaluated for their independent association and interactions with calcium intake in relation to colorectal adenoma risk.

Methods: Included in the study were 958 adenoma cases and 909 controls from the Tennessee Colorectal Polyp Study (TCPS), an ongoing colonoscopy-based case-control study conducted in Nashville, TN. Genotyping was performed using the Affymetrix Human Mapping 500K array set. Seven tagging SNPs in CABP1 were analyzed. Linear regression models were used to estimate the association between genotypes and urinary calcium level. Multivariate unconditional logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI). Multiplicative interactions for gene-diet interactions were evaluated in logistic regression models by using likelihood ratio tests.

Results: Although no SNPs were observed to be associated with urinary calcium levels, one SNP (rs7956304) was found to be significantly associated with risk of adenoma. In comparison to participants with the GG genotype, participants with GA had higher risk of colorectal adenoma (OR=1.29, 95% CI 1.03-1.61, P=0.027), while participants with the AA genotype had no appreciable difference in risk (OR=0.82, 95% CI 0.50-1.35, P=0.428). This SNP was not observed to interact with calcium intake.

Conclusions: These findings suggest that genetic variations in CABP1 may affect the risk of colorectal adenoma. To the best of our knowledge, this study is the first to evaluate CABP1 polymorphisms in relation to the risk of adenoma. Our finding of a significant association is promising; however, the finding should be confirmed in future studies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3763. doi:10.1158/1538-7445.AM2011-3763

Abstract LB-452: Genetic polymorphisms in the TRPM7 gene and colorectal adenoma risk

Background: Several epidemiologic studies suggest that high magnesium intake is associated with reduced risk of colorectal cancer or colorectal adenoma. Results, however, have been inconsistent. Ionized magnesium (Mg2+) counters the action of ionized calcium (Ca2+) in many physiologic activities. We previously reported that the associations between intakes of magnesium, calcium or calcium/magnesium ratio with risk of colorectal polyp were modified by the common Thr1482Ile polymorphism in the gene for the transient receptor potential melastatin 7 (TRPM7), which is a ubiquitously expressed constitutive ion channel with a higher affinity for Mg2+ than for Ca2+ and plays a central role in magnesium homeostasis and magnesium (re)absorption pathways. Except for our earlier study, no other study has investigated these possible gene-nutrient interactions in the etiology of colorectal adenoma or cancer. In the present study, we examined single nucleotide polymorphisms (SNPs) in the TRPM7 gene and their interaction with calcium and magnesium intake or calcium/magnesium ratio in relation to risk of colorectal adenoma using data from the Tennessee Colorectal Polyp Study.

Methods: Included in the study were participants of the Tennessee Colorectal Polyp study, an ongoing colonoscopy-based case control study conducted in Nashville, TN. Genotyping was performed at Vanderbilt Microarray Shared Resource using the Affymetrix Genome-Wide Human SNP Array 5.0. Sixteen SNPs in the TRPM7 gene were genotyped for 958 colorectal adenoma cases and 909 controls. Hardy-Weinberg equilibrium was assessed for each SNP among controls. The associations of each genotype with colorectal adenoma risk were evaluated under dominant, recessive and additive models, respectively. Multivariate unconditional logistic regression models were used to estimate the odds ratio and 95% confidence intervals for each SNP. Multiplicative interactions were evaluated for gene-diet interactions using likelihood ratio tests.

Results: All the genotype frequencies for the TRPM7 were in Hardy-Weinberg equilibrium. Of the sixteen SNPs, Four SNPs were significantly associated with risk of colorectal adenoma whereas six SNPs significantly interacted with dietary calcium intake or the ratio of dietary calcium to magnesium intake (five SNPs with calcium and six with the ratio) in relation to risk of colorectal adenoma. The two sets of SNPs were not in strong linkage disequilibrium (LD). However, either three of the four associated SNPs or all of the six interacting SNPs were in strong LD with one another respectively. No significant interactions with magnesium intake were observed.

Conclusions: Our results suggest that genetic polymorphisms in the TRPM7 gene, particularly their interactions with calcium or calcium/magnesium ratio, contribute to risk of colorectal adenoma. Further replications in large-scale studies are ongoing.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-452. doi:10.1158/1538-7445.AM2011-LB-452

An automated database case definition for serious bleeding related to oral anticoagulant use

PURPOSE

Bleeding complications are a serious adverse effect of medications that prevent abnormal blood clotting. To facilitate epidemiologic investigations of bleeding complications, we developed and validated an automated database case definition for bleeding-related hospitalizations.

METHODS

The case definition utilized information from an in-progress retrospective cohort study of warfarin-related bleeding in Tennessee Medicaid enrollees 30 years of age or older. It identified inpatient stays during the study period of January 1990 to December 2005 with diagnoses and/or procedures that indicated a current episode of bleeding. The definition was validated by medical record review for a sample of 236 hospitalizations.

RESULTS

We reviewed 186 hospitalizations that had medical records with sufficient information for adjudication. Of these, 165 (89%, 95%CI: 83-92%) were clinically confirmed bleeding-related hospitalizations. An additional 19 hospitalizations (10%, 7-15%) were adjudicated as possibly bleeding-related. Of the 165 clinically confirmed bleeding-related hospitalizations, the automated database and clinical definitions had concordant anatomical sites (gastrointestinal, cerebral, genitourinary, other) for 163 (99%, 96-100%). For those hospitalizations with sufficient information to distinguish between upper/lower gastrointestinal bleeding, the concordance was 89% (76-96%) for upper gastrointestinal sites and 91% (77-97%) for lower gastrointestinal sites.

CONCLUSION

A case definition for bleeding-related hospitalizations suitable for automated databases had a positive predictive value of between 89% and 99% and could distinguish specific bleeding sites.

Outcomes with concurrent use of clopidogrel and proton-pump inhibitors: a cohort study

BACKGROUND

Proton-pump inhibitors (PPIs) and clopidogrel are frequently coprescribed, although the benefits and harms of their concurrent use are unclear.

OBJECTIVE

To examine the association between concurrent use of PPIs and clopidogrel and the risks for hospitalizations for gastroduodenal bleeding and serious cardiovascular disease.

DESIGN

Retrospective cohort study using automated data to identify patients who received clopidogrel between 1999 through 2005 after hospitalization for coronary heart disease.

SETTING

Tennessee Medicaid program.

PATIENTS

20,596 patients (including 7593 concurrent users of clopidogrel and PPIs) hospitalized for myocardial infarction, coronary artery revascularization, or unstable angina pectoris.

MEASUREMENTS

Baseline and follow-up drug use was assessed from automated records of dispensed prescriptions. Primary outcomes were hospitalizations for gastroduodenal bleeding and serious cardiovascular disease (fatal or nonfatal myocardial infarction or sudden cardiac death, stroke, or other cardiovascular death).

RESULTS

Pantoprazole and omeprazole accounted for 62% and 9% of concurrent PPI use, respectively. Adjusted incidence of hospitalization for gastroduodenal bleeding in concurrent PPI users was 50% lower than that in nonusers (hazard ratio, 0.50 [95% CI, 0.39 to 0.65]). For patients at highest risk for bleeding, PPI use was associated with an absolute reduction of 28.5 (CI, 11.7 to 36.9) hospitalizations for gastroduodenal bleeding per 1000 person-years. The hazard ratio associated with concurrent PPI use for risk for serious cardiovascular disease was 0.99 (CI, 0.82 to 1.19) for the entire cohort and 1.01 (CI, 0.76 to 1.34) for the subgroup of patients who had percutaneous coronary interventions with stenting during the qualifying hospitalization.

LIMITATIONS

Unmeasured confounding and misclassification of exposure (no information on adherence or over-the-counter use of drugs) and end points (not confirmed by medical record review) were possible. Because many patients entered the cohort from hospitals with relatively few cohort members, the analysis relied on the assumption that after adjustment for observed covariates, PPI users from one such hospital could be compared with nonusers from a different hospital.

CONCLUSION

In patients with serious coronary heart disease treated with clopidogrel, concurrent PPI use was associated with reduced incidence of hospitalizations for gastroduodenal bleeding. The corresponding point estimate for serious cardiovascular disease was not increased; however, the 95% CI included a clinically important increased risk.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality and National Heart, Lung, and Blood Institute.

Abstract 2859: Genetic polymorphisms in the PTH and PTHR1 genes and colorectal adenoma risk

Background: A number of cohort studies and randomized trials suggest that high calcium consumption may confer a reduced risk of colorectal cancer. Results, however, have been inconsistent. It is possible that the calcium effect may differ by polymorphisms in the genes involved in calcium regulation. Parathyroid hormone (PTH) is a critical hormone in the regulation of calcium concentration in extracellular fluid. The PTH and its receptors (PTHR) play an essential role in calcium homeostasis. Thus far, no study has been conducted to investigate the association of genetic variations in the PTH pathway and risk of colorectal adenoma or cancer. In the present study, we examined single nucleotide polymorphisms (SNPs) in the PTH and PTHR genes and their interaction with calcium intake in relation to risk of colorectal adenoma using data from the Tennessee Colorectal Polyp Study. Methods: Included in the study were participants of the Tennessee Colorectal Polyp study, an ongoing colonoscopy-based case control study conducted in Nashville, TN. Genotyping was performed at Vanderbilt Microarray Shared resource using the Affymetrix Human Mapping 500K array set. Three SNPs in the PTH gene and two SNPs in the PTHR1 were genotyped for 738 colorectal adenoma cases and 776 controls. Hardy-Weinberg equilibrium was assessed for each SNP among controls. The associations of each genotype with colorectal adenoma risk were evaluated under dominant, recessive and additive models, respectively. Multivariate unconditional logistic regression models were used to estimate the odds ratio and 95% confidence intervals for each SNP. Multiplicative interactions were evaluated for gene-diet interactions using likelihood ratio tests. Results: There were no significant differences in selected demographic characteristics and potential confounding factors between the colorectal adenoma case and control groups. All the genotype frequencies for PTH and PTHR1 were in Hardy-Weinberg equilibrium. There were no associations between the PTH genotypes and the risk for colorectal adenoma under dominant, recessive or additive models. One SNP (rs 7652849) in the PTHR1 gene was significantly associated with the risk of colorectal adenoma in both unadjusted model (OR: 1.32; 95%CI: 1.02, 1.71; p = 0.034) and adjusted model (OR: 1.32; 95%CI: 1.00, 1.73; p = 0.047). Furthermore, we found the SNP (rs 936173) in the PTHR1 gene significantly interacted with calcium intake in relation to risk of colorectal cancer (p = 0.046). No significant interactions with calcium intake were observed for the PTH gene. Conclusions: Our results suggest polymorphisms in PTHR1 may contribute to or interact with calcium intake in relation to risk of colorectal adenoma. Although further investigations of the PTHR1 gene polymorphisms on colorectal adenoma risk are required, our findings might provide some new insights into the mechanisms through which calcium reduces colorectal cancer risk.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2859.

Outcomes with concurrent use of clopidogrel and proton-pump inhibitors: a cohort study

BACKGROUND

Proton-pump inhibitors (PPIs) and clopidogrel are frequently coprescribed, although the benefits and harms of their concurrent use are unclear.

OBJECTIVE

To examine the association between concurrent use of PPIs and clopidogrel and the risks for hospitalizations for gastroduodenal bleeding and serious cardiovascular disease.

DESIGN

Retrospective cohort study using automated data to identify patients who received clopidogrel between 1999 through 2005 after hospitalization for coronary heart disease.

SETTING

Tennessee Medicaid program.

PATIENTS

20,596 patients (including 7593 concurrent users of clopidogrel and PPIs) hospitalized for myocardial infarction, coronary artery revascularization, or unstable angina pectoris.

MEASUREMENTS

Baseline and follow-up drug use was assessed from automated records of dispensed prescriptions. Primary outcomes were hospitalizations for gastroduodenal bleeding and serious cardiovascular disease (fatal or nonfatal myocardial infarction or sudden cardiac death, stroke, or other cardiovascular death).

RESULTS

Pantoprazole and omeprazole accounted for 62% and 9% of concurrent PPI use, respectively. Adjusted incidence of hospitalization for gastroduodenal bleeding in concurrent PPI users was 50% lower than that in nonusers (hazard ratio, 0.50 [95% CI, 0.39 to 0.65]). For patients at highest risk for bleeding, PPI use was associated with an absolute reduction of 28.5 (CI, 11.7 to 36.9) hospitalizations for gastroduodenal bleeding per 1000 person-years. The hazard ratio associated with concurrent PPI use for risk for serious cardiovascular disease was 0.99 (CI, 0.82 to 1.19) for the entire cohort and 1.01 (CI, 0.76 to 1.34) for the subgroup of patients who had percutaneous coronary interventions with stenting during the qualifying hospitalization.

LIMITATIONS

Unmeasured confounding and misclassification of exposure (no information on adherence or over-the-counter use of drugs) and end points (not confirmed by medical record review) were possible. Because many patients entered the cohort from hospitals with relatively few cohort members, the analysis relied on the assumption that after adjustment for observed covariates, PPI users from one such hospital could be compared with nonusers from a different hospital.

CONCLUSION

In patients with serious coronary heart disease treated with clopidogrel, concurrent PPI use was associated with reduced incidence of hospitalizations for gastroduodenal bleeding. The corresponding point estimate for serious cardiovascular disease was not increased; however, the 95% CI included a clinically important increased risk.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality and National Heart, Lung, and Blood Institute.

Fruit and vegetable intakes are associated with lower risk of colorectal adenomas

Many phytochemicals in fruits and vegetables have been shown to have cancer-inhibitory effects in animal studies. These effects on cancer, however, have not been clearly demonstrated in human studies. This study investigated the association between fruit and vegetable intakes and the risk of adenomatous polyps. Participants were part of the Tennessee Colorectal Polyp Study. Eligible participants aged 40-75 y were recruited from patients undergoing colonoscopy at 2 medical centers in Nashville, Tennessee from 2003 to 2005. Cases had at least one adenoma and controls were polyp free. Dietary intake was assessed using a self-administered FFQ. Associations between dietary intakes and adenoma risk were evaluated using unconditional logistic regression with restricted cubic function spline. In multivariate analyses of 764 cases and 1517 controls, increased intakes of total fruits, berries, fruit juice, and green leafy vegetables were associated with reduced adenoma risk. The odds ratio for upper tertile intake compared with lower was 0.66 (95% CI = 0.51-0.86) for total fruits, 0.64 (95% CI = 0.47-0.87) for berries, 0.72 (95% CI = 0.56-0.92) for fruit juice, and 0.74 (95% CI = 0.58-0.96) for green vegetables. This study provides additional evidence that high total fruit intake and certain fruit and vegetable intakes may be associated with a reduced risk of colorectal adenomas.

Meat intake, heterocyclic amine exposure, and metabolizing enzyme polymorphisms in relation to colorectal polyp risk

Most colorectal cancers arise from adenomatous polyps or certain hyperplastic polyps. Only a few studies have investigated potential genetic modifiers of the associations between meat intake and polyp risk, and results are inconsistent. Using data from the Tennessee Colorectal Polyp Study, a large colonoscopy-based study, including 1,002 polyp cases (557 adenoma only, 250 hyperplastic polyp only, 195 both polyps) and 1,493 polyp-free patients, we evaluated the association of colorectal polyp risk with carcinogen exposure from meat and genetic polymorphisms in enzymes involved in heterocyclic amine (HCA) metabolism, including N-acetyltransferase 1 (NAT1) and N-acetyltransferase 2 (NAT2), cytochrome P450 1A2 (CYP1A2), and aryl hydrocarbon receptor (AhR). Data on intake levels of meats by preparation methods, doneness preferences, and other lifestyle factors were obtained. Fourteen single nucleotide polymorphisms in the AhR, CYP1A2, NAT1, and NAT2 genes were evaluated. No clear association was found for any polymorphisms with polyp risk. However, apparent interactions were found for intake of meat and HCAs with AhR, NAT1, and NAT2 genotypes, and the interactions were statistically significant for the group with both adenomatous and hyperplastic polyps. Dose-response relationships with meat or HCA intake were found only among those with the AhR GA/AA (rs2066853) genotype, NAT1 rapid, or NAT2 rapid/intermediate acetylators but not among those with other genotypes of these genes. This dose-response relationship was more evident among those with both AhR GA/AA and the NAT1 rapid acetylator than those without this genotype combination. These results provide strong evidence for a modifying effect of metabolizing genes on the association of meat intake and HCA exposure with colorectal polyp risk.

Alcohol drinking, cigarette smoking, and risk of colorectal adenomatous and hyperplastic polyps

The authors evaluated alcohol drinking and cigarette smoking in relation to risk of colorectal polyps in a Nashville, Tennessee, colonoscopy-based case-control study. In 2003-2005, cases with adenomatous polyps only (n = 639), hyperplastic polyps only (n = 294), and both types of polyps (n = 235) were compared with 1,773 polyp-free controls. Unordered polytomous logistic regression was used to calculate adjusted odds ratios and 95% confidence intervals. Consumption of at least five alcoholic drinks per week was not strongly associated with development of polyps. Odds ratios for all polyp types were increased for dose, duration, and pack-years of cigarette smoking and were stronger for hyperplastic polyps than for adenoma. Compared with never smoking, dose-response relations were particularly strong for current smoking and duration; for > or =35 years of smoking, odds ratios were 1.9 (95% confidence interval (CI): 1.4, 2.5) for adenomatous polyps only, 5.0 (95% CI: 3.3, 7.3) for hyperplastic polyps only, and 6.9 (95% CI: 4.4, 11.1) for both types of polyps. Compared with current smoking, time since cessation was associated with substantially reduced odds; for > or =20 years since quitting, odds ratios were 0.4 (95% CI: 0.3, 0.6) for adenoma only, 0.2 (95% CI: 0.1, 0.3) for hyperplastic polyps only, and 0.2 (95% CI: 0.2, 0.4) for both polyp types. These findings support the adverse role of cigarette smoking in colorectal tumorigenesis and suggest that quitting smoking may substantially reduce the risk of colorectal polyps.

The relation of magnesium and calcium intakes and a genetic polymorphism in the magnesium transporter to colorectal neoplasia risk

BACKGROUND

Mean magnesium intake in the US population does not differ from that in East Asian populations with traditionally low risks of colorectal cancer and other chronic diseases, but the ratio of calcium to magnesium (Ca:Mg) intake is much higher in the US population. Transient receptor potential melastatin 7 (TRPM7) is a newly found gene essential to magnesium absorption and homeostasis.

OBJECTIVE

We aimed to test whether the association of colorectal polyps with intake of calcium, magnesium, or both and Thr1482Ile polymorphism in the TRPM7 gene is modified by the Ca:Mg intake.

DESIGN

Included in the study were a total of 688 adenoma cases, 210 hyperplastic polyp cases, and 1306 polyp-free controls from the Tennessee Colorectal Polyp Study.

RESULTS

We found that total magnesium consumption was linked to a significantly lower risk of colorectal adenoma, particularly in those subjects with a low Ca:Mg intake. An inverse association trend was found for hyperplastic polyps. We also found that the common Thr1482Ile polymorphism was associated with an elevated risk of both adenomatous and hyperplastic polyps. Moreover, this polymorphism significantly interacted with the Ca:Mg intake in relation to both adenomatous and hyperplastic polyps. The subjects who carried >or=1 1482Ile allele and who consumed diets with a high Ca:Mg intake were at a higher risk of adenoma (odds ratio: 1.60; 95% CI: 1.12, 2.29) and hyperplastic polyps (odds ratio: 1.85; 95% CI: 1.09, 3.14) than were the subjects who did not carry the polymorphism.

CONCLUSION

These findings, if confirmed, may provide a new avenue for the personalized prevention of magnesium deficiency and, thus, colorectal cancer.