Faculty Bibliography

Cooking meat at high temperatures produces heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Processed meats contain N-nitroso compounds. Meat intake may increase cancer risk as HCAs, PAHs, and N-nitroso compounds are carcinogenic in animal models. We investigated meat, processed meat, HCAs, and the PAH benzo(a)pyrene and the risk of colorectal adenoma in 3,696 left-sided (descending and sigmoid colon and rectum) adenoma cases and 34,817 endoscopy-negative controls. Dietary intake was assessed using a 137-item food frequency questionnaire, with additional questions on meats and meat cooking practices. The questionnaire was linked to a previously developed database to determine exposure to HCAs and PAHs. Intake of red meat, with known doneness/cooking methods, was associated with an increased risk of adenoma in the descending and sigmoid colon [odds ratio (OR), 1.26; 95% confidence interval (95% CI), 1.05-1.50 comparing extreme quintiles of intake] but not rectal adenoma. Well-done red meat was associated with increased risk of colorectal adenoma (OR, 1.21; 95% CI, 1.06-1.37). Increased risks for adenoma of the descending colon and sigmoid colon were observed for the two HCAs: 2-amino-3,8-dimethylimidazo[4,5]quinoxaline and 2-amino-1-methyl-6-phenylimidazo[4,5]pyridine (OR, 1.18; 95% CI, 1.01-1.38 and OR, 1.17, 95% CI, 1.01-1.35, respectively) as well as benzo(a)pyrene (OR, 1.18; 95% CI, 1.02-1.35). Greater intake of bacon and sausage was associated with increased colorectal adenoma risk (OR, 1.14; 95% CI, 1.00-1.30); however, total intake of processed meat was not (OR, 1.04; 95% CI, 0.90-1.19). Our study of screening-detected colorectal adenomas shows that red meat and meat cooked at high temperatures are associated with an increased risk of colorectal adenoma

BACKGROUND & AIMS: The efficacy of flexible sigmoidoscopy (FSG) in reducing colorectal cancer mortality is being evaluated in randomized trials. In 2 European trials, wide variability across examiners in FSG performance was noted. We report on the performance of examiners in the US randomized trial: the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. METHODS: Screening was performed at 10 geographically dispersed clinical centers. Patients with screens positive for a lesion or mass were referred to their private health care providers for endoscopic follow-up evaluation; lesions were not removed and a biopsy examination was not performed at screening. FSG performance among 64 examiners at these centers, each performing 100 or more baseline FSG examinations, with an aggregate of almost 50,000 examinations, was analyzed. RESULTS: Screen-positivity results among examiners ranged from 9%-58%, with a coefficient of variation (CV) of 36%. CVs were 29% for distal polyp detection and 21% for distal adenoma detection. Inadequate rates ranged from 1%-27% (CV, 52%). Examiners with higher screen-positivity rates had higher false-positive rates, defined as a positive screen with no distal lesion found on endoscopic follow-up evaluation. CONCLUSIONS: Considerable variability exists in the rates of positive screens and in polyp and adenoma detection rates among FSG examiners performing the procedures using a common protocol

BACKGROUND & AIMS: Insulin and insulin-like growth factor-I (IGF-I) affect proliferation, differentiation, and apoptosis and are potential risk factors for colorectal cancer (CRC). Visceral obesity, possibly via hyperinsulinemia, has also been linked to CRC risk. We evaluated the relationship of insulin, IGF-I, insulin-like growth factor binding protein (IGFBP) 3, and visceral adipose tissue (VAT) in subjects with adenomatous polyps, the precursor lesion of colorectal cancer. METHODS: Participants were asymptomatic subjects who underwent screening flexible sigmoidoscopy (FSG) within the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Subjects underwent single-slice, computerized tomography scanning to measure VAT and serum fasting insulin, IGF-I, and IGFBP-3 measurements. RESULTS: Four hundred fifty-eight subjects were enrolled, of which 202 subjects had an adenoma, 70 of which were an advanced adenoma. IGF-I (P = .02), IGF-I/IGFBP-3 ratio (P = .003), and insulin (P = .02) were significantly increased in subjects with adenomas compared with controls. In an unadjusted logistic regression analysis using sex-specific quartile cut points, subjects in quartile 4 in comparison with quartile 1 of IGF-I (odds ratio [OR] = 1.7; [95% CI: 1.0-2.9], Ptrend = .03), IGF-I/IGFBP-3 ratio (OR = 1.9 [95% CI: 1.1-3.3], Ptrend = .01), and insulin (OR = 2.1 [95% CI: 1.2-3.6], Ptrend = .04) were at increased risk of adenoma. When limiting the case group to advanced adenomas, the effect was more pronounced: IGF-I (OR = 2.8 [95% CI: 1.3-6.2], Ptrend = .006), IGF-I/IGFBP-3 ratio (OR = 2.3, [95% CI: 1.0-5.2], Ptrend = .04), and insulin (OR = 2.3 [95% CI: 1.1-4.9], Ptrend = .14). Visceral adipose tissue was not associated with adenoma risk. CONCLUSIONS: Levels of IGF-I, ratio of IGF-I/IGFBP-3, and insulin are associated with adenomas and even more so with advanced adenomas. These data support the hypothesis that insulin and IGF-I may contribute to the development and advancement of adenomatous polyps

Impaired DNA repair capacity may adversely affect cancer risk, particularly in subjects exposed to DNA damaging carcinogens, as found in tobacco smoke, or among subjects deficient for protective factors, as found in fruits and vegetables. We studied tobacco use, fruit and vegetable intake, and common non-synonymous single nucleotide polymorphisms in four DNA repair genes in relation to gastric cancer risk, in a population-based, case-control study of 281 incident gastric cancer cases and 390 controls, in Warsaw, Poland. Multivariate logistic regression analysis was performed to calculate odds ratios (OR) and 95% confidence intervals (CI). Increased risks of gastric cancer were found for smokers (OR=3.1, CI=1.9-5.1 for pack-years>or=40 versus never smokers) and subjects with low fruit intake (OR=2.2, CI=1.3-3.6 for 1st versus 4th quartile); risk associated with vegetable intake was not statistically significant. Allele frequencies among the controls were consistent with those previously reported for the 5 polymorphisms studied: XRCC1-Arg399Gln, XPD-Lys751Gln, MGMT-Ile143Val, Leu84Phe, and XRCC3-Thr241Met. None of the studied polymorphisms were independently associated with gastric cancer risk. Smoking-associated risks, however, were greatest for carriers of the XRCC1-399 ArgArg genotype (Pinteraction=0.004). Risks associated with low intake of fruits or vegetables tended to be modified by selected polymorphisms in XRCC1, XPD and MGMT (Pinteraction=0.1-0.2). Risk modification was not found for the other repair polymorphisms. Selected DNA repair polymorphisms did not have independent effects on gastric cancer risk; however, they may modify smoking- and probably diet-related risks for this disease. These results need replication in larger epidemiological studies of gastric cancer

Cigarette smoking is a risk factor for colon adenoma. The glutathione S-transferase enzymes are involved in the detoxification of carcinogenic compounds including those found in tobacco smoke, and thus, may be important modifiers of individual risk of developing this disease. We examined the prevalence of GSTM1 and GSTT1 gene deletions, and two GSTP1 polymorphisms in 772 cases with advanced colorectal adenomas (>1 cm, villous elements or high-grade dysplasia) of the distal colon (descending or sigmoid colon or rectum) and 777 sigmoidoscopy negative controls enrolled in the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Epidemiologic data on smoking was collected by self-administered questionnaire and DNA was extracted from whole blood or buffy coat. For GSTM1 and GSTT1, we used a newly developed TaqMan-based assay capable of discriminating heterozygous (+/-) individuals from those with two active alleles (+/+) and homozygous deletions (-/-). For GSTP1, the I105V and the A114V substitutions were identified using end point 5' nuclease assays (TaqMan). Adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were determined using unconditional logistic regression, controlling for age, race, and gender. Advanced adenoma risk was increased in current/former smokers (OR, 1.4; 95% CI, 1.2-1.8). Risks were decreased in subjects with > or =1 inactive GSTM1 alleles (OR, 0.6; 95% CI, 0.4-0.9); and the association was independent of smoking status (P interaction = 0.59). Having > or =1 inactive GSTT1 allele was associated with increased risk among smokers (OR, 1.4; 95% CI, 1.1-1.9; P trend = 0.02) but not among never smokers (OR, 0.9; 95% CI, 0.6-1.3) and a significant interaction between smoking and genotype was observed (P interaction = 0.05). In summary, this is the first study to report associations between colorectal adenomas and GSTM1 wild-type and GSTT1 null allele among smokers. These findings only became apparent using a newly developed assay able to distinguish heterozygous from wild-type individuals. Our data provide evidence that phenotypic differences between these two groups exist

Tobacco and alcohol consumption are the major risk factors for head and neck cancer, likely due to DNA-damaging processes. Genetic variations in DNA repair genes may affect an individual's susceptibility to head and neck cancer. Pooling data and DNA specimens from three case-control studies in western Washington State, North Carolina, and Puerto Rico, totaling 555 cases (430 whites) and 792 controls (695 whites), we studied the risk of head and neck cancer in relation to common nonsynonymous single-nucleotide polymorphisms in four DNA repair genes: MGMT (Leu84Phe and Ile143Val), XRCC1 (Arg399Gln), XPD (Lys751Gln), and XRCC3 (Thr241Met). All single-nucleotide polymorphisms were assayed in a single laboratory. Among whites, carriage of the MGMT Phe84 [odds ratio (OR), 0.71; 95% confidence interval (95% CI), 0.51-0.98] or Val143 (OR, 0.66; 95% CI, 0.47-0.92) allele was associated with a decreased risk of head and neck cancer; the haplotype distribution for MGMT differed significantly between cases and controls (covariate-adjusted global permutation test, P = 0.012). The XRCC1 GlnGln399 genotype was also associated with decreased risk among whites (OR, 0.56; 95% CI, 0.32-0.94), whereas XPD751 and XRCC3241 were not associated with risk. Alcohol-related risks tended to vary with DNA repair genotypes, especially for MGMT variants, whereas no effect modification was noted with tobacco use. Consistent findings from three case-control studies suggest that selected DNA repair enzymes may play a role in head and neck carcinogenesis

The purpose of this study was to gain insights into the variations seen in the electron paramagnetic resonance (EPR) spectroscopy of the native signals of teeth and bones used for retrospective dosimetry measurements. We determined that changes occur in the long-lived free radicals responsible for the native signal of cortical bone in aging or diseased human females and aged ovariectomized rats. This was done by measuring the magnitude of the broad (BC) and narrow (NC) components of the native EPR signal of bone following chemical extraction, aging, crushing and thermal annealing. Bone from the upper midshaft of femora of young (17-34 years old, n=5) and elderly (70-92 years old, n=18) females was examined. The results showed that the elderly women had significantly higher BC than the younger women (P<0.01). A similar interpretation was made of the data from an aging female rat osteoporosis model. The results for the NC signals were similar. Finally, dramatic decreases in both NC and BC signals were seen in HIV positive and uncontrolled diabetic (one each) patients indicating the need for studying this signal for a broad spectrum of metabolic disorders. Experiments were performed which strongly indicate that iron liganded with organic molecules is the source of the BC signal. Finally, the accuracy achieved in this study indicates that resolving the dosimetric signal (g=2.0018) should be improved by subtraction of the deconvoluted NC and BC signals from the original spectrum

Cigarette use is a risk factor for colorectal adenoma, a known precursor of colorectal cancer. Polymorphic variants in NQO1 and CYP1A1 influence the activation of carcinogenic substances in tobacco smoke, possibly impacting on tobacco-associated risks for colorectal tumors. We investigated the association of cigarette smoking with risk for advanced colorectal adenoma in relation to the CYP1A1 Val(462) and NQO1 Ser(187) polymorphic variants. Subjects were 725 non-Hispanic Caucasian cases with advanced colorectal adenoma of the distal colon (descending colon, sigmoid and rectum) and 729 gender- and ethnicity-matched controls, randomly selected from participants in the prostate, lung, colorectal and ovarian cancer screening trial. Subjects carrying either CYP1A1 Val(462) or NQO1 Ser(187) alleles were weakly associated with risk of colorectal adenoma; however, subjects carrying both CYP1A1 Val(462) and NQO1 Ser(187) alleles showed increased risks (OR = 2.2, 95% CI = 1.1-4.5), particularly among recent (including current) (OR = 17.4, 95% CI = 3.8-79.8, P for interaction = 0.02) and heavy cigarette smokers (>20 cigarettes/day) (OR = 21.1, 95% CI = 3.9-114.4, P for interaction = 0.03) compared with non-smokers who did not carry either of these variants. These genotypes were unassociated with risk in non-smokers. In analysis of adenoma subtypes, the combined gene variants were most strongly associated with the presence of multiple adenoma (P = 0.002). In summary, joint carriage of CYP1A1 Val(462) and NQO1 Ser(187) alleles, particularly in smokers, was related to colorectal adenoma risk, with a propensity for formation of multiple lesions

OBJECTIVES AND METHODS: Risks of oral cancer related to a CA microsatellite repeat polymorphism in intron 1 of the epidermal growth factor receptor (EGFR) gene and a TaqI polymorphism in the transforming growth factor-alpha (TGFA) gene were evaluated in a population-based case-control study consisting of 157 cases and 149 controls recruited in Puerto Rico. RESULTS: Carriers of > or = 16 CA repeats in EGFR showed a 1.9-fold increased risk for oral cancer (OR=1.9, 95% CI=1.0-3.5). Risks also tended to increase with decreasing number of alleles with > or = 16 CA repeats (P for trend=0.06). Our data suggested a non-significant reduction in risk for subjects heterozygous for the TGFA polymorphism (OR=0.6, 95% CI=0.2-1.3). CONCLUSIONS: The EGFR-associated risk appeared to be independent of tobacco and alcohol use and may be restricted primarily to subjects who consumed low amounts of fresh fruits and vegetables (OR=5.9, 95%CI: 2.3-15.2). These data implicate dietary and molecular targets for oral cancer prevention

PURPOSE: The benefit of prostate specific antigen (PSA) and digital rectal examination (DRE) screening for prostate cancer is under evaluation in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. Followup of positive screens in PLCO is done by subject personal physicians and it is outside of trial control. We describe the pattern of prostate biopsy in men with positive screens in PLCO. MATERIALS AND METHODS: We examined all men with positive baseline PSA or DRE screens and men with positive post-baseline screens occurring by December 2000. RESULTS: Of 2,717 men with positive PSA (greater than 4 ng/ml) at baseline 41% and 64% underwent biopsy within 1 and 3 years, respectively. A screening PSA of 7 to 10 and greater than 10 ng/ml at baseline was associated with significantly higher biopsy rates (HR 1.9 and 2.6, respectively) compared to PSA 4 to 7 ng/ml. The 1,793 in men whom the first positive PSA was after baseline had a lower overall biopsy rate (50% within 3 years). Furthermore, PSA above 7 ng/ml were not associated with higher biopsy rates in this group. The 4,449 men with positive DRE screens and negative PSA had a 3-year biopsy rate of 27%. Men with positive DRE at diagnostic followup had a biopsy rate of around 90%. However, few men, even of those with positive DRE screens, had positive diagnostic DREs. CONCLUSIONS:: These biopsy rates following positive PSA and DRE screens are likely to be representative of national rates. These results suggest that PLCO is evaluating the effects of screening in a contemporary and robust manner