Polymorphisms in inflammatory genes, plasma antioxidants, and prostate cancer risk.

BACKGROUND: Presence of xenotropic murine leukemia virus-related virus and chronic inflammation in prostate tumor suggests that inflammation plays a role in prostate cancer etiology. This study investigated whether variants in inflammatory genes act alone or interact with plasma antioxidants to influence prostate cancer risk in a population-based case-control study in Central Arkansas. METHODS: Cases (n = 193) were men, aged 40-80, diagnosed with prostate cancer in three major hospitals in 1998-2003, and controls (n = 197) were matched to cases by age, race, and county of residence. RESULTS: After adjustment for confounders, polymorphisms in COX-2 (rs689466) and IL-8 (rs4073) were not significantly associated with prostate cancer risk. However, apparent interactions were observed between these genetic variants and plasma antioxidants on the risk of this malignancy. The protective effect of the mutant allele of the COX-2 polymorphism was more pronounced among subjects with high plasma levels of beta-cryptoxanthin, lycopene, beta-carotene, or selenium (>or=median) [e.g., OR (95% CI): 0.37 (0.15, 0.86) (AG/GG vs. AA) for beta-cryptoxanthin]. Conversely, the promoting effect of the variant allele of the IL-8 polymorphism was more remarkable in subjects with low plasma levels of Lutein/zeaxanthin, beta-cryptoxanthin, and beta-carotene (

Physical activity, diet, and pancreatic cancer: a population-based, case-control study in Minnesota.

Although mounting evidence suggests that insulin resistance is involved in pancreatic carcinogenesis, few epidemiologic studies have comprehensively investigated the role of lifestyle factors influencing this metabolic disorder in the etiology of pancreatic cancer. We sought to examine this problem in a case-control study conducted in 1994-1998 in Minnesota. Cases (n = 186), aged 20 yr or older, were ascertained from all hospitals in the metropolitan area of the Twin Cities and the Mayo Clinic; from the latter, only cases residing in the Upper Midwest of the United States were recruited. Controls (n = 554) were randomly selected from the general population and frequency matched to cases by age (within 5 yr) and sex. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression. After adjustment for confounders, physical activity was associated with a reduced risk, but this protective effect was confined to light activity and moderate activity only (OR = 0.55, 95% CI = 0.30-0.97, P(trend) = 0.038 and OR = 0.51, 95% CI = 0.28-0.93, P(trend) = 0.07, for highest vs. lowest quartile, respectively). An increased risk was found for dietary intakes of energy and fat but was statistically significant for saturated and polyunsaturated fat only. Of note, no appreciable difference in the magnitude of the associations existed between saturated, monounsaturated, and polyunsaturated fat. Compared with individuals in the lowest quartile of fiber intake, the risk was approximately halved for those in the third (OR = 0.49, 95% CI = 0.26-0.94) and the highest quartile (OR = 0.52, 95% CI = 0.21-1.30). Our study lends support to the hypothesis that dietary and other lifestyle factors influencing insulin resistance modulate pancreatic cancer risk.

Phenotypic CYP2A6 variation and the risk of pancreatic cancer.

OBJECTIVE: Cytochrome P450 2A6 (CYP2A6) is an important metabolic enzyme capable of activating several procarcinogens, including dietary and tobacco-specific nitrosamines, which have been linked to pancreatic cancer. Positive associations between high CYP2A6 activity and lung and colorectal cancers have been reported. This is the first investigation of CYP2A6 activity and pancreatic cancer. DESIGN: In this case-control study of cancer of the exocrine pancreas, phenotypic CYP2A6 activity was measured using a ratio of urinary caffeine metabolites. Demographic, smoking, dietary and medical information were obtained by questionnaire. CYP2A6 phenotype, which is not influenced by smoking status, was measured for 90 cases and 470 controls. RESULTS: When modeled as a continuous variable, and adjusted for age, sex, race, education, current smoking status and chronic pancreatitis, the odds ratio (OR) per one unit of the natural log of the CYP2A6 ratio was 1.52 (95% confidence interval, CI: 1.09-2.12). In an adjusted categorical analysis, subjects in the uppermost quartile (based on controls) of CYP2A6 activity, when compared to the lower three quartiles, carried an 80% greater risk of pancreatic cancer (OR=1.80; 95% CI: 1.07-3.02). CONCLUSIONS: High levels of CYP2A6 activity, as measured by a caffeine phenotyping assay, were positively associated with pancreatic cancer in this casecontrol study among a Midwestern U.S. population.

The urinary metabolite profile of the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine is predictive of colon DNA adducts after a low-dose exposure in humans.

Epidemiologic evidence indicates that exposure to heterocyclic amines in the diet is an important risk factor for the development of colon cancer. Well-done cooked meats contain significant levels of heterocyclic amines, which have been shown to cause cancer in laboratory animals. To better understand the mechanisms of heterocyclic amine bioactivation in humans, the most mass abundant heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), was used to assess the relationship between PhIP metabolism and DNA adduct formation. Ten human volunteers where administered a dietary relevant dose of [(14)C]PhIP 48 to 72 hours before surgery to remove colon tumors. Urine was collected for 24 hours after dosing for metabolite analysis, and DNA was extracted from colon tissue and analyzed by accelerator mass spectrometry for DNA adducts. All 10 subjects were phenotyped for cytochrome P4501A2 (CYP1A2), N-acetyltransferase 2, and sulfotransferase 1A1 enzyme activity. Twelve PhIP metabolites were detected in the urine samples. The most abundant metabolite in all volunteers was N-hydroxy-PhIP-N(2)-glucuronide. Metabolite levels varied significantly between the volunteers. Interindividual differences in colon DNA adducts levels were observed between each individual. The data showed that individuals with a rapid CYP1A2 phenotype and high levels of urinary N-hydroxy-PhIP-N(2)-glucuronide had the lowest level of colon PhIP-DNA adducts. This suggests that glucuronidation plays a significant role in detoxifying N-hydroxy-PhIP. The levels of urinary N-hydroxy-PhIP-N(2)-glucuronide were negatively correlated to colon DNA adduct levels. Although it is difficult to make definite conclusions from a small data set, the results from this pilot study have encouraged further investigations using a much larger study group.

Associations between catalase phenotype and genotype: modification by epidemiologic factors.

Catalase is an endogenous antioxidant enzyme that neutralizes hydrogen peroxide and is induced by oxidative challenge. A -262C --> T polymorphism in the promoter region of the gene (CAT) is associated with risk of several conditions related to oxidative stress. We sought to determine the functional effects of the CAT polymorphism on enzyme activity in erythrocytes and the potential modifying effects of demographic and lifestyle factors on genotype/phenotype relationships, using specimens and data from controls from breast and prostate cancer studies in Arkansas (n = 420). There was a dose-response reduction in catalase activity by genotype, with geometric means of 115.4 units/mg hemoglobin for those with CC genotypes, 82.1 units/mg for those with CT genotypes, and 73.5 units/mg for those with TT genotypes. Associations were only observed among Caucasians (P < 0.0001), with no effects among African Americans (P = 0.91), and were stronger among women than men, although numbers in stratified analyses were small. Differences in catalase activity by genotype were most pronounced among those in the highest tertiles of consumption of fruits and vegetables (-35%, P = 0.003), with weaker relationships among those who were lower consumers (-21.8%, P = 0.16). Among those with CC genotypes, there was no change in activity by consumption, but there were notable decreases in activity by tertiles of consumption for those with at least one T allele. These data indicate that the CAT -262C --> T polymorphism predicts a portion of catalase phenotype, which may be limited to Caucasians. Associations between genotype and phenotype were modified by dietary factors, illustrating the biochemical complexity of studies of genetic polymorphisms and disease risk.

Association of SULT2A1 allelic variants with plasma adrenal androgens and prostate cancer in African American men.

Dehydroepiandrosterone (DHEA) sulfate which is present at micromolar levels in the plasma, can be desulfated to supply free DHEA for metabolism to androgens or estrogens in peripheral tissues. Human cytosolic sulfotransferase (SULT) 2A1 catalyzes DHEA sulfation in the adrenal cortex. Three SULT2A1 nonsynonymous coding single nucleotide polymorphisms (SNPs), identified only in African Americans (AA), are associated with decreased levels of activity and expression as compared to wild-type cDNA when expressed in COS cells. To test whether the SNPs are associated with decreased plasma androgens, 124 normal AA men were genotyped and plasma DHEA, DHEA-sulfate and testosterone levels determined. The two SNPs identified in these participants occurred at allelic frequencies of 0.044 (G187C) and 0.101 (G781A). The G187C SNP was highly linked to the G781A SNP. Although no differences in hormone levels were associated with the individual SNPs, a significant increase in the DHEA:DHEA-sulfate ratio was observed in participants with a heterozygous G187C/G781A genotype. Increased free DHEA levels may result in increased testosterone synthesis and stimulation in the prostate, therefore a group of AA prostate cancer (PC) patients and controls were genotyped. No significant association of the presence of the different SULT2A1 alleles with the occurrence of PC was detected.

Discordance between N-acetyltransferase 2 phenotype and genotype in a population of Hmong subjects.

Polymorphisms of N-acetyltransferase 2 (NAT2) acetylation may influence drug toxicities and efficacy and are associated with a differential susceptibility to select cancers. Acetylation phenotype may have clinical implications. The purposes of this study were to determine the genetic basis of an apparent predominance of slow acetylation phenotype and to assess concordance with genotype in a population of Hmong residing in Minnesota. Urine and DNA obtained from unrelated Hmong 18 to 65 years of age were used to determine phenotype from caffeine metabolites, whereas direct nucleotide sequencing of the NAT2 coding region, followed by cloning, identified all known allelic variants. From 61 subjects (27 men, 30 +/- 11 years), analysis of 50 urine-DNA pairs identified 46 (92%) slow acetylators and 4 (8%) rapid acetylators by phenotype. Genotypic analysis inferred 5 (10%) slow acetylators and 45 (90%) rapid acetylators. There is 86% discordance between phenotype and genotype. A predominance of NAT2 slow acetylation phenotype in the Hmong is confirmed, and a significant discordance between NAT2 phenotype and genotype is identified. In this population, slow acetylation phenotype determined by a metabolic probe would not have been predicted by genotype alone. Environmental, genetic, or phenotypic anomalies that may contribute to this discordance should be considered and evaluated in future studies within this unique population.

Association between sulfotransferase 1A1 genotype and survival of breast cancer patients receiving tamoxifen therapy.

BACKGROUND: Human sulfotransferase 1A1 (SULT1A1) catalyzes the sulfation of a variety of phenolic and estrogenic compounds, including 4-hydroxytamoxifen (4-OH TAM), the active metabolite of tamoxifen. A functional polymorphism in exon 7 of the SULT1A1 gene (SULT1A1*2) has been described that generates an enzyme that has approximately twofold lower activity and is less thermostable than that of the common allele SULT1A1*1. We investigated the hypothesis that that high sulfation activity would increase the elimination of 4-OH TAM by examining whether the presence of this polymorphism affects the efficacy of tamoxifen therapy. METHODS: We examined the relationship between the SULT1A1*2 allele and survival in a cohort of 337 women with breast cancer who received tamoxifen (n = 160) or who did not (n = 177). SULT1A1 genotype was determined by restriction fragment polymorphism analysis. Patient survival was evaluated according to SULT1A1 genotype using Kaplan-Meier survival functions. Hazard ratios (HRs) were calculated from adjusted Cox proportional hazards modeling. All statistical tests were two-sided. RESULTS: Among tamoxifen-treated patients, those who were homozygous for the SULT1A1*2 low-activity allele had approximately three times the risk of death (HR = 2.9, 95% confidence interval [CI] = 1.1 to 7.6) as those who were homozygous for the common allele or those who were heterozygous (SULT1A1*1/*2). Among patients who did not receive tamoxifen, there was no association between survival and SULT1A1 genotype (HR = 0.7, 95% CI = 0.3 to 1.5). CONCLUSIONS: Sulfation of 4-OH TAM provides a previously unanticipated benefit, possibly due to alterations in the bioavailability of the active metabolite or to undefined estrogen receptor-mediated events. These data alternatively suggest that variability in the metabolism of tamoxifen may affect its efficacy.

Dietary intake of heterocyclic amines and benzo(a)pyrene: associations with pancreatic cancer.

OBJECTIVE: Heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons, formed in temperature- and time-dependent manners during the cooking of meat, are mutagens and carcinogens. We sought to assess the association between dietary intake of HCA and benzo(a)pyrene [B(a)P] and exocrine pancreatic cancer in a population-based case-control study. METHODS: Subjects (193 cases and 674 controls) provided information on their usual meat intake and preparation method, e.g., stewed, fried, or grilled/barbecued, etc. Meat doneness preferences were measured using photographs that showed internal doneness and external brownness. We used a meat-derived HCA, B(a)P, and mutagen database with a questionnaire to estimate intake of PhIP, DiMeIQx, MeIQx, B(a)P, and mutagenic activity (revertants/g of daily meat intake). Data were analyzed with unconditional logistic regression. RESULTS: In analyses adjusted for age, sex, smoking, education, race, and diabetes, the odds ratio and 95% confidence interval for the highest compared with the lowest quintile were as follows: PhIP, 1.8 (1.0-3.1); DiMeIQx, 2.0 (1.2-3.5); MeIQx, 1.5 (0.9-2.7); B(a)P, 2.2 (1.2-4.0); and mutagenic activity, 2.4 (1.3-4.3). CONCLUSIONS: HCAs and B(a)P from well-done barbecued and pan-fried meats may be associated with increased risk for pancreatic cancer.

CYP3A43 Pro(340)Ala polymorphism and prostate cancer risk in African Americans and Caucasians.

The human cytochrome P450 3A subfamily of enzymes is involved in the metabolism of steroid hormones, carcinogens, and many drugs. A cytosine-to-guanine polymorphism in CYP3A43 results in a proline-to-alanine substitution at codon 340. Although the functional significance of this polymorphism is unknown, we postulate that the substitution of proline, an alpha-imino acid, with alanine, an amino acid, could be of biochemical significance. In a case-control study with 490 incident prostate cancer cases (124 African Americans and 358 Caucasians) and 494 controls (167 African Americans and 319 Caucasians), we examined the association between CYP3A43 Pro(340)Ala polymorphism and prostate cancer risk. When all subjects were considered, there was a 3-fold increase in risk of prostate cancer among individuals with the CYP3A43-Ala/Ala genotype (odds ratio, 3.0; 95% confidence interval, 1.2-7.2) compared with those with the CYP3A43-Pro/Pro genotype after adjusting for age, race, and smoking. The prevalence of the polymorphism was significantly higher in African Americans than Caucasians (45% versus 13%). In African Americans, there was a 2.6-fold increase in prostate cancer risk among individuals with the CYP3A43-Ala/Ala genotype (odds ratio, 2.6; 95% confidence interval, 1.0-7.0) compared with those with the CYP3A43-Pro/Pro genotype. Among Caucasians, the small number of homozygotes precluded computing risk estimates; there were only three individuals with the CYP3A43-Ala/Ala genotype. Our results suggest that the CYP3A43-Pro(340)Ala polymorphism contributes to prostate cancer risk.

Genetic polymorphisms in heterocyclic amine metabolism and risk of colorectal adenomas.

High red meat intake has been linked with an increased risk of colorectal cancer and adenomas. During high temperature cooking of red meats, heterocyclic amines (HCAs) are generated; however, to be carcinogenic, they must be metabolized by enzymes including cytochrome P450 1A2 (CYP1A2) and N-acetyltransferase 1 (NAT1) and/or N-acetyltransferase 2 (NAT2). We have conducted a clinic-based case-control study of colorectal adenomas that focused on assessment of exposure to HCAs (estimated by use of a HCA database and meat cooking module) and modification of these exposures by genetic factors. We have previously reported that intake of MeIQx was associated with an increased risk of colorectal adenomas [overall association at 80th percentile, > 27.00 ng/day: odds ratio (OR) = 2.68, 95% confidence interval (CI) 1.58-4.55]. Here, we report our evaluation of whether variation in CYP1A2, NAT1 and/or NAT2 modify the association between HCAs and colorectal adenoma formation in 146 cases and 228 frequency-matched controls. The NAT1*10 allele was associated with a nonsignificant increased risk of colorectal adenomas (OR = 1.43; 95% CI 0.86-2.36). Further, when we analysed 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) intake as a categorical variable, we observed a six-fold increase in adenoma risk among rapid NAT1 acetylators who consumed more than 27 ng a day (OR = 6.50; 95% CI 2.16-19.7), whereas among slow NAT1 acetylators, the increase in risk was two-fold (OR = 2.32; 95% CI 1.12-4.81). While suggestive, the results were not significantly different from each other on either an additive or multiplicative scale. In contrast, NAT2 genotype and CYP1A2 and NAT2 hepatic activity measured by caffeine urinary metabolites were not associated with adenoma risk, although an increase in risk with rapid CYP1A2 activity could not be ruled out (OR = 1.46; 95% CI 0.76-2.81). Moreover, there was no evidence that the effect of MeIQx was enhanced among subjects in any subgroup defined by variation in these measures. These results are compatible with the hypothesis that high HCA exposure is associated with an increased risk of colorectal adenomas, particularly in genetically susceptible subgroups. Further study of larger populations is needed to confirm and extend these observations.

CYP2A6 activity determined by caffeine phenotyping: association with colorectal cancer risk.

Cytochrome P450 2A6 (CYP2A6) catalyzes the metabolic activation of several procarcinogens including dietary and environmental nitrosamines, and the involvement of CYP2A6 in cancer development has been postulated. CYP2A6 phenotype was determined using caffeine as a probe drug in individuals participating in a case-control study of colorectal cancer (127 cases and 333 controls matched on age, gender, race, and geographic region). Conversion of the caffeine metabolite 1,7-dimethylxanthine (17X) to 1,7-dimethyl uric acid (17U) is catalyzed primarily by CYP2A6, and this activity can be assayed by comparison of urinary molar ratios of metabolites. Caffeine (200 mg) was administered to each participant, and a 4-5 h postadministration urine sample was collected. Urinary metabolites of caffeine were separated by high-performance liquid chromatography and quantified by comparison to authentic standards. We examined the distributions of the ratio, 17U:17X, according to subject characteristics among controls. In case-control comparisons, subjects in the medium and high tertiles of CYP2A6 activity had an increased risk of colorectal cancer compared with subjects with low activity. Odds ratios from a conditional logistic regression model for medium and high 17U:17X ratio were 2.0 (95% confidence interval, 1.1-3.7) and 2.6 (95% confidence interval, 1.5-4.5), respectively (P for trend = 0.001). CYP2A6 phenotype has not been compared previously between cancer cases and controls. We found a strong relationship between CYP2A6 activity, measured by urinary caffeine metabolite ratio, and colorectal cancer risk.

Association of SULT1A1 phenotype and genotype with prostate cancer risk in African-Americans and Caucasians.

Exposure to heterocyclic amines may increase prostate cancer risk. Human sulfotransferase 1A1 (SULT1A1) is involved in the bioactivation of some dietary procarcinogens, including the N-hydroxy metabolite of the food-borne heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo(4,5-b) pyridine. This study compares a polymorphism in the SULT1A1 gene, SULT1A1 enzyme activity, meat consumption, and the risk of prostate cancer in a population based case-control study. Prostate cancer patients (n = 464) and control individuals (n = 459), frequency matched on age and ethnicity, provided informed consent, answered a survey, and provided a blood sample. Platelets were isolated for phenotype analysis, and DNA was isolated from lymphocytes for genotype determination. Meat consumption was assessed using a dietary questionnaire. Caucasians homozygous for the SULT1A1*1 high activity allele were at increased risk for prostate cancer [odds ratio (OR), 1.68; 95% confidence interval (CI), 1.05-2.68] compared with individuals homozygous for the low-activity allele. The association between SULT1A1 genotype and prostate cancer risk in African-Americans did not reach significance (OR, 1.60; 95% CI, 0.46-5.62). When SULT1A1 activity was considered, there was a strong association between increased SULT1A1 activity and prostate cancer risk in Caucasians (OR, 3.04; 95% CI, 1.8-5.1 and OR, 4.96; 95% CI, 3.0-8.3, for the second and third tertiles of SULT1A1 activity, respectively) compared with individuals in the low enzyme activity tertile. A similar association was also found in African-American patients, with ORs of 6.7 and 9.6 for the second and third tertiles of SULT1A1 activity (95% CI, 2.1-21.3 and 2.9-31.3, respectively). When consumption of well-done meat was considered, there was increased risk of prostate cancer (OR, 1.42; 95% CI, 1.01-1.99 and OR, 1.68; 95% CI, 1.20-2.36 for the second and third tertiles, respectively). When SULT1A1 activity was stratified by tertiles of meat consumption, there was greater risk of prostate cancer in the highest tertile of meat consumption. These results indicate that variations in SULT1A1 activity contributes to prostate cancer risk and the magnitude of the association may differ by ethnicity and be modified by meat consumption.

Lack of association between Caucasian lung cancer risk and O6-methylguanine-DNA methyltransferase-codon 178 genetic polymorphism.

The formation of DNA adducts is thought to be a critical step for the induction of chemically induced cancer. O(6)-Methylguanine-DNA methyltransferase (MGMT) is a ubiquitously expressed enzyme that repairs DNA adducts formed by alkylating carcinogens. Thus, genetic polymorphisms of the MGMT that could result in differences in MGMT activity are potential risk factors for cancer. In the present study, we established a convenient and reliable genotyping method for the MGMT codon 178 polymorphism, a Lys (AAG) to Arg (AGG) substitution, using restriction fragment length polymorphism (RFLP), and studied differences in the distribution of this polymorphism in 92 Caucasian lung cancer patients and 85 controls. Frequencies of the "A" and "G" alleles (MGMT codon 178, AAG and AGG, respectively) were 0.91 and 0.09, respectively. The genetic polymorphism of the MGMT codon 178 was linked with that of the MGMT codon 143 (P < 0.05). The distribution of the MGMT codon 178 genetic polymorphism was not significantly different between lung cancer patients and controls. Thus, our study suggests that the MGMT codon 178 (and possibly 143) polymorphisms do not appear to markedly affect lung cancer risk for this population. In addition, we found an apparent 10bp-deletion in the intron before exon 5 by DNA sequencing. Because this "deletion" was observed in all sequenced samples (N = 20), the previously reported human (Caucasian) MGMT gene sequence should be revised to exclude this 10bp segment.

Effects of the ADH3, CYP2E1, and GSTP1 genetic polymorphisms on their expressions in Caucasian lung tissue.

Individual differences in lung cancer susceptibility should be considered for effective lung cancer prevention. We investigated the CYP2E1, ADH3, and GSTP1 genetic polymorphisms that biotransform xenobiotic carcinogens, and variations of their enzyme activity in Caucasian lung tissues (N=28), and found a variant distribution in pulmonary ADH and CYP2E1 activity. The ADH3*1/*1 subjects (N=8) showed significantly higher ADH activity than ADH3*2/*2 (N=3) subjects (P<0.01). On the other hand, we found a 5-fold variation in the pulmonary CYP2E1 activity using a sensitive HLPC/EC based technique. A subject with the CYP2E1-c/t allele showed 2-fold higher CYP2E1 activity than subjects with the c/c allele (N=14). GSTP1 expression comprised 83% of the total pulmonary GSTs. However, neither the GSTP1 polymorphism, nor other lifestyle factors, such as age, gender, smoking status, were found to be associated with pulmonary GST expression. In conclusion, subjects with the ADH3*1 allele showed higher ADH activity and acetaldehyde-DNA adducts in lung than other subjects; thus, the ADH3*1 allele could be considered a risk factor for lung cancer.

Novel markers of susceptibility to carcinogens in diet: associations with colorectal cancer.

Red meats cooked at high temperatures generate mutagenic heterocyclic amines, which undergo metabolic activation by hepatic cytochrome P450 1A2 and N-acetyltransferase-2. A primary detoxification pathway involves glutathione S-transferase A1 (GSTA1), which catalyzes the reduction of the carcinogenic N-acetoxy derivative back to the parent amine. Recently, we described a polymorphism in the GSTA1 proximal promoter; the variant (GSTA1*B) allele significantly lowers enzyme expression. In a case-control study, GSTA1*B/*B genotype was associated with an increased risk of colorectal cancer, particularly among consumers of well-done meat. Dietary nitrosamines, which are bioactivated by CYP2A6, represent another potential etiologic factor for colorectal cancer. CYP2A6 converts the caffeine metabolite 1,7-dimethylxanthine (17X) to 1,7-dimethyluric acid (17U); we investigated CYP2A6 activity using the 17U/17X urinary metabolite ratio from case-control subjects who completed a caffeine phenotype assay. The distribution of CYP2A6 activity was significantly different between CRCa cases and controls, with subjects in the medium and high activity groups having an increased risk (P for trend=0.001). GSTA1 genotype and CYP2A6 phenotype should be evaluated as markers of susceptibility to dietary carcinogens in future studies.

An assessment of surgical education.

A review of the dramatic changes in society, science and medicine that have affected the time we have available for education of students and residents. Reference is made to distance learning, educational efficiency and mental practice as concepts that may aid educators in the quest to provide the public with well trained surgeons. Surgical educators are urged to look outside of traditional models of teaching and evaluating for tools that have been successfully used by industry or business.

The effect of improving communication competency on the certifying examination of the American Board of Surgery.

BACKGROUND: Since 1991 the authors have offered a course that identifies content deficits, but only provides instruction directed at improving verbal and nonverbal behaviors. We report the outcome of this 10-year effort as success on the certifying examination of the American Board of Surgery between 1991 and 2001. METHODS: Sixteen 5-day courses were scheduled over 10 years. Participants included those who had not taken the oral examination or had failed at least once and invited senior faculty (n = 26). Sites were chosen to replicate the actual examination setting. RESULTS: There were 122 participants, with follow-up data available on 88. Success in the certifying examination after completing the course is 96 percent. CONCLUSIONS: Evaluation of communication deficits and training to improve them is strongly associated with success. Clearly, this course is effective at identifying communication behaviors that are interfering with success on the certifying examination of the American Board of Surgery.

Analysis of total meat intake and exposure to individual heterocyclic amines in a case-control study of colorectal cancer: contribution of metabolic variation to risk.

A case-control study of colorectal cancer, consisting of 157 cases and 380 controls matched by sex, ethnicity, decade of age and county of residence was performed to explore the associations between environmental exposure, metabolic polymorphisms and cancer risk. Participants were required to provide a blood sample, undergo caffeine phenotyping and complete an in-person interview that evaluated meat consumption, cooking methods and degree of doneness. A color atlas of foods cooked to different degrees of doneness was used to estimate food preparation techniques and food models were used to estimate serving portion sizes. Data was analyzed using a reference database of heterocyclic amine (HCA) exposure based on the food preferences chosen from the atlas. Data regarding individual food items cooked to different levels of doneness, as well as summary variables of foods and of food groups cooked to different degrees of doneness were also evaluated in a univariate analysis for association with colorectal cancer case status. Three measures of metabolic variation, hGSTA1 genotype, SULT1A1 genotype and the phenotype for CYP2A6 were also evaluated for possible association with colon cancer. While higher exposure to HCAs was strongly associated with colorectal cancer risk, increased consumption of five red meats cooked well done or very well done produced comparable odds ratios (OR) for colorectal cancer risk (OR=4.36, 95% CI 2.08-9.60) for the highest quartile of exposure. Similarly, individuals in the most rapid CYP2A6 phenotype quartile showed an odds ratio (OR = 4.18, 95% CI 2.03-8.90). The ORs for the low activity hGSTA1 and low activity SULT1A1 alleles were 2.0, 95% CI 1.0-3.7 and 0.6, 95% CI 0.3-1.1, respectively. Individual measures of specific HCAs provided little improvement in risk assessment over the measure of meat consumption, suggesting that exposure to other environmental or dietary carcinogens such as nitrosamines or undefined HCAs may contribute to colorectal cancer risk.

Meat intake and cooking techniques: associations with pancreatic cancer.

Heterocyclic amines (HCAs), and polycyclic aromatic hydrocarbons (PAHs), formed in temperature and time-dependent manners during cooking of meat, may increase the risk of certain cancers. As these compounds could be carcinogenic for the pancreas, we assessed meat intake, preparation methods, and doneness preferences as risk factors for exocrine pancreatic cancer. In a case-control study (cases=193, controls=674), subjects provided information on their usual meat intake and how it was cooked, e.g. fried, grilled or barbecued (BBQ), etc. Meat doneness preferences were measured using photographs that showed internal doneness and external brownness with a numerical scale. Data were analyzed with unconditional logistic regression. Odds ratios (ORs) increased with increased intake of grilled/BBQ red meat in an analysis adjusted for age, sex, smoking, education, race, and diabetes. Based on amount of BBQ meat consumed, the OR and 95% confidence interval (CI) for the fifth quintile relative to the reference group (quintiles 1 and 2) was 2.19 (1.4, 3.4). Findings were not substantively changed by further adjustment for calories, total fat, fruit and vegetables, or alcohol consumption (from a food frequency questionnaire (FFQ)). Other meat variables did not show statistically significant associations with risk nor did they substantively alter the findings for BBQ. These included total meat, processed meat, total red meat, total white meat, total broiled meat, total fried meat, or total meat cooked by means other than grilling. We conclude that grilled red meat intake is a risk factor for pancreatic cancer and that method of meat preparation in addition to total intake is important in assessing the effects of meat consumption in epidemiologic studies.