Skip Navigation


Carcinogenesis Advance Access originally published online on February 2, 2007
Carcinogenesis 2007 28(7):1426-1429; doi:10.1093/carcin/bgm022
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
28/7/1426    most recent
bgm022v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (1)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Gunter, M. J.
Right arrow Articles by Sinha, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gunter, M. J.
Right arrow Articles by Sinha, R.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Published by Oxford University Press 2007.

Leukocyte polycyclic aromatic hydrocarbon–DNA adduct formation and colorectal adenoma

Marc J. Gunter1,2,*,{dagger}, Rao L. Divi3,{dagger}, Martin Kulldorff4, Roel Vermeulen1,5, Kathryn J. Haverkos3, Maryanne M. Kuo3, Paul Strickland6, Miriam C. Poirier3, Nathaniel Rothman1 and Rashmi Sinha1

1 Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Division of Health and Human Services, Bethesda, MD 20852, USA
2 Department of Epidemiology and Population Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
3 Carcinogen-DNA Interactions Section, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Division of Health and Human Services, Bethesda, MD 20892, USA
4 Department of Ambulatory Care and Prevention, Harvard Medical School and Harvard Pilgrim Health Care, Boston, MA 02115, USA
5 Division of Environmental Epidemiology, Institute of Risk Assessment Sciences, University of Utrecht, Utrecht, NL-3508 TD, The Netherlands
6 Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA

* To whom correspondence should be addressed. Tel: +718 430 3089; Fax: +718 430 8780; Email: mgunter{at}aecom.yu.edu


   Abstract
Top
 Abstract
Introduction
 Materials and methods
 Results
 Discussion
 References
 
Consumption of charbroiled red meat and meat-derived polycyclic aromatic hydrocarbons (PAHs) has been associated with risk of colorectal adenoma, a precursor of colorectal cancer. Furthermore, leukocyte PAH–DNA adduct levels have been demonstrated to increase in response to charbroiled red meat intake but to date there have been no studies that have investigated the relationship between leukocyte PAH–DNA adduct levels and risk of colorectal adenoma. We investigated the relation of leukocyte PAH–DNA adduct formation and colorectal adenoma in a clinic-based case–control study of colorectal adenomas. The study comprised 82 cases of colorectal adenoma and 111 polyp-free controls, none of whom were current smokers. Leukocyte PAH–DNA adducts were measured by a sensitive chemiluminescence immunoassay using an antiserum elicited against DNA modified with (±)-7ß,8{alpha}-dihydroxy-9{alpha},10{alpha}-epoxy-7,8,9,10-tetrahydro-benzo[a]pyrene that recognizes several PAHs bound to human DNA. Leukocyte PAH–DNA adduct levels were higher among colorectal adenoma cases (median, 1.4 adducts per 108 nucleotides) than polyp-free controls (median, 1.2 adducts per 108 nucleotides) (P = 0.02). There was a positive association between PAH–DNA adduct level and adenoma prevalence: each unit increase in PAH–DNA adduct level (per 108 nucleotides) was associated with an odds ratio (OR) of 1.5 [95% confidence interval (CI), 1.1–2.2]. In addition, a comparison of the lowest quartile for PAH–DNA adduct level with the highest quartile yielded an OR of 2.8 (95% CI, 1.2–6.5; Ptrend = 0.048) for risk of colorectal adenoma. These data support a link between PAH exposure and colorectal adenoma.

Abbreviations: BP, benzo[a]pyrene; BPDE, 7ß,8{alpha}-dihydroxy-9{alpha},10{alpha}-epoxy-7,8,9,10-tetrahydro-benzo[a]pyrene; BPdG, 10ß-(deoxyguanosin-N2-yl)-7ß,8{alpha},9{alpha}-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene; CI, confidence interval; CIA, chemiluminescence immunoassay; OR, odds ratio; PAH, polycyclic aromatic hydrocarbon


   Introduction
Top
 Abstract
 Introduction
Materials and methods
 Results
 Discussion
 References
 
There is mounting evidence to implicate the consumption of meat in colorectal carcinogenesis, and several hypotheses have been advanced to account for this association (1). Recently, studies focused on meat-cooking methods have reported positive associations between intake of charbroiled red meat and colorectal adenoma, a precursor of colorectal cancer (2,3). Furthermore, dietary consumption of benzo[a]pyrene (BP), a marker for polycyclic aromatic hydrocarbons (PAHs) that are formed in meat exposed to pyrolytic temperatures (for example during charbroiling), was associated with colorectal adenoma in three separate populations (3–5).

Given the potential relationship between charbroiled red meat and meat-derived PAH consumption with colorectal adenoma, as determined using dietary questionnaire instruments, a logical progression would be to relate a biological marker of PAH exposure with colorectal adenoma risk. Dietary intake of BP from charbroiled meat may increase levels of leukocyte PAH–DNA adducts (6–8) but to date no studies have investigated the association between leukocyte PAH–DNA adduct levels and risk of colorectal adenoma. DNA adduct levels effectively serve as an integrated measure of both exposure and metabolism, reflecting intake of the parent compound as well as biotransformation, DNA repair capacity and cell turnover; whereas the dietary questionnaire reflects only exposure. A positive association between PAH-induced DNA damage and colorectal adenoma, in a study where smoking has been eliminated as a contributing factor, would not only support the hypothesis that elevated exposure to PAHs is related to colorectal carcinogenesis, thus complementing the questionnaire-based dietary assessment, but also could potentially serve to validate PAH–DNA adduct formation as a biomarker of colorectal adenoma risk.

Here we investigated the relation of leukocyte PAH–DNA adduct level, measured by an anti-7ß,8{alpha}-dihydroxy-9{alpha},10{alpha}-epoxy-7,8,9,10-tetrahydro-benzo[a]pyrene (BPDE)–DNA chemiluminescence immunoassay (CIA) (9,10) that recognizes several PAHs bound to human DNA (11), and colorectal adenoma risk among participants of a case–control study in which dietary intake of BP had been previously found to be associated with colorectal adenoma risk (3).


   Materials and methods
Top
 Abstract
 Introduction
 Materials and methods
Results
 Discussion
 References
 
Study population
Details of this case–control study have been described previously (2). Briefly, cases were individuals diagnosed with colorectal adenoma at sigmoidoscopy or colonoscopy between April 1994 and September 1996 at the National Naval Medical Center (Bethesda, MD). All adenomas were histologically confirmed. Controls were subjects free of polyps of the distal colorectum at sigmoidoscopy during the same time period. To be eligible for the study, cases and controls were required to be residents of the study area, between ages 18 and 74 years, and never diagnosed with Crohn’s disease, ulcerative colitis or cancer, except non-melanoma skin cancer. The study was approved by the Institutional Review Boards of the National Cancer Institute and the National Naval Medical Center, Bethesda, MD, and all participants provided informed consent.

The participation rates were 84% for the cases (241 of the 289 eligible cases identified) and 74% for the controls (231 of the 314 eligible controls). The main reason for non-participation was subject refusal (12% of cases and 21% of controls), followed by illness (3% of cases and 4% of controls), and other reasons (1% of cases and 1% of controls). After excluding five participants with implausible dietary data, 93 with a history of previous adenomas, 15 who reported being smokers at the time of sigmoidoscopy or colonoscopy and 166 with an inadequate amount of DNA available, the study consisted of the remaining 82 cases and 111 controls.

Sample procurement and DNA preparation
Blood was obtained, from the study participants and centrifuged to obtain plasma (top), buffy coat (nucleated cells—middle) and erythrocytes (bottom) as described previously (9). Buffy coat samples, containing the leukocytes, were retrieved and stored frozen at –80°C until DNA isolation was performed. DNA was prepared as described by Daly et al. (12). Briefly, nuclei were collected by centrifugation of buffy coat samples and lysed in sucrose buffer. The nuclear pellet was re-suspended in neutral Tris–HCl buffer, incubated at 65°C for 30 min and extracted with 2 ml chloroform. Following centrifugation, the aqueous DNA-containing upper phase was transferred to a fresh tube, and the DNA was precipitated in ethanol and spooled. The spooled DNA was washed in 70% ethanol and allowed to dry at room temperature for 20 min. In the absence of visible spooled material, DNA was recovered by centrifugation. DNA was re-suspended in 50–400 µl of 10 mM Tris–HCl, 1 mM ethylenediaminetetraacetic acid, pH 7.4, by incubation at 60°C for 8–16 h. DNA was stored, following aliquoting, at –80°C. DNA purity was checked by electrophoresis on ethidium bromide-containing agarose minigels using Tris–Borate–ethylenediaminetetraacetic acid buffer (13). Molecular weight markers (100 bp ladder, Gibco BRL, Gaithersburg, MD) were also included on each gel. Bands were visualized on a UV transilluminator, and gels photographed using a Kodak DC40 digital camera.

Quantification of PAH–DNA adducts
Analysis of PAH–DNA adduct levels in DNA isolated from buffy coat samples was performed as described previously using the BPDE–DNA CIA (9), with slight modifications. Microtiter plates for the CIA were 96-well high-binding luminescent immunoassay (LIA) plates (Greiner Bio-one, Longwood, FL). The CIA-specific reagents, including I-Block (0.25% casein) and CDP-Star with Emerald II, were obtained from PE Applied Biosystems (Foster City, CA). Biotinylated anti-rabbit IgG was from Jackson ImmunoResearch Laboratories (West Grove, PA). Reacti-Bind DNA coating solution was from Pierce Biotechnology (Rockford, IL).

Microtiter plates were coated for 48 h with 100 pg of sonicated calf thymus DNA or BPDE–DNA (calf thymus DNA modified to 0.33% with BPDE), in 0.1 ml of Reacti-Bind DNA coating solution (Pierce Biotechnology) at room temperature for 48 h, and stored at –20°C until further use. On the day of analysis plates were washed three times with phosphate-buffered saline–Tween-20 containing 0.05% NaN3 (Sigma, St Louis, MO) using an automated plate washer (Ultrawash Plus, Dynex Technologies, Guernsey, UK). All subsequent washes were performed in this fashion. Plates were first incubated with I-Block in phosphate-buffered saline–Tween-20 containing 0.05% NaN3 for 60 min at 37°C and washed (as above). Biological sample DNA, or standard BPDE–DNA, was sonicated (20 s at 20% amplitude using an Ultrasonic Processor, Sonics & Materials, Newtown, CT), denatured by boiling for 4 min and cooled for 10 min on ice, before mixing with an equal volume of BPDE–DNA antiserum [rabbit #31, bleed #8/16/78 (10)] diluted 1:3 000 000 in I-Block. The mixture was then transferred to the microtiter plate where each sample was assayed in triplicate experimental wells and one control well. Serial dilutions of the standard BPDE–DNA [modified to 10ß-(deoxyguanosin-N2-yl)-7ß,8{alpha},9{alpha}-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPdG) adduct per 106 nucleotides], diluted in carrier calf thymus DNA, were prepared such that each well contained an equal quantity of DNA but 0–16 fmol BPdG adduct per well. Plates were incubated with specific BPDE–DNA antiserum, and standard or sample DNA, for 90 min at 37°C, washed and incubated again with biotinylated anti-rabbit antibody (1:2500) in I-Block solution for 90 min at 37°C. After washing, plates were incubated with streptavidin alkaline phosphatase (Avidix–AP = 1:5000) in I-Block solution at room temperature for 60 min and washed with phosphate-buffered saline–Tween-20, distilled water and Tris buffer (20 mM Tris containing 1 mM MgCl2, pH 9.5), before adding CDP-Star-Emerald II solution and incubating at room temperature for 20 min and at 4°C for 15 h. Luminescence was measured using a TR717 Microplate Luminometer (PE Applied Biosystems).

A BPDE–DNA standard curve was assayed on each plate and the 50% inhibition for BPdG adducts was at 1.51 ± 0.08 fmol BPdG per well (mean ± SE, n = 27). The lower limit of detection, when using 10 µg DNA, was 0.4 adducts per 108 nucleotides. The majority of the study samples were assayed at 10 µg DNA per well but for ~15% of the samples the quantity of DNA varied from 7 to 13 µg per well. In all, 236 samples from 193 individuals were assayed, and 30 of these samples (10 cases and 20 controls) were below the limit of detection of the BPDE–DNA CIA. For computational purposes, non-detectable samples were given a value of half the limit of detection, or 0.2 adducts per 108 nucleotides.

In addition to the standard curve, each assay plate contained a positive and negative quality control sample and both samples were assayed on each of the 27 plates. These consisted of DNA samples obtained from MCL-5 cells exposed on one occasion to 0 or 4 µM BP for 24 h. Each assay plate contained aliquots of the exposed (positive) and unexposed (negative) quality control DNA samples. The positive quality control sample gave a mean percent inhibition value of 60.2 ± 4.8 (mean ± SD, n = 27) that corresponds to 7.2 ± 1.0 BPdG adducts per 108 nucleotides. Thus, the overall coefficient of variation for the assay using biological sample DNA was 14.3%. In addition, of the 236 samples analyzed, 38 were assayed twice (on separate days and on separate plates, as described previously) (9) and the correlation between the two assays was very high (r2 = 0.95).

Statistical analysis
Human samples were assayed coded, and the codes were revealed only after completion of the BPDE–DNA CIA analyses. Unconditional logistic regression was used to estimate the association of leukocyte PAH–DNA adduct level with risk of colorectal adenoma. Analyses were performed using PAH adduct level expressed as both a continuous variable and a categorical variable, in which the observed adduct values were categorized into quartiles based upon the distribution among the control subjects. Odds ratios (ORs) were adjusted for age and gender. Additional adjustments for reason for screening (routine or other), physical activity level, use of non-steroidal anti-inflammatory drugs, consumption of red meat, charbroiled red meat, BP, total fat, saturated fat, fruits, vegetables, fiber or alcohol, as well as for education, race, body mass index, bowel movement frequency, season of blood draw and family history of colorectal cancer, did not substantially alter the findings (cause a 10% or greater change in the OR) and were therefore not included as covariates in the multivariate analysis. The association between leukocyte PAH–DNA adduct formation and intake of dietary BP was investigated using Spearman's rank correlation coefficient. The relation of combined leukocyte PAH adduct and dietary BP intake with colorectal adenoma was assessed by creating a new, unitless variable that was the sum of these measures. Specifically, the continuous variables for leukocyte PAH adduct and dietary BP were standardized relative to their means and standard deviations among the controls [(variable–mean)/SD] and were then added together to create a combined variable. The combined variable was also categorized into quartiles according to its distribution among the controls. The association of PAH adduct levels as a continuous variable with colorectal adenoma was also investigated within strata of dietary BP intake, where BP intake levels were categorized as high and low, with the median value among the controls serving as cut-point. All statistical tests were two-sided and a P value < 0.05 was considered statistically significant.


   Results
Top
 Abstract
 Introduction
 Materials and methods
 Results
Discussion
 References
 
In this study, we have chosen to take a one-time ‘opportunity’ blood sample with the assumption that this should represent relatively constant PAH exposure and constant metabolic processing in a particular individual. As the subjects were middle class American individuals, not currently exposed occupationally to PAHs, they were considered to have relatively stable PAH exposures. Among the 236 leukocyte DNA samples (from 193 individuals) assayed by BPDE–DNA CIA, 30 were non-detectable and were therefore assigned a value halfway between 0 and limit of detection for the analysis. Each sample was assayed in one microtiter plate in which three experimental wells and one well coated with calf thymus DNA contained a single sample. There was a large overlap in PAH–DNA adduct values among samples from individuals who were cases and those were controls, and the data are shown in Figure 1.


Figure 1
View larger version (10K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Fig. 1. Box-and-whisker plots illustrating distribution of leukocyte DNA–PAH adduct levels (per 108 nucleotides) among colorectal adenoma cases and polyp-free controls. Upper and lower edges of the boxes represent the 75th and 25th percentiles, respectively. The median value is indicated by the horizontal line within each box. Outliers, defined as observations >1.5 times the interquartile range, are represented by closed dots. Mean (±SD) values are 1.5 (0.8) adducts per 108 nucleotides and 1.2 (0.8) adducts per 108 nucleotides, respectively. Median values are 1.4 adducts per 108 nucleotides and 1.2 adducts per 108 nucleotides for cases and controls, respectively. P for the difference in median values for cases and controls is 0.02 (as determined by the Wilcoxon signed rank sum test).

 
Among the individuals from whom leukocyte PAH–DNA adducts were measured, cases and controls did not differ in terms of age, gender or body mass index (Table I). Compared with the control group, fewer of the cases reported ever use of non-steroidal anti-inflammatory drugs (P = 0.01). In addition, cases reported greater consumption of red meat (P = 0.02) and well-done red meat (P = 0.01) and had higher intakes of BP from meat (P = 0.01). These characteristics were concordant with the overall study population as reported previously (2,4). Median leukocyte PAH–DNA adduct levels were statistically significantly higher among cases (1.4 per 108 nucleotides) compared with controls (1.2 per 108 nucleotides) (P = 0.02) as illustrated in Figure 1. There was a positive association between leukocyte PAH–DNA adduct level and adenoma prevalence: OR = 1.5 [95% confidence interval (CI), 1.1–2.2] for each unit increase in PAH–DNA adduct per 108 nucleotides after controlling for age and gender. Furthermore, compared with individuals in the lowest quartile for PAH–DNA adduct level, those in the highest quartile had a statistically significant increased risk of colorectal adenoma: OR = 2.8 (95% CI, 1.2–6.5; Ptrend = 0.048) (Table II).


View this table:
[in this window]
[in a new window]

  		Table I. Selected baseline characteristics of the study population: median values (interquartile range) for demographics, dietary parameters and PAH–DNA adducts

 


View this table:
[in this window]
[in a new window]

  		Table II. Association between leukocyte PAH–DNA adducts and colorectal adenoma

 
Leukocyte PAH–DNA adduct levels and intake of BP were not correlated among the control individuals (r = –0.03). The combination of leukocyte PAH–DNA adduct levels and BP intake did not yield risk estimates greater than the associations for each of the variables individually (highest quartile versus lowest quartile, OR = 2.5; 95% CI, 1.0–5.8). However, the association of leukocyte PAH–DNA adduct with colorectal adenoma was stronger among individuals with lower estimated intake of dietary BP (OR = 1.8; 95% CI, 1.1–2.8) than those with higher estimated BP intake (OR = 1.2; 95% CI, 0.8–1.7) but there was no evidence for a statistically significant interaction (P-interaction = 0.22) (data not shown).


   Discussion
Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
References
 
We have shown previously that consumption of meat-derived BP is positively associated with colorectal adenomas in this study population (3). We have also demonstrated previously that dietary intake of BP from charbroiled meat may increase levels of leukocyte PAH–DNA adducts (6–8). Here we report a statistically significant link between levels of leukocyte PAH–DNA adducts and colorectal adenoma prevalence in cases and controls, none of whom were current smokers.

A large body of evidence links DNA adduct formation to the causal pathway of chemical-induced tumorigenesis in experimental model systems. There is, however, much less data linking DNA adduct formation and cancer risk in the human population. Evaluation of PAH–DNA adducts, determined by immunohistochemistry in human liver biopsies, showed a 4-fold increased risk of hepatocellular carcinoma in individuals with high PAH–DNA adduct levels compared with those with low PAH–DNA adduct levels (14). Additional studies measuring PAH–DNA adduct levels in human white blood cells have shown 2-fold higher adduct levels in smoking lung cancer cases compared with smoking controls (15–17), possibly supporting the notion that, among individuals with similar smoking habits, those forming the highest numbers of DNA adducts are more likely to develop lung tumors. The current study is unique in that it addresses the role of PAH–DNA adducts in relation to colorectal adenoma. The positive association between leukocyte PAH–DNA adduct levels and colorectal adenoma demonstrated in this investigation supports the notion that PAH exposure from charbroiled meat or other sources is associated with colorectal carcinogenesis and that DNA adduct formation contributes to human cancer risk.

We found positive relationships between PAH–DNA adduct levels and colorectal adenoma, and previously between BP ingestion, estimated by questionnaire, and colorectal adenoma (2). However, on an individual basis there was no correlation between BP intake and PAH–DNA adduct formation (Spearman's rank correlation coefficient, r = –0.03). This lack of correlation may reflect differences in the temporal span of these two measurements. Dietary BP consumption, estimated by questionnaire, reflects habitual consumption over the previous ~12 months, whereas, as noted above, PAH–DNA adduct levels are largely reflective of consumption during the previous week (7). Therefore, an individual who habitually consumes high quantities of meat-derived BP but by chance abstained from meat a few days before the blood draw would be classified as a high consumer by the dietary questionnaire but a low consumer by the PAH–DNA adduct measurement. In an attempt to better classify individuals in terms of their PAH exposure, we combined leukocyte PAH–DNA adduct level and dietary BP consumption. We have reported previously a positive association between BP intake and colorectal adenoma in this study population, such that individuals in the highest category of consumption had a statistically significant OR of 2.8 for colorectal adenoma compared with those in the lowest category (4). The combination of PAH–DNA adduct levels with BP did not yield a stronger positive association than either measure alone suggesting that measuring leukocyte PAH–DNA adduct levels does not contribute further information than that already gained by the questionnaire-based assessment. However, the association of PAH–DNA adducts and colorectal adenoma was more apparent among individuals that reported lower consumption of dietary BP. This suggests that among individuals that consume low levels of dietary BP, the measurement of PAH–DNA adducts may provide additional information that might be useful in identifying those who are susceptible to colorectal neoplasia. Further exploration of these apparent differences in a larger population would be of interest.

Potential sources of bias in our study include undetected right-sided adenomas among the control population since only individuals with a confirmed left-sided adenoma underwent colonoscopy. However, after restriction of our analysis to left-sided adenomas only, the risk estimates remained essentially unchanged indicating that the influence of any misclassified controls was minimal. The majority of the study participants were white-collar workers employed or retired from the USA Navy; therefore, additional occupational exposures to high levels of PAHs appear to be unlikely. In addition, the exclusion of current smokers from this study enhances the likelihood that much of the PAH–DNA adduction measured here was derived from dietary sources. In an earlier study conducted among firefighters, a population with consistently high exposure to PAHs, it was found that recent intake of charbroiled meat was associated with elevated white blood cell PAH–DNA adduct levels, whereas recent occupational exposure to burning matter was not (7). However, it is possible that other PAH sources, in addition to charbroiled meat, contributed to the PAH adduct levels found in these individuals. Indeed, in an analysis of major foods consumed in the USA, it was found that meat contributed only 19% to the total BP in the diet and whereas the highest concentrations of BP were found in charbroiled meat, other foods such as cereals and green leafy vegetables were also significant sources (4,18). Finally, although blood samples were obtained after the colonoscopic or sigmoidoscopic procedure, we feel that disease bias is unlikely since following diagnosis of an adenoma, there was no counseling regarding changing of dietary habits (e.g. meat-cooking practices).

In summary, measurement of leukocyte PAH–DNA adduct levels reveals primarily recent PAH exposures, which in this population are likely to be of dietary origin and possibly related to consumption of charbroiled meat. Our finding that elevated PAH–DNA adduct levels are positively associated with colorectal adenoma risk contributes to the growing awareness that PAHs are etiologically relevant to colorectal carcinogenesis.


   Footnotes
 
{dagger} These authors contributed equally to this study. Back


   Acknowledgments
 
We are grateful to Jane Curtin of Information Management Systems for assistance in data management for this study, and Jackie King of Bioreliance for sample handling. This work has been supported in part by the Intramural Program of the National Institutes of Health (National Cancer Institute, Center for Cancer Research).

Conflict of Interest Statement: None declared.


   References
Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 

  1. Cross AJ, et al. Meat-related mutagens/carcinogens in the etiology of colorectal cancer. Environ. Mol. Mutagen. (2004) 44:44–55.[CrossRef][ISI][Medline]
  2. Sinha R, et al. Well-done, grilled red meat increases the risk of colorectal adenomas. Cancer Res. (1999) 59:4320–4324.[Abstract/Free Full Text]
  3. Gunter MJ, et al. Meat intake, cooking-related mutagens and risk of colorectal adenoma in a sigmoidoscopy-based case-control study. Carcinogenesis (2005) 26:637–642.[Abstract/Free Full Text]
  4. Sinha R, et al. Dietary benzo[a]pyrene intake and risk of colorectal adenoma. Cancer Epidemiol. Biomarkers Prev. (2005) 14:2030–2034.[Abstract/Free Full Text]
  5. Sinha R, et al. Meat, meat cooking methods and preservation, and risk for colorectal adenoma. Cancer Res. (2005) 65:8034–8041.[Abstract/Free Full Text]
  6. Rothman N, et al. Formation of polycyclic aromatic hydrocarbon-DNA adducts in peripheral white blood cells during consumption of charcoal-broiled beef. Carcinogenesis (1990) 11:1241–1243.[Abstract/Free Full Text]
  7. Rothman N, et al. Contribution of occupation and diet to white blood cell polycyclic aromatic hydrocarbon-DNA adducts in wildland firefighters. Cancer Epidemiol. Biomarkers Prev. (1993) 2:341–347.[Abstract]
  8. Kang DH, et al. Interindividual differences in the concentration of 1-hydroxypyrene-glucuronide in urine and polycyclic aromatic hydrocarbon-DNA adducts in peripheral white blood cells after charbroiled beef consumption. Carcinogenesis (1995) 16:1079–1085.[Abstract/Free Full Text]
  9. Divi RL, et al. Highly sensitive chemiluminescence immunoassay for benzo[a]pyrene-DNA adducts: validation by comparison with other methods, and use in human biomonitoring. Carcinogenesis (2002) 23:2043–2049.[Abstract/Free Full Text]
  10. Poirier MC, et al. Quantitation of benzo(a)pyrene-deoxyguanosine adducts by radioimmunoassay. Cancer Res. (1980) 40:412–416.[Abstract/Free Full Text]
  11. Weston A, et al. Derivative fluorescence spectral analysis of polycyclic aromatic hydrocarbon-DNA adducts in human placenta. Chem. Res. Toxicol. (1989) 2:104–108.[CrossRef][ISI][Medline]
  12. Daly AK, et al. CYP2D6 multiallelism. Meth. Enzymol. (1996) 272:199–210.[ISI][Medline]
  13. Fritsch EF, et al. Molecular Cloning: A Laboratory Manual. (1989) U.S: Cold Spring Harbor Laboratory Press.
  14. Chen SY, et al. Polycyclic aromatic hydrocarbon-DNA adducts in liver tissues of hepatocellular carcinoma patients and controls. Int. J. Cancer (2002) 99:14–21.[CrossRef][ISI][Medline]
  15. Tang D, et al. A molecular epidemiological case-control study of lung cancer. Cancer Epidemiol. Biomarkers Prev. (1995) 4:341–346.[Abstract]
  16. Tang D, et al. Association between carcinogen-DNA adducts in white blood cells and lung cancer risk in the physicians health study. Cancer Res. (2001) 61:6708–6712.[Abstract/Free Full Text]
  17. Bak H, et al. Bulky DNA adducts as risk indicator of lung cancer in a Danish case-cohort study. Int. J. Cancer (2006) 118:1618–1622.[CrossRef][ISI][Medline]
  18. Kazerouni N, et al. Analysis of 200 food items for benzo[a]pyrene and estimation of its intake in an epidemiologic study. Food Chem. Toxicol. (2001) 39:423–436.[CrossRef][ISI][Medline]
Received December 4, 2006; revised January 19, 2007; accepted January 23, 2007.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?



This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
28/7/1426    most recent
bgm022v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (1)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Gunter, M. J.
Right arrow Articles by Sinha, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gunter, M. J.
Right arrow Articles by Sinha, R.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?