The experience with colorectal cancer screening in the Czech Republic: the detection at earlier stages and improved clinical outcomes

OBJECTIVES

Colorectal cancer (CRC) remains a major health burden. Although screening is recommended and considered beneficial, further data on its positive effects are needed for worldwide implementation.

STUDY DESIGN

The aim of our national multicentre prospective observational study was to reveal and document clinicopathological differences in CRC diagnosed by screening and presented by disease symptoms as well as assess the efficiency of the screening programme in the Czech Republic.

METHODS

Between March 2013 and September 2015, a total of 265 patients were enrolled in 12 gastroenterology centres across the Czech Republic. Patients were divided into screening and symptomatic groups and compared for pathology status and clinical characteristics. Screening was defined as a primary screening colonoscopy or a colonoscopy after a positive faecal occult blood test in an average-risk population.

RESULTS

The distribution of CRC stages was significantly (statistically and clinically) favourable in the screening group (predominance of stages 0, I and II) compared with the non-screening group (P < 0.001). The presence of distant and local metastases was significantly less frequent in the screening group than in the symptomatic group (P < 0.001). Patients in the screening group had a higher probability of radical surgery (R0) than those diagnosed based on symptoms (P < 0.001). Systemic palliative treatment was indicated in two patients in the screening group compared with 23 patients in the non-screening group (P = 0.018).

CONCLUSION

CRC diagnosed by screening disclosed less advanced clinicopathological characteristics and results in patients with a higher probability of radical surgery (R0) than diagnoses established based on symptoms, with subsequent management differing accordingly between both groups. These results advocate the implementation of a suitable worldwide screening programme.

Mutations and polymorphisms in TP53 gene--an overview on the role in colorectal cancer

A functionally normal TP53 is essential to protect organisms from developing cancer. Somatic mutations in the gene represent one of the highest recurring perturbations in human tumours, including colorectal cancer (CRC). However, the variegated phenotype of wide spectrum of somatic mutations in TP53 and the complexity of the disease prevent a straight interpretation of the mutational analysis in tumours. In addition to the presence of somatic mutations, polymorphic features of the gene may also contribute to alteration of the normal TP53 functioning and variants, mainly in the form of single nucleotide polymorphisms, can be expected to impact susceptibility to sporadic CRC. In the present study, we reviewed the potential role of alterations in the TP53 gene, both somatic mutations and inherited sequence variations, in predisposition to CRC and in the prognosis and response to therapy. The available data from association studies have mostly shown contradictory outcomes. The majority of the studies were based on limited sample sizes and focussed on a limited number of polymorphisms, with main being the rs1042522 (Arg72Pro). Thus far, there is no possible generalisation of the role of TP53 as also a predictor of therapeutic response and prognosis. The effects of TP53, and its abnormalities, on the response of tumours to cytotoxic drugs, radiation and chemoradiation are complex. However, from studies it is emerging that the inherited genetics of TP53 pathway components could be utilised to further define patient populations in their abilities to induce p53 activity in response to either DNA damaging or p53-targeted therapies.

Ornithine decarboxylase G316A genotype and colorectal cancer risk

AIM

Ornithine decarboxylase (ODC) is a modifier of adenomatous polyposis coli-dependent tumourigenesis. The G316 > A polymorphism in intron 1 of the ODC gene lies between two myc-binding domains and alters the expression of the gene to affect polyamine metabolism. This variant may be associated with recurrence of colorectal adenoma. We examined whether this variant also modified the susceptibility to sporadic colorectal cancer (CRC).

METHOD

The G316 > A variant was analysed in a large (n = 754) CRC case-controlled series of hospital patient volunteers (n = 627) in the Czech Republic, and the relationship with cancer risk was estimated by conditional logistic regression.

RESULTS

After adjusting for age and sex, G316 > A was associated with no decrease in CRC risk for either heterozygotes [odds ratio 0.98, 95% confidence interval (CI) 0.77-1.23] or rare allele homozygotes (odds ratio 0.92, 95% CI 0.61-1.37).

CONCLUSION

The G316 > A functional variant in the ODC gene is unlikely to make much impact on reducing CRC risk regardless of the reduction in risk found for the recurrence of colorectal adenoma.

Polymorphisms in metabolizing enzymes and the risk of head and neck squamous cell carcinoma in the Slavic population of the central Europe

The question of susceptibility to squamous cell carcinoma of head and neck (SCCHN) in the environmental context was addressed by analysis of functional polymorphisms in enzymes metabolizing smoke constituents and/or alcohol (CYP2A13, CYP1B1, EPHX1, NQO1, GSTM1, GSTP1, GSTT1, ADH1B and ADH1C). Case-control study of 122 age- and sex-matched pairs of subjects was performed using so far unexplored Central European Slavic population with high level of tobacco and alcohol abuse. Age-, gender-, smoking- and alcohol-adjusted logistic regression failed to demonstrate any significant association of the analyzed polymorphisms with the SCCHN risk. When interactions between potential modifiers of effect, i.e. smoking and alcohol were tested, drinkers seemed to be at lower risk than nondrinkers when carrying the heterozygous genotype Ile/Val in codon 432 of CYP1B1 (OR=0.42; 95% CI=0.21-0.83; p=0.013 vs. OR=1.02; 95% CI=0.34-2.94; p=0.977). Similarly, drinkers were at lower risk than nondrinkers when carrying the heterozygous genotype Pro/Ser in codon 187 of NQO1 (OR=0.41; 95% CI=0.19-0.88; p=0.022 vs. OR=0.96; 95% CI=0.29-3.12; p=0.948). More interestingly, drinkers carrying the rare homozygous genotype Val/Val in codon 350 of ADH1C were at significantly higher risk than nondrinkers carrying this genotype (OR=4.01; 95% CI=1.61-10.01; p=0.003 vs. OR=0.93; 95% CI=0.25-3.57; p=0.919). This result confirmed findings of previously published studies. Smoking did not significantly modify the effect of genotypes. Our data thus demonstrate that genetic susceptibility to SCCHN shall be further followed on populations with different genetic background and lifestyle.

Genotype and haplotype analysis of TP53 gene and the risk of pancreatic cancer: an association study in the Czech Republic

Pancreatic carcinoma is the fourth leading cause of cancer-related deaths in the Czech Republic, with only a minimum of patients surviving 5 years. The aetiology and molecular pathogenesis are still weakly understood. TP53 has a fundamental role in cell cycle and apoptosis and is frequently mutated in solid tumours, including pancreatic cancer. Based on the assumption that genetic variation may affect susceptibility to cancer development, the role of TP53 polymorphisms in modulating the risk of pancreatic cancer may be of major importance. We investigated four selected polymorphisms in TP53 (rs17878362:A(1)>A(2), rs1042522:G>C, rs12947788:C>T and rs17884306:G>A) in association with pancreatic cancer risk in a case-control study, including 240 cases and controls (for a total of 1827 individuals) from the Czech Republic. Carriers of the variant C allele of rs1042522 polymorphism were at an increased risk of pancreatic cancer [odds ratio (OR) 1.73; 95% confidence interval (CI) 1.26-2.39; P = 0.001]. Haplotype analysis showed that in comparison with the most common haplotype (A(1)GCG), the A(2)CCG haplotype was associated with an increased risk (OR 1.39; 95% CI 1.02-1.88; P = 0.034) and the A(1)CCG with a reduced risk (OR 0.30; 95% CI 0.12-0.76; P = 0.011) for this cancer. These results reflect previous findings of a recent association study, where haplotypes constructed on the same TP53 variants were associated with colorectal cancer risk [Polakova et al. (2009) Genotype and haplotype analysis of cell cycle genes in sporadic colorectal cancer in the Czech Republic. Hum. Mutat., 30, 661-668.]. Genetic variation in TP53 may contribute, alone or in concert with other risk factors, to modify the inherited susceptibility to pancreatic cancer, as well as to other gastrointestinal cancers.

DNA repair and cyclin D1 polymorphisms and styrene-induced genotoxicity and immunotoxicity

1-SO-adenine DNA adducts, DNA single-strand breaks (SBs), chromosomal aberrations (CAs), mutant frequency (MF) at the HPRT gene, and immune parameters (hematological and of humoral immunity) were studied in styrene-exposed human subjects and controls. Results were correlated with genetic polymorphisms in DNA repair genes (XPD, exon 23, XPG, exon 15, XPC, exon 15, XRCC1, exon 10, XRCC3, exon 7) and cell cycle gene cyclin D1. Results for biomarkers of genotoxicity after stratification for the different DNA repair genetic polymorphisms showed that the polymorphism in exon 23 of the XPD gene modulates levels of chromosomal and DNA damage, HPRT MF, and moderately affects DNA adduct levels. The highest levels of biomarkers were associated with the wild-type homozygous AA genotype. The exposed individuals with the wild-type GG genotype for XRCC1 gene exhibited the lowest CA frequencies, compared to those with an A allele (P < 0.05). Cyclin D1 polymorphism seems to modulate the number of leukocytes and lymphocytes in the analyzed subjects. The number of eosinophiles was positively associated with XPD variant C allele and negatively with XRCC1 variant A allele (P < 0.05) and XPC variant C allele (P < 0.05). Immunoglobulin IgA was positively associated with an XRCC3 variant T allele (P < 0.01) and negatively with XPC variant C allele (P < 0.05). Both C3- and C4-complement components were lower in individuals with XRCC3 CT (P < 0.05) and TT genotypes (P < 0.01). Adhesion molecules sL-selectin and sICAM-1 were associated with XPC genotype (P < 0.05). Individual susceptibility may be reflected in genotoxic and immunotoxic responses to environmental and occupational exposures to xenobiotics.

Relationship between the capacity to repair 8-oxoguanine, biomarkers of genotoxicity and individual susceptibility in styrene-exposed workers

Genotoxic effects related to exposure to styrene have been a matter of investigation for many years by employing markers of exposure, effect and susceptibility. The role of individual DNA-repair capacity in response to exposure to styrene may explain the controversial results so far obtained, but it is still scarcely explored. In the present study, we measured capacity to repair oxidative DNA damage in cell extracts obtained from 24 lamination workers occupationally exposed to styrene and 15 unexposed controls. The capacity to repair oxidative DNA damage was determined by use of a modified comet assay, as follows: HeLa cells, pre-treated with photosensitizer and irradiated with a halogen lamp in order to induce 7,8-dihydroxy-8-oxoguanine, were incubated with cell extracts from mononuclear leukocytes of each subject. The level of strand breaks reflects the removal of 7,8-dihydroxy-8-oxoguanine from substrate DNA by the enzymatic extract. In styrene-exposed subjects a moderate, non-significant increase in oxidative DNA repair was observed. Stratification for sex and smoking habit showed that unexposed males (P=0.010) and unexposed smokers (P=0.037) exhibited higher DNA-repair rates. The repair capacity did not correlate with parameters of styrene exposure and biomarkers of genotoxic effects (DNA strand breaks, N1-styrene-adenine DNA adducts, chromosomal aberrations and mutant frequencies at the HPRT locus). Significantly higher levels of DNA-repair capacity were observed in carriers of GSTM1-plus, compared to those with a deletion in GSTM1. The DNA-repair capacity was significantly lower in individuals with variant Gln/Gln genotype in XRCC1 Arg399Gln than in those with heterozygous Arg/Gln and wild-type Arg/Arg genotypes. Significantly lower repair capacity was also found in individuals with the wild-type Lys/Lys genotype in XPC Lys939Gln as compared with those homozygous for the Gln/Gln variant genotype.

DNA repair genetic polymorphisms and risk of colorectal cancer in the Czech Republic

Colorectal cancer represents a complex disease where susceptibility may be influenced by genetic polymorphisms in the DNA repair system. In the present study we investigated the role of nine single nucleotide polymorphisms in eight DNA repair genes on the risk of colorectal cancer in a hospital-based case-control population (532 cases and 532 sex- and age-matched controls). Data analysis showed that the variant allele homozygotes for the Asn148Glu polymorphism in the APE1 gene were at a statistically non-significant increased risk of colorectal cancer. The risk was more pronounced for colon cancer (odds ratio, OR: 1.50; 95% confidence interval, CI: 1.01-2.22; p=0.05). The data stratification showed increased risk of colorectal cancer in the age group 64-86 years in both individuals heterozygous (OR: 1.79; 95% CI: 1.04-3.07; p=0.04) and homozygous (OR: 2.57; 95% CI: 1.30-5.06; p=0.007) for the variant allele of the APE1 Asn148Glu polymorphism. Smokers homozygous for the variant allele of the hOGG1 Ser326Cys polymorphism showed increased risk of colorectal cancer (OR: 4.17; 95% CI: 1.17-15.54; p=0.03). The analysis of binary genotype combinations showed increased colorectal cancer risk in individuals simultaneously homozygous for the variant alleles of APE1 Asn148Glu and hOGG1 Ser326Cys (OR: 6.37; 95% CI: 1.40-29.02; p=0.02). Considering the subtle effect of the DNA repair polymorphisms on the risk of colorectal cancer, exploration of gene-gene and gene-environmental interactions with a large sample size with sufficient statistical power are recommended.

The role of various biomarkers in the evaluation of styrene genotoxicity

We evaluated our data on the occupational exposure to styrene in lamination workers. The battery of parameters included markers of external and internal exposure and biomarkers of biological effects and susceptibility. DNA repair capacities have been determined in both exposed and control groups. Styrene workplace concentration significantly correlated with styrene concentration in blood, exhaled air and urinary mandelic acid. Haemoglobin and O(6)-styrene oxide (SO)-guanine DNA adducts were significantly higher in exposed subjects as compared to controls and correlated with exposure parameters. In styrene-exposed workers 1-SO-adenine DNA adducts were detected (2.6 per 10(9) dNp), while in controls these adducts were below the detection limit. 1-SO-adenine adduct levels were affected by both acute and cumulative exposure (P=0.001, F=86.0 and P=0.017, F=59.0, respectively) and associated with cytochrome P450 2E1 (CYP2E1) polymorphisms (R(2)=0.442). Mutant frequencies (MF) at the hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus appeared to accumulate with exposure over time and were associated with glutathione S-transferase P1 (GSTP1) polymorphism. DNA repair capacity increased with the exposure, except for the group exposed to the highest styrene concentration. In this particular group, increased DNA repair capacity to remove oxidative DNA damage was found.

Association between genetic polymorphisms and biomarkers in styrene-exposed workers

A comprehensive approach to evaluate genotoxic effects induced by styrene exposure was employed in 44 hand-lamination workers in comparison with 18 unexposed controls. The acquired data on single-strand breaks in DNA (SSBs), frequency of chromosomal aberrations and HPRT mutant frequency in peripheral blood lymphocytes were compared to the results on genotyping of some of the xenobiotic-metabolising enzymes (CYP1A1, CYP2E1, epoxide hydrolase and GSTM1, GSTP1 and GSTT1). Multifactorial regression analysis indicated that SSB in DNA were significantly associated with styrene exposure and with heterozygosity in CYP2E1 (5'-flanking region and intron 6; r(2)=0.614). The frequency of chromosomal aberrations (CA), as analysed by linear multiple regression analysis, significantly correlated with years of employment (P=0.004) and with combinations of epoxide hydrolase (EPHX) genotypes (exon 3, Tyr/His and exon 4, His/Arg), where individuals with low and medium activity EPHX genotypes exhibited higher frequencies of CA than those with high activity genotypes (P=0.044, r(2)=0.563). Moderately higher HPRT mutant frequencies were detected in styrene-exposed individuals (20.2 +/- 25.8 x 10(-6)) as compared to controls (13.3 +/- 6.3 x 10(-6)), but this difference was not significant. ANOVA (in the whole set of data) revealed that mutant frequencies at the HPRT gene were significantly associated with years of employment (F=6.9, P=0.0001), styrene in blood (F=10.1, P=0.0001), and heterozygosity in CYP2E1 (intron 6; F=13.5, P=0.0008) and GSTP1 (exon 5; F=3.6, P=0.038). In conclusion, our present data suggest that analysed biomarkers of DNA damage may be modulated by polymorphic CYP2E1, EPHX and GSTP1. In our study, styrene-specific DNA and haemoglobin adducts are under investigation. Completing these data with the results of genotyping of metabolising enzymes may provide a useful tool for individual genotoxic risk assessment.

Changes in cellular immunity among workers occupationally exposed to styrene in a plastics lamination plant

BACKGROUND

Styrene is a widely used industrial chemical. Immune and hematological parameters were examined in 29 hand laminators and sprayers exposed to styrene for an average of 14 years and in 19 in-factory unexposed controls. The workers performed hand lamination procedures in a production area with an average area airborne styrene level of 139.5 mg/m(3). Mean concentration of styrene in the blood of exposed workers was 945.7 microg/L and the mean styrene in exhaled air was 38.8 microg/L.

METHODS

Parameters of internal and external exposure, immune function assays, immunoglobulins, acute phase reactants and hematology were evaluated in exposed and non-exposed populations.

RESULTS

Using multifactorial analysis of variance we found a significant decrease in proliferation of lymphocytes stimulated by Concanavalin A but not by pokeweed mitogen (PWM) in workers occupationally exposed to styrene. Proliferative response to PWM was significantly correlated with the levels of styrene in blood. Phagocytic activity of monocytes, levels of IgG, IgA, IgM, IgE and alpha-2-macroglobulin in serum were indistinguishable in the two groups. The population exposed to styrene had increased levels of C4-component of complement. Levels of C3-component of complement were positively correlated with duration of exposure. A significant elevation in the percentage and number of monocytes and a significantly decreased number of lymphocytes were seen in exposed workers. Styrene concentrations in both blood and exhaled air were associated with decreased percentage of large granular lymphocytes.

CONCLUSIONS

These results suggest immune alterations of cell-mediated immune response of T-lymphocytes and imbalance in leucocyte subsets in peripheral blood of workers exposed to styrene.

32P-postlabeling of DNA adducts of styrene-exposed lamination workers

Lamination workers are exposed to high concentrations of styrene. A postlabeling method was developed for the detection of styrene-specific DNA adducts of the workers. To synthesize a standard, styrene oxide was reacted with 2'-deoxyguanosine 3'-monophosphate (dGMP) and the O6-dGMP-adduct was isolated and characterized. The human samples were assayed by the nuclease P1 version of the 32P-postlabeling technique, using magnet transfer of the adducts in chromatography. The human samples were spiked with the standards to ensure identification and quantitation. In lamination workers the O6-adducts, adjusted for adduct recovery, were detected at a level of 5 adducts/10(8) nucleotides, over five times the level in the controls.

Polycyclic aromatic hydrocarbon-DNA adducts in white blood cells and urinary 1-hydroxypyrene in foundry workers

In an ongoing comprehensive evaluation of biological markers, workers in or near an iron foundry with varying exposure to polycyclic aromatic hydrocarbons (PAH) were analyzed for molecular response to this exposure. Exposure to benzo(a)pyrene, determined by personal monitors worn by the workers (2 to 60 ng/m3), was considerably lower than in a previous study at this foundry (< 50 to 200 ng/m3) (F.P. Perera et al., Cancer Res., 48: 2288-2291, 1988). Two biomarkers, 1-hydroxypyrene in urine measured by high-performance liquid chromatography with fluorescence detection (a measure of internal dose) and PAH-DNA adducts in WBC measured by immunoassay (a measure of biologically effective dose) were assessed to demonstrate their relationship to the lowest exposures yet analyzed in foundry workers. In addition, these markers were analyzed for dose response and interindividual variability. Cigarette smoking, but not age or charbroiled food, influenced the level of 1-hydroxypyrene but not PAH-DNA adducts. When workers were classified into three exposure categories (low, medium, and high), mean 1-hydroxypyrene levels were 2.7, 1.8, and 3.6 mumol/mol creatinine, respectively. Comparisons by analysis of variance showed a significant difference between the groups after controlling for smoking (P = 0.02), but a trend test using multivariate linear regression analysis was not significant (r = 0.27; P = 0.07). Substantial interindividual variation was demonstrated by the 19- to 20-fold range in the values within each of the three exposure groups.(ABSTRACT TRUNCATED AT 250 WORDS)