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Xifeng Wu

Publications and source records attributed to Xifeng Wu.

At least 73 records · Page 4Linked to original sources
PubMed2004

Role and limitations of epidemiology in establishing a causal association.

Cancer risk assessment is one of the most visible and controversial endeavors of epidemiology. Epidemiologic approaches are among the most influential of all disciplines that inform policy decisions to reduce cancer risk. The adoption of epidemiologic reasoning to define causal criteria beyond the realm of mechanistic concepts of cause-effect relationships in disease etiology has placed greater reliance on controlled observations of cancer risk as a function of putative exposures in populations. The advent of molecular epidemiology further expanded the field to allow more accurate exposure assessment, improved understanding of intermediate endpoints, and enhanced risk prediction by incorporating the knowledge on genetic susceptibility. We examine herein the role and limitations of epidemiology as a discipline concerned with the identification of carcinogens in the physical, chemical, and biological environment. We reviewed two examples of the application of epidemiologic approaches to aid in the discovery of the causative factors of two very important malignant diseases worldwide, stomach and cervical cancers. Both examples serve as paradigms of successful cooperation between epidemiologists and laboratory scientists in the pursuit of the understanding of cancer etiology.

Carcinogens↗
PubMed2004

Dietary carotenoids and genetic instability modify bladder cancer risk.

In vitro and in vivo studies have shown that carotenoid supplementation is associated with decreased DNA damage, but the role of dietary carotenoids in cancer risk remains controversial because epidemiologic studies have yielded conflicting results. Limited data exist regarding the role of dietary carotenoids in the context of constitutional genetic instability in cancer risk. This case-control study estimated dietary carotenoid intake [microg/(kJ . d)] from a FFQ for 423 patients with bladder cancer and 467 healthy controls, and quantified baseline and benzo[a]pyrene diol epoxide (BPDE)- and gamma-radiation-induced DNA damage in the peripheral blood lymphocytes using the comet assay. Overall, intake of total carotenoids was lower (P < 0.01) for bladder cancer cases (mean +/- SD: 1273.4 +/- 688.9) compared with healthy controls (1501.3 +/- 791.5). When categorized into quartiles, there was an inverse association between increasing levels of carotenoid intake and bladder cancer risk with greatest protective effect [odds ratio (OR) = 0.56, 95% CI, 0.37-0.85] in the quartile with the highest level of intake. Baseline and mutagen-induced DNA damage was significantly higher in cases than in controls; when analyzed jointly with carotenoid intake, high DNA damage and low carotenoid intake were associated with the highest risk. For example, with high baseline DNA damage and low total carotenoid intake, the OR was 3.08 (95% CI, 1.64-5.77); with high baseline DNA damage and high total carotenoid intake, the risk was somewhat attenuated (OR = 2.49, 95% CI, 1.28-4.84). The risk was decreased further for low baseline DNA damage and low total carotenoid intake (OR = 2.18; 95% CI, 1.13-4.22). This study provides evidence of a preventive role for carotenoids in bladder cancer, and these data may have important implications for cancer prevention, especially for individuals susceptible to DNA damage.

Carotenoids↗
PubMed2004

Comparison of haplotype inference methods using genotypic data from unrelated individuals.

OBJECTIVE: Haplotypes are gaining popularity in studies of human genetics because they contain more information than does a single gene locus. However, current high-throughput genotyping techniques cannot produce haplotype information. Several statistical methods have recently been proposed to infer haplotypes based on unphased genotypes at several loci. The accuracy, efficiency, and computational time of these methods have been under intense scrutiny. In this report, our aim was to evaluate haplotype inference methods for genotypic data from unrelated individuals. METHODS: We compared the performance of three haplotype inference methods that are currently in use--HAPLOTYPER, hap, and PHASE--by applying them to a large data set from unrelated individuals with known haplotypes. We also applied these methods to coalescent-based simulation studies using both constant size and exponential growth models. The performance of these methods, along with that of the expectation-maximization algorithm, was further compared in the context of an association study. RESULTS: While the algorithm implemented in the software PHASE was found to be the most accurate in both real and simulated data comparisons, all four methods produced good results in the association study.

Algorithms↗
PubMed2003

Sulfotransferase 1A1 (SULT1A1) polymorphism and bladder cancer risk: a case-control study.

Sulfotransferases (SULT) catalyze both the bioactivation and detoxification of a wide range of promutagens and procarcinogens. SULT1A1 appears to be an important phenol SULT because of its abundance and distribution in many tissues and wide substrate specificity. The SULT1A1 gene possesses a G-->A polymorphism that results in an Arg to His amino acid substitution, and the His(213) allele has been shown to have low activity and low thermal stability. Because of its functional role and published data showing the influence of Arg213His polymorphism on the risk of some cancers, we hypothesized that the His(213) allele of the SULT1A1 gene may modify bladder cancer risk. To test this hypothesis, we determined the SULT1A1 Arg213His genotypes in 384 incident bladder cancer patients and 386 healthy frequency-matched controls. A comprehensive epidemiologic interview was conducted on all participants to collect personal information, such as demographics and smoking status. The Arg/His and His/His genotypes were more common in the controls than the cases (P=0.035), resulting in a His(213) allele frequency of 35.0% in controls and 28.8% in cases. When individuals with the His(213) allele genotypes (Arg/His+His/His) were combined and compared to individuals with the Arg/Arg genotype, we observed a statistically significant reduced risk of bladder cancer (OR=0.72; 95% CI 0.54-0.97). When we examined the data by gender, there was a statistically significant reduced risk of bladder cancer only in women (OR=0.42; 95% CI 0.23-0.78) and not in men (OR=0.84; 95% CI 0.60-1.19) with the His(213) genotypes. In addition, there was a reduced bladder cancer risk in never smokers (OR=0.59; 95% CI 0.36-0.98) with the His(213) allele genotypes, but not in former (OR=0.82; 95% CI 0.54-1.25) or current smokers (OR=0.68; 95% CI 0.29-1.58). The His(213) allele genotypes also appeared to provide some protective benefit for current and former smokers, as compared to those with the Arg/Arg genotype. In conclusion, this study provides epidemiologic evidence of a reduced bladder cancer risk associated with the SULT1A1 His(213) polymorphism. Further studies are warranted to elucidate the function of this SULT1A1 polymorphism with regard to organ specificity, gene-environment interactions, and the gender-related difference we observed.

Amino Acid Substitution↗
PubMed2003

XRCC3 genetic polymorphism, smoking, and lung carcinoma risk in minority populations.

BACKGROUND: The XRCC3 protein participates in DNA double-strand breaks and recombinational repair. A single C-to-T nucleotide change at codon 241 (Thr241Met) has been identified in the XRCC3 gene. Using a hospital-based case-control approach, the authors studied the XRCC3 polymorphism as a possible genetic risk factor for lung carcinoma in African Americans and Mexican Americans. METHODS: A total of 112 patients with lung carcinoma were frequency matched with 190 control participants on the basis of age, gender, and ethnicity. Polymerase chain reaction-restriction fragment length polymorphism molecular analysis was used successfully to identify the XRCC3 polymorphism in peripheral blood lymphocytes. RESULTS: No significant association between the XRCC3 variant allele polymorphism (odds ratio [OR], 1.25; 95% confidence interval [95% CI], 0.72-2.15) and lung carcinoma risk was noted. However, a significantly increased risk for lung carcinoma (OR, 5.20; 95% CI, 1.59-17.03) was evident in heavy smokers with the variant T-allele genotypes. Furthermore, a joint effect of the T-allele and heavy smoking was observed (OR, 37.31; 95% CI, 11.43-121.72). CONCLUSIONS: The XRCC3 polymorphism appeared to be associated with increased risk of lung carcinoma in certain subgroups. It is plausible that the association is very heavily dependent on the degree of smoking. Further studies with larger sample sizes will be necessary to confirm these findings.

Adult↗
PubMed2003

Telomere dysfunction: a potential cancer predisposition factor.

BACKGROUND: Genetic instability associated with telomere dysfunction (i.e., short telomeres) is an early event in tumorigenesis. We investigated the association between telomere length and cancer risk in four ongoing case-control studies. METHODS: All studies had equal numbers of case patients and matched control subjects (92 for head and neck cancer, 135 for bladder cancer, 54 for lung cancer, and 32 for renal cell carcinoma). Telomere length was measured in peripheral blood lymphocytes from study participants. Genetic instability was assessed with the comet assay. Patient and disease characteristics were collected and analyzed for associations with risk for these cancers. All statistical tests were two-sided. RESULTS: Telomeres were statistically significantly shorter in patients with head and neck cancer (6.5 kilobases [kb]) than in control subjects (7.4 kb) (difference = 0.9 kb, 95% confidence interval [CI] = 0.5 to 1.2 kb; P<.001). Nine percent of patients with head and neck cancer were in the longest quartile of telomere length, whereas 59% were in the shortest quartile. Similar patterns were observed for lung, renal cell, and bladder cancer. When subjects were categorized into telomere length quartiles defined by the distribution in control subjects, the following inverse relationship between telomere length and cancer risk was observed: adjusted odds ratios [ORs] for decreasing quartiles = 0.84 (95% CI = 0.36 to 1.97), 1.77 (95% CI = 0.72 to 4.36), and 5.11 (95% CI = 1.90 to 13.77). In stratified analysis, we found a suggestive greater-than-additive interaction between smoking status and telomere length: for ever smokers with short telomeres, OR = 25.05 (95% CI = 6.91 to 90.73); for never smokers with short telomeres, OR = 6.18 (95% CI = 1.72 to 22.13); and for ever smokers with long telomeres, OR = 6.49 (95% CI = 1.54 to 27.38). Telomere length was statistically significantly and inversely associated with baseline and mutagen-induced genetic instability. CONCLUSION: Short telomeres appear to be associated with increased risks for human bladder, head and neck, lung, and renal cell cancers.

Adult↗
PubMed2003

Serum levels of insulin-like growth factor I and risk of squamous intraepithelial lesions of the cervix.

Squamous intraepithelial lesions (SILs) are areas of precancerous growth in the cervix that can be indicative of future cervical cancer. Insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) have been implicated in cancer development. Recent studies have demonstrated that elevated plasma IGF-I levels are associated with increased risk of prostate, lung, colon, and breast cancers. In this case-control study, we analyzed the relationship between serum levels of IGF-I and IGFBP-3, and SILs of the cervix. The case patients were comprised of 267 women treated at The University of Texas M. D. Anderson Cancer Center Colposcopy Clinic in Houston, Texas for abnormal Pap smears. The clinic serves minority and economically disadvantaged women referred from the County Health Department clinics of Harris County, Texas. The control subjects were 238 healthy women receiving family planning and screening services at two Harris County Health Department clinics. Case patients with either high-grade or low-grade SILs had significantly higher serum levels of IGF-I, IGFBP-3, and molar ratios of IGF-I:IGFBP-3 than the control subjects did. IGF-I levels in the highest quartile were associated with significantly higher risk of SILs compared with the lowest quartile, independent of IGFBP-3 levels. The odds ratio for the fourth quartile of IGF-I level, relative to the first quartile, was 8.54 (95% confidence interval, 4.15-17.60; P < 0.0001) after adjustment for age, ethnicity, smoking status, and IGFBP-3 level. There was a dose-response relationship between risk of SILs and the level of IGF-I: as the level of IGF-I increased, so did the risk of SILs. In addition, the serum level of IGFBP-3 was significantly higher in case patients than in control subjects. However, after adjustment for IGF-I, no relationship was evident between IGFBP-3 level and risk of SILs. Serum levels of IGF-I may be a useful biomarker for assessing risk of SIL development.

Adult↗
PubMed2003

From genotype to phenotype: correlating XRCC1 polymorphisms with mutagen sensitivity.

This study correlated the extent of induced in vitro chromosomal damage, assessed by the mutagen sensitivity assay, with genotypes of the X-ray repair cross complementing group 1 (XRCC1) gene, which encodes for a base excision repair protein. There are two common polymorphisms that cause amino acid substitutions in XRCC1, one at codon 194 in exon 6 and another at codon 399 in exon 10. We genotyped these two polymorphisms in 524 healthy subjects and performed mutagen sensitivity assays using both bleomycin and benzo[a]pyrene-diol-epoxide (BPDE) as challenge mutagens. Our results showed that individuals with the wildtype exon 6 Arg/Arg exhibited significantly higher values of chromosomal breaks per cell (b/c) than those with one or two variant Trp alleles (P=0.005 for bleomycin and P=0.05 for BPDE). For the exon 10 polymorphism, subjects who were Gln/Gln homozygotes had higher b/c than did those with other genotypes, with evidence of a gene dosage effect. When we combined the two polymorphic sites and used the exon 6 Arg/Trp and Trp/Trp and exon 10 Arg/Arg genotypes as the reference category, these differences were enhanced for bleomycin sensitivity (P for trend = 0.032), but not for BPDE sensitivity (P for trend = 0.821). These data are biologically plausible since codon 399 is located within the BRCA1 C-terminus functional domain and codon 194 is in the linker region of the XRCC1 N-terminal functional domain. To our knowledge, this is the largest study conducted evaluating the functional relevance of these polymorphisms.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2003

An association between NQO1 genetic polymorphism and risk of bladder cancer.

NAD(P)H:quinone oxidoreductase (NQO1) is a detoxification enzyme that plays a critical role in protecting cells against chemically induced oxidative stress, cytotoxicity, mutagenicity, and carcinogenicity. NQO1 protects cells from oxidative damage by preventing the generation of reactive oxygen species and reducing certain environmental carcinogens, such as nitroaromatic compounds, heterocyclic amines, and possible cigarette smoke condensate. A C-->T single nucleotide polymorphism in exon 6 was shown to reduce NQO1 enzyme activity, which may diminish the protection provided by NQO1. Therefore, we hypothesized that people with the variant allele genotypes of NQO1 are at higher risk for bladder cancer. In an ongoing case-control study, the NQO1 genotypes were successfully identified by polymerase chain reaction restriction fragment length polymorphism in 265 bladder cancer patients and 261 control subjects matched for age, sex, and ethnicity. The frequency of the variant NQO1 allele was 18% for controls and 21% for cases. The variant allele genotypes of NQO1 were associated with a higher risk of bladder cancer in Caucasians (odds ratio (OR)=1.51; 95% confidence interval (CI)=1.01-2.25). Further analysis in Caucasians showed an elevated bladder cancer risk in men (OR=1.75; 95% CI=1.08-2.85) but not in women (OR=1.16; 95% CI=0.57-2.37). In addition, the variant allele genotypes were associated with higher bladder cancer risk in ever smokers (OR=1.78; 95% CI=1.06-3.00), but not in never smokers (OR=1.19; 95% CI=0.65-2.20). These results suggest that the NQO1 genetic polymorphism modulates bladder cancer risk, especially in men and ever smokers.

Aged↗
PubMed2003

Genetic instability in bladder cancer assessed by the comet assay.

BACKGROUND: Latent genetic instability has been associated with an increased risk for several cancers. We used the comet assay (single-cell gel electrophoresis) to assess whether genetic instability, as reflected by susceptibility to DNA damage, was associated with the risk of bladder cancer in a case-control study. METHODS: We used the comet assay to measure baseline and benzo[a]pyrene diol epoxide (BPDE)- and gamma-radiation-induced DNA damage in individual peripheral blood lymphocytes from 114 incident case patients with bladder cancer and 145 matched healthy control subjects. All subjects provided personal information, including smoking history. DNA damage was visualized with the comet assay and quantified by the Olive tail moment parameter, a relative measure. Multivariable analysis was used to assess relative risks for bladder cancer associated with DNA damage. All statistical tests were two-sided. RESULTS: Baseline levels of DNA damage were statistically significantly higher in case patients (tail moment = 1.40) than in control subjects (tail moment = 1.21) (difference = 0.19, 95% confidence interval [CI] = 0.04 to 0.32; P =.015), as were gamma-radiation-induced (tail moment = 4.76 versus 4.22; difference = 0.54, 95% CI = 0.11 to 0.96; P =.013) and BPDE-induced (tail moment = 4.06 versus 3.45; difference = 0.61, 95% CI = 0.23 to 0.99; P =.002) DNA damage. When data were dichotomized at the median value for DNA damage in control subjects and adjusted for age, sex, ethnicity, and smoking status, an increased estimated relative risk of bladder cancer was statistically significantly associated with DNA damage at baseline (odds ratio [OR] = 1.84, 95% CI = 1.07 to 3.15) and after gamma-radiation (OR = 1.81, 95% CI = 1.04 to 3.14) but not after BPDE treatment (OR = 1.69, 95% CI = 0.98 to 2.93). CONCLUSION: Latent genetic instability as measured by the comet assay is associated with an increased estimated relative risk of bladder cancer.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2003

Death receptor 4 and bladder cancer risk.

Tumor necrosis factor-related apoptosis-inducing ligand stimulates the extrinsic apoptoticpathway by binding to death receptors 4 (DR4) and 5 (DR5). In DR4 exon 4, a C-->G polymorphism at amino acid 626 located immediately 3' to one of the main receptor ligand interface regions, results in a threonine-->arginine change. We found that the DR4 exon 4 G/G genotype was associated with an overall decreased risk of bladder cancer in Caucasians [odds ratio (OR) = 0.58; 95% confidence interval (CI), 0.38-0.88]. This protective effect was more apparent in younger individuals (OR = 0.42; 95% CI, 0.20-0.87) than in older individuals (OR = 0.60; 95% CI, 0.35-1.02) and in women (OR = 0.45; 95% CI, 0.20-0.99) than in men (OR = 0.60; 95% CI, 0.36-0.99). Moreover, the protective effect was greater for light smokers (OR = 0.19; 95% CI, 0.06-0.59) compared with heavy smokers (OR = 0.83; 95% CI, 0.41-1.69). These data provide the first large-scale molecular epidemiological evidence that the DR4 polymorphism is associated with environmental exposure and bladder cancer risk, possibly through modulating the capacity of the receptor ligand complex to engage the apoptotic pathway.

Alleles↗
PubMed2003

Association between glutathione S-transferase p1 polymorphisms and lung cancer risk in Caucasians: a case-control study.

Glutathione transferases (GSTs), a multiple gene family of phase II enzymes, catalyze detoxifying endogenous reactions with glutathione and protect cellular macromolecules from damage caused by cytotoxic and carcinogenic agents. Glutathione S-transferase p1 (GSTP1), the most abundant GST isoform in the lung, metabolizes numerous carcinogenic compounds including benzo[a]pyrene, a tobacco carcinogen. Previous studies suggest that genetic polymorphisms of GSTP1 exon 5 (Ile105Val) and exon 6 (Ala114Val) have functional effects on the GST gene product resulting in reduced enzyme activity. Individuals with reduced GST enzymatic activity may be at a greater risk for cancer due to decreased detoxification of carcinogenic and mutagenic compounds. Utilizing a hospital-based case-control study, we investigated the association between GSTP1 polymorphisms at exons 5 and 6 with lung cancer risk. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was used to successfully genotype the GSTP1 exons 5 and 6 polymorphism in 582 Caucasian lung cancer cases and 600 frequency matched Caucasian controls. There was no association between the exon 5 variant genotypes (A/G+G/G) and overall lung cancer risk (OR=1.09; 95% CI 0.82-1.45) nor when stratified by age, gender, and smoking status. However, the exon 6 variant genotypes (C/T+T/T) were associated with a statistically significant elevated lung cancer risk (OR=1.40; 95% CI 1.06-1.92). Additionally, there was an increase in lung cancer risk for the exon 6 variant genotypes in younger individuals (<62 years) (OR=1.63; 95% C.I. 1.07-2.49) but no effect in older individuals (OR=1.14; 95% CI 0.72-1.81). A statistically significant increased risk of lung cancer was also observed for the exon 6 variant genotypes among men (OR=2.17; 95% CI 1.41-3.33), but not among women (OR=0.80; 95% CI 0.51-1.28). Among ever smokers, the exon 6 variant genotypes were associated with an elevated lung cancer risk (OR=1.58; 95% CI 1.14-2.19), which was not evident for never smokers (OR=0.53; 95% CI 0.21-1.33). These data demonstrate that the GSTP1 exon 6 polymorphism, but not the exon 5 polymorphism, is associated with lung cancer risk that is especially evident in men, younger individuals, and ever smokers.

Case-Control Studies↗
PubMed2003

XPA polymorphism associated with reduced lung cancer risk and a modulating effect on nucleotide excision repair capacity.

XPA, a DNA binding protein in the nucleotide excision repair (NER) pathway, modulates damage recognition. Recently, a common single-nucleotide polymorphism (A --> G) of unknown function was identified in the 5' non-coding region of the XPA gene. Because a deficiency in NER is associated with an increased risk of lung cancer, we evaluated the role of this polymorphism in 695 lung cancer case patients and 695 age-, sex-, ethnicity- and smoking-matched control subjects. We also studied the effect of this polymorphism on NER capacity in a subset sample for whom the host cell reactivation data were available. The presence of one or two copies of the G allele was associated with a reduced lung cancer risk for Caucasians [adjusted odds ratio (ORadj) = 0.69 [95% confidence interval (CI) = 0.53-0.90]], Mexican-Americans [ORadj = 0.32 (95% CI = 0.12-0.83)] and African-Americans [ORadj = 0.45 (95% CI = 0.16-1.22)]. In Caucasians, ever smokers with one or more copies of the G allele were observed to have a significantly reduced risk of lung cancer. Control subjects with one or two copies of the G allele demonstrated more efficient DRC than did those with the homozygous A allele. Our data suggest that the XPA 5' non-coding region polymorphism modulates NER capacity and is associated with decreased lung cancer risk, especially in the presence of exposure to tobacco carcinogens.

Base Sequence↗
PubMed2003

Plasma levels of insulin-like growth factor-1 and binding protein-3, and their association with bladder cancer risk.

PURPOSE: Because insulin-like growth factors (IGFs) and their binding proteins have been implicated in the development of prostate, breast, colon and lung cancer, we examined the role of IGF-1 and IGF binding protein-3 levels in bladder cancer risk. MATERIALS AND METHODS: We used an enzyme-linked immunosorbent assay to compare plasma levels of IGF-1 and IGF binding protein-3 in 154 patients with bladder cancer and 154 controls from an ongoing case-control study. RESULTS: Mean IGF-1 was significantly higher in cases than in controls (175.8 versus 153.2 ng./ml., p <0.01). Mean IGF binding protein-3 was significantly lower in cases than in controls (2,632.9 versus 3,056.6 ng./ml., p <0.01). The highest quartile plasma levels of IGF-1 were associated with an increased risk of bladder cancer (OR 3.10, 95% CI 1.43 to 6.70) and the highest quartile plasma levels of IGF binding protein-3 were associated with a reduced risk of bladder cancer (OR 0.38, 95% CI 0.19 to 0.78). The effects were more striking when IGF-1 and IGF binding protein-3 levels were analyzed together. In addition, a higher molar ratio of IGF-1-to-IGF binding protein-3 was associated with an increased risk of bladder cancer (OR 4.30, 95% CI 1.99 to 9.28). Dose-response relationships were evident when subjects were categorized into quartiles by the values of IGF-1, IGF binding protein-3 and the molar ratio in controls. CONCLUSIONS: To our knowledge this is the first study to suggest that patients with bladder cancer have higher plasma levels of IGF-1 and lower levels of IGF binding protein-3 than controls. Thus, measuring plasma IGF-1 and IGF binding protein-3 may be useful for assessing bladder cancer risk.

Case-Control Studies↗
PubMed2003

Genetic susceptibility for lung cancer: interactions with gender and smoking history and impact on early detection policies.

OBJECTIVES: To identify a subgroup of former, current and never smokers (males and females) at high risk for developing lung cancer, based on their genetic susceptibility profiles, to estimate their lifetime probabilities of the disease, and to assess the potential mortality reduction that could be achieved by screening the high-risk group. METHODS: Case-control data (764 cases and 677 matched controls), on two assays of DNA damage and repair (mutagen susceptibility and DNA repair capacity, DRC) in different smoking categories were used to obtain estimates of susceptibility using the formula of total probability. The estimates were inserted into a model of lung cancer natural history and detection by screening to assess mortality reduction due to screening of high-risk individuals. RESULTS: The high-risk group was defined as that 12.5% of the population who were above the third quartile for bleomycin sensitivity and below the median for DRC. High-risk male current, former, and never smokers had lifetime probabilities for developing lung cancer of 38, 21, and 5%, respectively. Females had lower probabilities to develop lung cancer: 15, 8, and 1.5% for high-risk current, former, and never smokers, respectively. Screening of high-risk smokers (12.5% of all smokers) reduced overall mortality by 7% compared to 30% reduction if all smokers were screened. Analogous results were obtained for former and never smokers. CONCLUSIONS: Genetic susceptibility constitutes an important factor in the selection of a high-risk group for early lung cancer detection.

Age of Onset↗
PubMed2003

Myeloperoxidase promoter region polymorphism and lung cancer risk.

Historically, myeloperoxidase activity and subsequent production of hypochlorous acid has been associated with the killing of host-invading microorganisms (bacteria, viruses, and fungi). Currently, there is a wealth of evidence that the MPO polymorphism and enzyme activity is associated with a wide range of pathological and biological processes, including lung cancer carcinogenesis. Although the molecular epidemiology reports reviewed in this chapter are not in complete agreement on all aspects of their findings, it is evident that the MPO polymorphism contributes to the modulation of overall lung cancer risk. Four of the five molecular epidemiologic studies reviewed in this chapter utilized similar case-control study designs with quite different sources of populations. These studies all demonstrate that the MPO variant genotype modulates overall lung cancer risk. However, these studies are not in agreement regarding age and gender effects, and gene-environmental interactions. The nested case control study designed utilized by Misra et al. (35) is a valid and sound approach, but their results found no evidence of an association. Certainly, heterogeneity in study populations can contribute to the variability between these studies. Additionally, epidemiologic issues such as case-control matching and sources of control populations may contribute to the conflicting findings. Thus, the publication of inconsistent or null studies as well as other positive findings is certainly encouraged to elucidate the range of effects associated with the MPO polymorphism and lung cancer risk.

Genotype↗