The National Lung Screening Trial (NLST) used risk factors for lung cancer (e.g., ≥30 pack-years of smoking and <15 years since quitting) as selection criteria for lung-cancer screening. Use of an accurate model that incorporates additional risk factors to select persons for screening may identify more persons who have lung cancer or in whom lung cancer will develop.
We modified the 2011 lung-cancer risk-prediction model from our Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial to ensure applicability to NLST data; risk was the probability of a diagnosis of lung cancer during the 6-year study period. We developed and validated the model (PLCOM2012) with data from the 80,375 persons in the PLCO control and intervention groups who had ever smoked. Discrimination (area under the receiver-operating-characteristic curve [AUC]) and calibration were assessed. In the validation data set, 14,144 of 37,332 persons (37.9%) met NLST criteria. For comparison, 14,144 highest-risk persons were considered positive (eligible for screening) according to PLCOM2012 criteria. We compared the accuracy of PLCOM2012 criteria with NLST criteria to detect lung cancer. Cox models were used to evaluate whether the reduction in mortality among 53,202 persons undergoing low-dose computed tomographic screening in the NLST differed according to risk.
The AUC was 0.803 in the development data set and 0.797 in the validation data set. As compared with NLST criteria, PLCOM2012 criteria had improved sensitivity (83.0% vs. 71.1%, P<0.001) and positive predictive value (4.0% vs. 3.4%, P = 0.01), without loss of specificity (62.9% and. 62.7%, respectively; P = 0.54); 41.3% fewer lung cancers were missed. The NLST screening effect did not vary according to PLCOM2012 risk (P = 0.61 for interaction).
The use of the PLCOM2012 model was more sensitive than the NLST criteria for lung-cancer detection.
Osteosarcoma is the most common primary bone malignancy of adolescents and young adults. In order to better understand the genetic etiology of osteosarcoma, we performed a multi-stage genome-wide association study (GWAS) consisting of 941 cases and 3,291 cancer-free adult controls of European ancestry. Two loci achieved genome-wide significance: rs1906953 at 6p21.3, in the glutamate receptor metabotropic 4 [GRM4] gene (P = 8.1 ×10-9), and rs7591996 and rs10208273 in a gene desert on 2p25.2 (P = 1.0 ×10-8 and 2.9 ×10-7). These two susceptibility loci warrant further exploration to uncover the biological mechanisms underlying susceptibility to osteosarcoma.
In the National Lung Screening Trial (NLST), screening with low-dose computed tomography (CT) resulted in a 20% reduction in lung-cancer mortality among participants between the ages of 55 and 74 years with a minimum of 30 pack-years of smoking and no more than 15 years since quitting. It is not known whether the benefits and potential harms of such screening vary according to lung-cancer risk.
We assessed the variation in efficacy, the number of false positive results, and the number of lung-cancer deaths prevented among 26,604 participants in the NLST who underwent low-dose CT screening, as compared with the 26,554 participants who underwent chest radiography, according to the quintile of 5-year risk of lung-cancer death (ranging from 0.15 to 0.55% in the lowest-risk group [quintile 1] to more than 2.00% in the highest-risk group [quintile 5]).
The number of lung-cancer deaths per 10,000 person-years that were prevented in the CT-screening group, as compared with the radiography group, increased according to risk quintile (0.2 in quintile 1, 3.5 in quintile 2, 5.1 in quintile 3, 11.0 in quintile 4, and 12.0 in quintile 5; P = 0.01 for trend). Across risk quintiles, there were significant decreasing trends in the number of participants with false positive results per screening-prevented lung-cancer death (1648 in quintile 1, 181 in quintile 2, 147 in quintile 3, 64 in quintile 4, and 65 in quintile 5). The 60% of participants at highest risk for lung-cancer death (quintiles 3 through 5) accounted for 88% of the screening-prevented lung-cancer deaths and for 64% of participants with false positive results. The 20% of participants at lowest risk (quintile 1) accounted for only 1% of prevented lung-cancer deaths.
Screening with low-dose CT prevented the greatest number of deaths from lung cancer among participants who were at highest risk and prevented very few deaths among those at lowest risk. These findings provide empirical support for risk-based targeting of smokers for such screening. (Funded by the National Cancer Institute.)
Smoking has been hypothesized to decrease biosynthesis of parent estrogens (estradiol and estrone) and increase their metabolism by 2-hydroxylation. However, comprehensive studies of smoking and estrogen metabolism by 2-, 4-, or 16-hydroxylation are sparse.
Fifteen urinary estrogens and estrogen metabolites (jointly called EM) were measured by liquid chromatography-tandem mass spectrometry in luteal phase urines collected during 1996–99 from 603 premenopausal women in Nurses’ Health Study II (35 current, 140 former, 428 never smokers). We calculated geometric means and percent differences of individual EM (pmol/mg creatinine), metabolic pathway groups, and pathway ratios, by smoking status and cigarettes per day (CPD).
Total EM and parent estrogens were nonsignificantly lower in current compared to never smokers, with estradiol significant (pmultivariate=0.02). We observed nonsignificantly lower 16-pathway EM (p=0.08) and higher 4-pathway EM (p=0.25) and similar 2-pathway EM in current vs. never smokers. EM measures among former smokers were similar to never smokers. Increasing CPD was significantly associated with lower 16-pathway EM (p-trend=0.04) and higher 4-pathway EM (p-trend=0.05). Increasing CPD was significantly positively associated with the ratios of 2- and 4-pathway to parent estrogens (p-trend=0.01 and 0.002), 2- and 4-pathway to 16-pathway (p-trend=0.02 and 0.003), and catechols to methylated catechols (p-trend=0.02).
As hypothesized, we observed lower urinary levels of total EM and parent estrogens in active smokers. Our results also suggest smoking is associated with altered estrogen metabolism, specifically increased 2- and 4-hydroxylation, decreased 16-hydroxylation, and decreased catechol methylation.
Our study suggests how smoking might influence estrogen-related cancers and conditions.
Estradiol; estrogen metabolism; smoking; urine
A recent genome-wide association study (GWAS) of subjects from Japan and South Korea reported a novel association between the TP63 locus on chromosome 3q28 and risk of lung adenocarcinoma (p = 7.3 × 10−12); however, this association did not achieve genome-wide significance (p < 10−7) among never-smoking males or females. To determine if this association with lung cancer risk is independent of tobacco use, we genotyped the TP63 SNPs reported by the previous GWAS (rs10937405 and rs4488809) in 3,467 never-smoking female lung cancer cases and 3,787 never-smoking female controls from 10 studies conducted in Taiwan, Mainland China, South Korea, and Singapore. Genetic variation in rs10937405 was associated with risk of lung adenocarcinoma [n = 2,529 cases; p = 7.1 × 10−8; allelic risk = 0.80, 95% confidence interval (CI) = 0.74–0.87]. There was also evidence of association with squamous cell carcinoma of the lung (n = 302 cases; p = 0.037; allelic risk = 0.82, 95% CI = 0.67–0.99). Our findings provide strong evidence that genetic variation in TP63 is associated with the risk of lung adenocarcinoma among Asian females in the absence of tobacco smoking.
We outline an integrative approach to extend the boundaries of molecular cancer epidemiology by integrating modern and rapidly evolving “omics” technologies into state-of-the-art molecular epidemiology. In this way, one can comprehensively explore the mechanistic underpinnings of epidemiologic observations into cancer risk and outcome. We highlight the exciting opportunities to collaborate across large observational studies and to forge new interdisciplinary collaborative ventures.
multidisciplinary epidemiologic research; integrating new technologies
Genome-wide association studies (GWAS) have identified 36 loci associated with body mass index (BMI), predominantly in populations of European ancestry. We conducted a meta-analysis to examine the association of >3.2 million SNPs with BMI in 39,144 men and women of African ancestry, and followed up the most significant associations in an additional 32,268 individuals of African ancestry. We identified one novel locus at 5q33 (GALNT10, rs7708584, p=3.4×10−11) and another at 7p15 when combined with data from the Giant consortium (MIR148A/NFE2L3, rs10261878, p=1.2×10−10). We also found suggestive evidence of an association at a third locus at 6q16 in the African ancestry sample (KLHL32, rs974417, p=6.9×10−8). Thirty-two of the 36 previously established BMI variants displayed directionally consistent effect estimates in our GWAS (binomial p=9.7×10−7), of which five reached genome-wide significance. These findings provide strong support for shared BMI loci across populations as well as for the utility of studying ancestrally diverse populations.
Epidemiologic studies have reported that frequent consumption of quercetin-rich foods is inversely associated with lung cancer incidence. A quercetin-rich diet might modulate microRNA (miR) expression; however, this mechanism has not been fully examined.
miR expression data were measured by a custom-made array in formalin-fixed paraffin-embedded tissue samples from 264 lung cancer cases (144 adenocarcinomas and 120 squamous cell carcinomas). Intake of quercetin-rich foods was derived from a food-frequency questionnaire. In individual-miR-based analyses, we compared the expression of miRs (n=198) between lung cancer cases consuming high-versus-low quercetin-rich food intake using multivariate ANOVA tests. In family-miR-based analyses, we used Functional Class Scoring (FCS) to assess differential effect on biologically functional miRs families. We accounted for multiple testing using 10,000 global permutations (significance at p-valueglobal <0.10). All multivariate analyses were conducted separately by histology and by smoking status (former and current smokers).
Family-based analyses showed that a quercetin-rich diet differentiated miR expression profiles of the tumor suppressor let-7 family among adenocarcinomas (p-valueFCS<0.001). Other significantly differentiated miR families included carcinogenesis-related miR-146, miR-26, and miR-17 (p-valuesFCS<0.05). In individual-based analyses, we found that among former and current smokers with adenocarcinoma, 33 miRs were observed to be differentiated between highest-and-lowest quercetin-rich food consumers (23 expected by chance; p-valueglobal = 0.047).
We observed differential expression of key biologically functional miRNAs between high-versus-low consumers of quercetin-rich foods in adenocarcinoma cases.
Our findings provide preliminary evidence on the mechanism underlying quercetin-related lung carcinogenesis.
Additive risk models are necessary for understanding the joint effects of exposures on individual and population disease risk. Yet technical challenges have limited the consideration of additive risk models in case–control studies.
Using a flexible risk regression model that allows additive and multiplicative components to estimate absolute risks and risk differences, we report a new analysis of data from the population-based case–control Environment And Genetics in Lung cancer Etiology study, conducted in Northern Italy between 2002–2005. The analysis provides estimates of the gender-specific absolute risk (cumulative risk) for non-smoking- and smoking-associated lung cancer, adjusted for demographic, occupational, and smoking history variables.
In the multiple-variable lexpit regression, the adjusted 3-year absolute risk of lung cancer in never smokers was 4.6 per 100,000 persons higher in women than men. However, the absolute increase in 3-year risk of lung cancer for every 10 additional pack-years smoked was less for women than men, 13.6 versus 52.9 per 100,000 persons.
In a Northern Italian population, the absolute risk of lung cancer among never smokers is higher in women than men but among smokers is lower in women than men. Lexpit regression is a novel approach to additive-multiplicative risk modeling that can contribute to clearer interpretation of population-based case–control studies.
Additive risk; Absolute risk; Case–control study; EAGLE; Lung cancer; Risk assessment; Sex factors; Smoking
Pulmonary inflammation may contribute to lung cancer etiology. We conducted a broad evaluation of the association of single nucleotide polymorphisms (SNPs) in innate immunity and inflammation pathways with lung cancer risk, and conducted comparisons with a lung cancer genome wide association study (GWAS).
We included 378 lung cancer cases and 450 controls from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. An Illumina GoldenGate oligonucleotide pool assay was used to genotype 1,429 SNPs. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for each SNP, and p-values for trend were calculated. For statistically significant SNPs (p-trend<0.05), we replicated our results with genotyped or imputed SNPs in the GWAS, and adjusted p-values for multiple testing.
In our PLCO analysis, we observed a significant association between 81 SNPs located in 44 genes and lung cancer (p-trend<0.05). Of these 81 SNPS, there was evidence for confirmation in the GWAS for 10 SNPs. However, after adjusting for multiple comparisons, the only SNP that remained significantly associated with lung cancer in the replication phase was rs4648127 (NFKB1; multiple testing adjusted p-trend=0.02). The CT/TT genotype of NFKB1 was associated with reduced odds of lung cancer in the PLCO study (OR=0.56; 95% CI 0.37–0.86) and the GWAS (OR=0.79; 95% CI 0.69–0.90).
We found a significant association between a variant in the NFKB1 gene and lung cancer risk. Our findings add to evidence implicating inflammation and immunity in lung cancer etiology.
lung cancer; genetics; inflammation; immunity; epidemiology
Large fractions of the human population do not express GSTM1 and GSTT1 (GSTM1/T1) enzymes because of deletions in these genes. These variations affect xenobiotic metabolism and have been evaluated in relation to lung cancer risk, mostly based on null/present gene models. We measured GSTM1/T1 heterozygous deletions, not tested in genome-wide association studies, in 2120 controls and 2100 cases from the Environment And Genetics in Lung cancer Etiology (EAGLE) study. We evaluated their effect on mRNA expression on lung tissue and peripheral blood samples and their association with lung cancer risk overall and by histology types. We tested the null/present, dominant and additive models using logistic regression. Cigarette smoking and gender were studied as possible modifiers. Gene expression from blood and lung tissue cells was strongly down-regulated in subjects carrying GSTM1/T1 deletions by both trend and dominant models (p<0.001). In contrast to the null/present model, analyses distinguishing subjects with 0, 1 or 2 GSTM1/T1 deletions revealed several associations. There was a decreased lung cancer risk in never-smokers (OR=0.44;95%CI=0.23–0.82; p=0.01) and women (OR=0.50;95%CI=0.28–0.90; p=0.02) carrying 1 or 2 GSTM1 deletions. Analogously, male smokers had an increased risk (OR=1.13;95%CI=1.0–1.28; p=0.05) and women a decreased risk (OR=0.78;95%CI=0.63–0.97; p=0.02) for increasing GSTT1 deletions. The corresponding gene-smoking and gene-gender interactions were significant (p<0.05). Our results suggest that decreased activity of GSTM1/T1 enzymes elevates lung cancer risk in male smokers, likely due to impaired carcinogens’ detoxification. A protective effect of the same mutations may be operative in never-smokers and women, possibly because of reduced activity of other genotoxic chemicals.
GST; copy numbers; gene expression; lung cancer; smoking and gender differences
Lung cancer is mainly caused by smoking, but the quantitative relations between smoking and histologic subtypes of lung cancer remain inconclusive. Using one of the largest lung cancer datasets ever assembled, we explored the impact of smoking on risks of the major cell types of lung cancer. This pooled analysis included 13,169 cases and 16,010 controls from Europe and Canada. Studies with population controls comprised 66.5% of the subjects. Adenocarcinoma (AdCa) was the most prevalent subtype in never smokers and in women. Squamous cell carcinoma (SqCC) predominated in male smokers. Age-adjusted odds ratios (ORs) were estimated with logistic regression. ORs were elevated for all metrics of exposure to cigarette smoke and were higher for SqCC and small cell lung cancer (SCLC) than for AdCa. Current male smokers with an average daily dose of >30 cigarettes had ORs of 103.5 (95% CI 74.8-143.2) for SqCC, 111.3 (95% CI 69.8-177.5) for SCLC, and 21.9 (95% CI 16.6-29.0) for AdCa. In women, the corresponding ORs were 62.7 (95% CI 31.5-124.6), 108.6 (95% CI 50.7-232.8), and 16.8 (95% CI 9.2-30.6), respectively. Whereas ORs started to decline soon after quitting, they did not fully return to the baseline risk of never smokers even 35 years after cessation. The major result that smoking exerted a steeper risk gradient on SqCC and SCLC than on AdCa is in line with previous population data and biological understanding of lung cancer development.
cigarette smoking; lung cancer; relative risk characterization; tobacco smoke; stem cells
Owing to their role in controlling the efflux of toxic compounds, transporters are central players in the process of detoxification and elimination of xenobiotics, which in turn is related to cancer risk. Among these transporters, ATP-binding cassette B1/multidrug resistance 1 (ABCB1/MDR1), ABCC2/multidrug resistance protein 2 (MRP2), and ABCG2/breast cancer resistance protein (BCRP) affect susceptibility to many hematopoietic malignancies. The maintenance of regulated expression of these transporters is governed through the activation of intracellular “xenosensors” like the nuclear receptor 1I2/pregnane X receptor (NR1I2/PXR). SNPs in genes encoding these regulators have also been implicated in the risk of several cancers. Using a tagging approach, we tested the hypothesis that common polymorphisms in the transporter genes ABCB1, ABCC2, ABCG2, and the regulator gene NR1I2 could be implicated in lymphoma risk. We selected 68 SNPs in the 4 genes, and we genotyped them in 1,481 lymphoma cases and 1,491 controls of the European cases-control study (EpiLymph) using the Illumina™ GoldenGate assay technology.Carriers of the SNP rs6857600 minor allele in ABCG2, was associated with a decrease in risk of B-cell lymphoma (B-NHL) overall (p<0.001). Furthermore, a decreased risk of chronic lymphocytic leukemia (CLL) was associated with the ABCG2 rs2231142 variant (p=0.0004), which could be replicated in an independent population. These results suggest a role for this gene in B-NHL susceptibility, especially for CLL.
Lymphoma; multidrug resistance 1 (MDR1); multidrug resistance protein 2 (MRP2); breast cancer resistance protein (BCRP); pregnane X receptor (PXR)
Background Exposure to occupational carcinogens is an important preventable cause of lung cancer. Most of the previous studies were in highly exposed industrial cohorts. Our aim was to quantify lung cancer burden attributable to occupational carcinogens in a general population.
Methods We applied a new job–exposure matrix (JEM) to translate lifetime work histories, collected by personal interview and coded into standard job titles, into never, low and high exposure levels for six known/suspected occupational lung carcinogens in the Environment and Genetics in Lung cancer Etiology (EAGLE) population-based case–control study, conducted in Lombardy region, Italy, in 2002–05. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in men (1537 cases and 1617 controls), by logistic regression adjusted for potential confounders, including smoking and co-exposure to JEM carcinogens. The population attributable fraction (PAF) was estimated as impact measure.
Results Men showed an increased lung cancer risk even at low exposure to asbestos (OR: 1.76; 95% CI: 1.42–2.18), crystalline silica (OR: 1.31; 95% CI: 1.00–1.71) and nickel–chromium (OR: 1.18; 95% CI: 0.90–1.53); risk increased with exposure level. For polycyclic aromatic hydrocarbons, an increased risk (OR: 1.64; 95% CI: 0.99–2.70) was found only for high exposures. The PAFs for any exposure to asbestos, silica and nickel–chromium were 18.1, 5.7 and 7.0%, respectively, equivalent to an overall PAF of 22.5% (95% CI: 14.1–30.0). This corresponds to about 1016 (95% CI: 637–1355) male lung cancer cases/year in Lombardy.
Conclusions These findings support the substantial role of selected occupational carcinogens on lung cancer burden, even at low exposures, in a general population.
lung neoplasms; case–control study; carcinogens; occupational health
The detection of tumor suppressor gene promoter methylation in sputum-derived exfoliated cells predicts early lung cancer. Here we identified genetic determinants for this epigenetic process and examined their biological effects on gene regulation. A two-stage approach involving discovery and replication was employed to assess the association between promoter hypermethylation of a 12-gene panel and common variation in 40 genes involved in carcinogen metabolism, regulation of methylation, and DNA damage response in members of the Lovelace Smokers Cohort (n=1434). Molecular validation of three identified variants was conducted using primary bronchial epithelial cells. Association of study-wide significance (P<8.2×10−5) was identified for rs1641511, rs3730859, and rs1883264 in TP53, LIG1, and BIK, respectively. These SNPs were significantly associated with altered expression of the corresponding genes in primary bronchial epithelial cells. In addition, rs3730859 in LIG1 was also moderately associated with increased risk for lung cancer among Caucasian smokers. Together, our findings suggest that genetic variation in DNA replication and apoptosis pathways impacts the propensity for gene promoter hypermethylation in the aerodigestive tract of smokers. The incorporation of genetic biomarkers for gene promoter hypermethylation with clinical and somatic markers may improve risk assessment models for lung cancer.
DNA damage response; promoter hypermethylation; single nucleotide polymorphism; sputum; smoker
No prior studies have related a tobacco-specific carcinogen to risk of lung cancer in smokers. Of the over 60 known carcinogens in cigarette smoke, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is specific to tobacco and causes lung cancer in laboratory animals. Its metabolites, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides (total NNAL), have been studied as biomarkers of exposure to NNK. We studied the relation of prospectively measured NNK biomarkers to lung cancer risk.
In a case-control study nested in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we randomly selected 100 lung cancer cases and 100 controls who smoked at baseline and analyzed their baseline serum for total NNAL, cotinine and r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene (PheT), a biomarker of polycyclic aromatic hydrocarbon exposure and metabolic activation. To examine the association of the biomarkers with all lung cancer and for histologic subtypes, we computed odds ratios (OR) for total NNAL, PheT and cotinine using logistic regression to adjust for potential confounders.
Individual associations of age, smoking duration, and total NNAL with lung cancer risk were statistically significant. After adjustment, total NNAL was the only biomarker significantly associated with risk (OR = 1.57 per unit standard deviation increase, 95% confidence interval: 1.08, 2.28). A similar statistically significant result was obtained for adenocarcinoma risk, but not for non-adenocarcinoma.
This first reporting of the effect of the prospectively measured tobacco-specific biomarker, total NNAL, on risk of lung cancer in smokers provides insight into the etiology of smoking-related lung cancer and reinforces targeting NNK for cancer prevention.
Other than male sex, family history, advanced age, and race, risk factors for chronic lymphocytic leukemia and small lymphocytic lymphoma (CLL/SLL) are unknown. Very few studies have investigated diet in relation to these leukemias, and no consistent associations are known.
Using two large prospective population-based studies, we evaluated the relationship between diet and CLL/SLL risk. Among 525,982 men and women free of cancer at enrollment, we identified 1,129 incident CLL/SLL cases during 11.2 years of follow-up.
We found no associations between total fat, saturated fat, fiber, red meat, processed meat, fruit or vegetable intake and risk of CLL/SLL. We noted a suggestive positive association between body mass index (BMI) and CLL/SLL (hazard ratio =1.30; 95% confidence interval= 0.99-1.36).
We did not find any associations between foods or nutrients and CLL/SLL.
Our large prospective study indicates that diet may not play a role in CLL/SLL development.
diet; chronic lymphocytic leukemia; body mass index; cohort study
Tobacco-induced lung cancer is characterized by a deregulated inflammatory microenvironment. Variants in multiple genes in inflammation pathways may contribute to risk of lung cancer.
We therefore conducted a three-stage comprehensive pathway analysis (discovery, replication and meta-analysis) of inflammation gene variants in ever smoking lung cancer cases and controls. A discovery set (1096 cases; 727 controls) and an independent and non-overlapping internal replication set (1154 cases; 1137 controls) were derived from an ongoing case-control study. For discovery, we used an iSelect BeadChip to interrogate a comprehensive panel of 11737 inflammation pathway SNPs and selected nominally significant (p<0.05) SNPs for internal replication.
There were 6 SNPs that achieved statistical significance (p<0.05) in the internal replication dataset with concordant risk estimates for former smokers and 5 concordant and replicated SNPs in current smokers. Replicated hits were further tested in a subsequent meta-analysis using external data derived from two published GWAS and a case-control study. Two of these variants (a BCL2L14 SNP in former smokers and a SNP in IL2RB in current smokers) were further validated. In risk score analyses, there was a 26% increase in risk with each additional adverse allele when we combined the genotyped SNP and the most significant imputed SNP in IL2RB in current smokers and a 36% similar increase in risk for former smokers associated with genotyped and imputed BCL2L14 SNPs.
Before they can be applied for risk prediction efforts, these SNPs should be subject to further external replication and more extensive fine mapping studies.
Inflammation SNPS; lung cancer; smokers
Affordable early screening in subjects with high risk of lung cancer has great potential to improve survival from this deadly disease. We measured gene expression from lung tissue and peripheral whole blood (PWB) from adenocarcinoma cases and controls to identify dysregulated lung cancer genes that could be tested in blood to improve identification of at-risk patients in the future. Genome-wide mRNA expression analysis was conducted in 153 subjects (73 adenocarcinoma cases, 80 controls) from the Environment And Genetics in Lung cancer Etiology (EAGLE) study using PWB and paired snap-frozen tumor and non-involved lung tissue samples. Analyses were conducted using unpaired t-tests, linear mixed effects and ANOVA models. The area under the receiver operating characteristic curve (AUC) was computed to assess the predictive accuracy of the identified biomarkers. We identified 50 dysregulated genes in stage I adenocarcinoma versus control PWB samples (False Discovery Rate ≤0.1, fold change ≥1.5 or ≤0.66). Among them, eight (TGFBR3, RUNX3, TRGC2, TRGV9, TARP, ACP1, VCAN, and TSTA3) differentiated paired tumor versus non-involved lung tissue samples in stage I cases, suggesting a similar pattern of lung cancer-related changes in PWB and lung tissue. These results were confirmed in two independent gene expression analyses in a blood-based case-control study (n=212) and a tumor-non tumor paired tissue study (n=54). The eight genes discriminated patients with lung cancer from healthy controls with high accuracy (AUC=0.81, 95% CI=0.74–0.87). Our finding suggests the use of gene expression from PWB for the identification of early detection markers of lung cancer in the future.
microarray gene expression; peripheral blood; lung cancer; stage I
Inflammation and pulmonary diseases, including interstitial lung diseases, are associated with increased lung cancer risk. Circulating levels of surfactant protein-D (SP-D) and Krebs von Lungren-6 (KL-6) are elevated in interstitial lung disease patients, and may be useful markers of processes contributing to lung cancer.
We conducted a nested case-control study, including 532 lung cancer cases, 582 matched controls and 150 additional controls with chest x-ray (CXR) evidence of pulmonary scarring, in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Serum SP-D and KL-6 levels were measured using enzyme immunoassay. Logistic regression was used to estimate the associations of SP-D and KL-6 with lung cancer and CXR scarring.
Cases had higher levels than controls for SP-D (median 118.7 vs. 105.4 ng/ml, p-value=0.008) and KL-6 (372.0 vs. 325.8 μg/ml, p-value=0.001). Lung cancer risk increased with SP-D (p-trend=0.0003) and KL-6 levels (p-trend=0.005). Compared to the lowest quartile, lung cancer risk was elevated among those with the highest quartiles of SP-D (odds ratio [OR]=1.87; 95% confidence interval [CI] 1.32–2.64), or KL-6 (OR=1.58; 95% CI 1.11–2.25). Among controls, participants with CXR scarring were more likely than those without scarring to have elevated levels of SP-D (quartile 4 vs. quartile 1: OR=1.67; 95% CI: 1.04–2.70; p-trend=0.05) but not of KL-6 (OR=1.04; 95% CI: 0.64–1.68; p-trend=0.99).
Circulating levels of SP-D and KL-6 are associated with subsequent lung cancer risk.
Our findings support a potential role for interstitial lung disease in lung cancer etiology or early detection, but additional research is needed.
lung cancer; inflammation; epidemiology; infections in the etiology of cancer
Recent genome-wide association studies (GWASs) have identified common genetic variants at 5p15.33, 6p21–6p22 and 15q25.1 associated with lung cancer risk. Several other genetic regions including variants of CHEK2 (22q12), TP53BP1 (15q15) and RAD52 (12p13) have been demonstrated to influence lung cancer risk in candidate- or pathway-based analyses. To identify novel risk variants for lung cancer, we performed a meta-analysis of 16 GWASs, totaling 14 900 cases and 29 485 controls of European descent. Our data provided increased support for previously identified risk loci at 5p15 (P = 7.2 × 10−16), 6p21 (P = 2.3 × 10−14) and 15q25 (P = 2.2 × 10−63). Furthermore, we demonstrated histology-specific effects for 5p15, 6p21 and 12p13 loci but not for the 15q25 region. Subgroup analysis also identified a novel disease locus for squamous cell carcinoma at 9p21 (CDKN2A/p16INK4A/p14ARF/CDKN2B/p15INK4B/ANRIL; rs1333040, P = 3.0 × 10−7) which was replicated in a series of 5415 Han Chinese (P = 0.03; combined analysis, P = 2.3 × 10−8). This large analysis provides additional evidence for the role of inherited genetic susceptibility to lung cancer and insight into biological differences in the development of the different histological types of lung cancer.
AIM: To explore the association between methylation in leukocyte DNA and colorectal cancer (CRC) risk in male smokers using the α-tocopherol, β-carotene cancer prevention study.
METHODS: About 221 incident CRC cases, and 219 controls, frequency-matched on age and smoking intensity were included. DNA methylation of 1505 CpG sites selected from 807 genes were evaluated using Illumina GoldenGate Methylation Cancer Panel I in pre-diagnostic blood leukocytes of study subjects. Tertiles of methylation level classified according to the distribution in controls for each CpG site were used to analyze the association between methylation level and CRC risk with logistic regression. The time between blood draw to cancer diagnosis (classifying cases according to latency) was incorporated in further analyses using proportional odds regression.
RESULTS: We found that methylation changes of 31 CpG sites were associated with CRC risk at P < 0.01 level. Though none of these 31 sites remained statistically significant after Bonferroni correction, the most statistically significant CpG site associated with CRC risk achieved a P value of 1.0 × 10-4. The CpG site is located in DSP gene, and the risk estimate was 1.52 (95% CI: 0.91-2.53) and 2.62 (95% CI: 1.65-4.17) for the second and third tertile comparing with the lowest tertile respectively. Taking the latency information into account strengthened some associations, suggesting that the methylation levels of corresponding sites might change over time with tumor progression.
CONCLUSION: The results suggest that the methylation level of some genes were associated with cancer susceptibility and some were related to tumor development over time. Further studies are warranted to confirm and refine our results.
DNA methylation; Colorectal cancer; Susceptibility
Although it is recognized that many common complex diseases are a result of multiple genetic and environmental risk factors, studies of gene-environment interaction remain a challenge and have had limited success to date. Given the current state-of-the-science, NIH sought input on ways to accelerate investigations of gene-environment interplay in health and disease by inviting experts from a variety of disciplines to give advice about the future direction of gene-environment interaction studies. Participants of the NIH Gene-Environment Interplay Workshop agreed that there is a need for continued emphasis on studies of the interplay between genetic and environmental factors in disease and that studies need to be designed around a multifaceted approach to reflect differences in diseases, exposure attributes, and pertinent stages of human development. The participants indicated that both targeted and agnostic approaches have strengths and weaknesses for evaluating main effects of genetic and environmental factors and their interactions. The unique perspectives represented at the workshop allowed the exploration of diverse study designs and analytical strategies, and conveyed the need for an interdisciplinary approach including data sharing, and data harmonization to fully explore gene-environment interactions. Further, participants also emphasized the continued need for high-quality measures of environmental exposures and new genomic technologies in ongoing and new studies.
gene-environment interaction; epidemiology; study design; genetics; environment