Lung cancer risk in families of nonsmoking probands: heterogeneity by age at diagnosis

A two-stage genome-wide association study identified four potential early-onset nonsmall cell lung cancer risk loci based on 26,652 participants in Chinese population

Early-onset lung cancer is rare with an increasing incidence rate. Although several genetic variants have been identified for it with candidate gene approaches, no genome-wide association study (GWAS) has been reported. In this study, a two-stage strategy was adopted: firstly we performed a GWAS to identify variants associated with early-onset nonsmall-cell lung cancer (NSCLC) risk using 2556 cases (age ≤ 50 years) and 13,327 controls by logistic regression model. To further discriminate younger cases from older ones, we took a case-case analysis for the promising variants with above early-onset cases and 10,769 cases (age > 50 years) by Cox regression model. After combining these results, we identified four early-onset NSCLC susceptibility loci at 5p15.33 (rs2853677, odds ratio [OR] = 1.48, 95% confidence interval [CI]: 1.36-1.60, Pcase-control  = 3.58 × 10-21 ; hazard ratio [HR] = 1.10, 95% CI: 1.04-1.16, Pcase-case  = 6.77 × 10-4 ), 5p15.1 (rs2055817, OR = 1.24, 95% CI: 1.15-1.35, Pcase-control  = 1.39 × 10-7 ; HR = 1.08, 95% CI: 1.02-1.14, Pcase-case  = 6.90 × 10-3 ), 6q24.2 (rs9403497, OR = 1.24, 95% CI: 1.15-1.35, Pcase-control  = 1.61 × 10-7 ; HR = 1.11, 95% CI: 1.05-1.17, Pcase-case  = 3.60 × 10-4 ) and 12q14.3 (rs4762093, OR = 1.31, 95% CI: 1.18-1.45, Pcase-control  = 1.90 × 10-7 ; HR = 1.10, 95% CI: 1.03-1.18, Pcase-case  = 7.49 × 10-3 ). Except for 5p15.33, other loci were found to be associated with NSCLC risk for the first time. All of them had stronger effects in younger patients than in older ones. These results provide a promising overview for early-onset NSCLC genetics.

Targeting lung cancer screening to individuals at greatest risk: the role of genetic factors

Lung cancer (LC) is the most common global cancer. An individual’s risk of developing LC is mediated by an array of factors, including family history of the disease. Considerable research into genetic risk factors for LC has taken place in recent years, with both low-penetrance and high-penetrance variants implicated in increasing or decreasing a person’s risk of the disease. LC is the leading cause of cancer death worldwide; poor survival is driven by late onset of non-specific symptoms, resulting in late-stage diagnoses. Evidence for the efficacy of screening in detecting cancer earlier, thereby reducing lung-cancer specific mortality, is now well established. To ensure the cost-effectiveness of a screening programme and to limit the potential harms to participants, a risk threshold for screening eligibility is required. Risk prediction models (RPMs), which provide an individual’s personal risk of LC over a particular period based on a large number of risk factors, may improve the selection of high-risk individuals for LC screening when compared with generalised eligibility criteria that only consider smoking history and age. No currently used RPM integrates genetic risk factors into its calculation of risk. This review provides an overview of the evidence for LC screening, screening related harms and the use of RPMs in screening cohort selection. It gives a synopsis of the known genetic risk factors for lung cancer and discusses the evidence for including them in RPMs, focusing in particular on the use of polygenic risk scores to increase the accuracy of targeted lung cancer screening.

Single-nucleotide polymorphism rs17548629 in RIPK1 gene may be associated with lung cancer in a young and middle-aged Han Chinese population

Background

Genetic biomarkers of lung cancer (LC) susceptibility may provide a basis for treatment and prevention. This study analyzed an association between SNPs (single nucleotide polymorphisms) in the complementary region of the 3′-UTR (3′ untranslated region) of microRNAs of the gene RIPK1 (receptor-interacting serine/threonine-protein kinase 1) and LC among an adult Han Chinese population aged younger than 60 years. Also explored the effect of regulation of the RIPK1 gene via rs17548629 and microRNA-1197 on the occurrence of LC.

Methods

RIPK1 variants (rs17548629, rs77736895) were determined in a population of 571 adults (younger than 60 years) with LC, and 609 gender- and age-matched healthy individuals. Bioinformatics methods predicted the microRNAs bound to rs17548629. Dual luciferase reporter assay was performed to confirm the presence of both rs17548629 and the predicted microRNA.

Results

A mutation (T) of rs17548629 was associated with an increased risk for LC in this population under the codominant and recessive genetic models. The risk of lung adenocarcinoma in rs17548629 mutant carriers was 1.769-fold higher than that of the wildtype. In vitro, the luciferase activity of co-transfected mutant psiCHECK2-RIPK1 and microRNA-1197 mimics was less than that of the group transfected with microRNA-1197 mimics only. Factorial analysis indicated interactions between microRNA-1197 mimics and genotypes of rs17548629.

Conclusion

A mutation (T) of rs17548629 may increase the risk of LC/lung adenocarcinoma in adult Han populations younger than 60 years. When carrying the T allele, rs17548629 may be the target of hsa-miR-1197. This mutation may affect transcriptional level of the RIPK1, thereby promoting the occurrence of LC.

Inherited lung cancer: a review

Lung cancer is the most common cancer worldwide and has high rates of mortality. The major risk factor associated with this disease is tobacco smoke, but approximately 10%-25% of all lung cancer cases occur in patients who have never smoked. Data suggest that lung cancer in never-smokers has a different molecular profile, tumour microenvironment and epidemiology than that in smokers. Several risk factors have been associated with its occurrence, and the possibility of inherited predisposition is becoming clearer. A better understanding of this disease is essential for the future development of personalised screening, diagnosis and treatment approaches, with consequent reduction of mortality. In this review, we discuss historical studies of lung cancer in never-smokers and the currently available evidence of inherited predisposition to this disease.

Familial Lung Cancer: A Brief History from the Earliest Work to the Most Recent Studies

Lung cancer is the deadliest cancer in the United States, killing roughly one of four cancer patients in 2016. While it is well-established that lung cancer is caused primarily by environmental effects (particularly tobacco smoking), there is evidence for genetic susceptibility. Lung cancer has been shown to aggregate in families, and segregation analyses have hypothesized a major susceptibility locus for the disease. Genetic association studies have provided strong evidence for common risk variants of small-to-moderate effect. Rare and highly penetrant alleles have been identified by linkage studies, including on 6q23-25. Though not common, some germline mutations have also been identified via sequencing studies. Ongoing genomics studies aim to identify additional high penetrance germline susceptibility alleles for this deadly disease.

R331W Missense Mutation of Oncogene YAP1 Is a Germline Risk Allele for Lung Adenocarcinoma With Medical Actionability

PURPOSE

Adenocarcinoma is the most dominant type of lung cancer in never-smoker patients. The risk alleles from genome-wide association studies have small odds ratios and unclear biologic roles. Here we have taken an approach featuring suitable medical actionability to identify alleles with low population frequency but high disease-causing potential.

PATIENTS AND METHODS

Whole-genome sequencing was performed for a family with an unusually high density of lung adenocarcinoma with available DNA from the affected mother, four affected daughters, and one nonaffected son. Candidate risk alleles were confirmed by matrix-assisted laser desorption ionization time of flight mass spectroscopy. Validation was conducted in an external cohort of 1,135 participants without cancer and 1,312 patients with lung adenocarcinoma. Family follow-ups were performed by genotyping the relatives of the original proband and the relatives of the identified risk-allele carriers. Low-dose computed tomography scans of the chest were evaluated for lung abnormalities.

RESULTS

YAP1 R331W missense mutation from the original family was identified and validated in the external controls and the cohort with lung adenocarcinoma. The YAP1 mutant-allele carrier frequency was 1.1% in patients with lung adenocarcinoma compared with 0.18% in controls (P = .0095), yielding an odds ratio (adjusted for age, sex, and smoking status) of 5.9. Among the relatives, YAP1-mutant carriers have overwhelmingly higher frequencies of developing lung adenocarcinoma or ground-glass opacity lung lesions than those who do not carry the mutation (10:0 v 1:7; P < .001). YAP1 mutation was shown to increase the colony formation ability and invasion potential of lung cancer cells.

CONCLUSION

These results implicated YAP1 R331W as an allele predisposed for lung adenocarcinoma with high familial penetrance. Low-dose computed tomography scans may be recommended to this subpopulation, which is at high risk for lung cancer, for personalized prevention and health management.

Epidemiology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Ever since a lung cancer epidemic emerged in the mid-1900 s, the epidemiology of lung cancer has been intensively investigated to characterize its causes and patterns of occurrence. This report summarizes the key findings of this research.

METHODS

A detailed literature search provided the basis for a narrative review, identifying and summarizing key reports on population patterns and factors that affect lung cancer risk.

RESULTS

Established environmental risk factors for lung cancer include smoking cigarettes and other tobacco products and exposure to secondhand tobacco smoke, occupational lung carcinogens, radiation, and indoor and outdoor air pollution. Cigarette smoking is the predominant cause of lung cancer and the leading worldwide cause of cancer death. Smoking prevalence in developing nations has increased, starting new lung cancer epidemics in these nations. A positive family history and acquired lung disease are examples of host factors that are clinically useful risk indicators. Risk prediction models based on lung cancer risk factors have been developed, but further refinement is needed to provide clinically useful risk stratification. Promising biomarkers of lung cancer risk and early detection have been identified, but none are ready for broad clinical application.

CONCLUSIONS

Almost all lung cancer deaths are caused by cigarette smoking, underscoring the need for ongoing efforts at tobacco control throughout the world. Further research is needed into the reasons underlying lung cancer disparities, the causes of lung cancer in never smokers, the potential role of HIV in lung carcinogenesis, and the development of biomarkers.

Genomic landscape of non-small cell lung cancer in smokers and never-smokers

We report the results of whole-genome and transcriptome sequencing of tumor and adjacent normal tissue samples from 17 patients with non-small cell lung carcinoma (NSCLC). We identified 3,726 point mutations and more than 90 indels in the coding sequence, with an average mutation frequency more than 10-fold higher in smokers than in never-smokers. Novel alterations in genes involved in chromatin modification and DNA repair pathways were identified, along with DACH1, CFTR, RELN, ABCB5, and HGF. Deep digital sequencing revealed diverse clonality patterns in both never-smokers and smokers. All validated EFGR and KRAS mutations were present in the founder clones, suggesting possible roles in cancer initiation. Analysis revealed 14 fusions, including ROS1 and ALK, as well as novel metabolic enzymes. Cell-cycle and JAK-STAT pathways are significantly altered in lung cancer, along with perturbations in 54 genes that are potentially targetable with currently available drugs.

NBS1 Heterozygosity and Cancer Risk

Biallelic mutations in the NBS1 gene are responsible for the Nijmegen breakage syndrome (NBS), a rare autosomal recessive disorder characterized by chromosome instability and hypersensitivity to ionising radiation (IR). Epidemiological data evidence that the NBS1 gene can be considered a susceptibility factor for cancer development, as demonstrated by the fact that almost 40% of NBS patients have developed a malignancy before the age of 21. Interestingly, also NBS1 heterozygotes, which are clinically asymptomatic, display an elevated risk to develop some types of malignant tumours, especially breast, prostate and colorectal cancers, lymphoblastic leukaemia, and non-Hodgkin's lymphoma (NHL). So far, nine mutations in the NBS1 gene have been found, at the heterozygous state, in cancer patients. Among them, the 657del5, the I171V and the R215W mutations are the most frequently described. The pathogenicity of these mutations is presumably connected with their occurrence in the highly conserved BRCT tandem domains of the NBS1 protein, which are present in a large superfamily of proteins, and are recognized as major mediators of processes related to cell-cycle checkpoint and DNA repair.This review will focus on the current state-of-knowledge regarding the correlation between carriers of NBS1 gene mutations and the proneness to the development of malignant tumours.

Lung cancer incidence and survival in chromium exposed individuals with respect to expression of anti-apoptotic protein survivin and tumor suppressor P53 protein

OBJECTIVE

Workers chronically exposed to hexavalent chromium have elevated risk of lung cancer. Our study investigates the incidence of lung cancer types, age at onset of the disease, and survival time among chromium exposed workers with respect to the expression of anti-apoptotic p53 and pro-apoptotic survivin proteins.

MATERIAL AND METHODS

67 chromium exposed workers and 104 male controls diagnosed with lung cancer were analyzed. The mean exposure time among workers was 16.7 ±10.0(SD) years (range 1- 41 years). To investigate the possible regulation of survivin by p53 we examined the expression of both proteins using immohistochemical visualization.

RESULTS

Chromium exposure significantly decreases the age of onset of the disease by 3.5 years (62.2 ±9.1 in the exposed group vs. 65.7 ±10.5 years in controls; P=0.018). Small cell lung carcinoma (SCLC) amounted for 25.4% of all cases in chromium exposed workers and for 16.3% in non-exposed individuals. The mean survival time in the exposed group was 9.0 ±12.7 vs. 12.1 ±21.9 months in controls, but this difference was not significant. Survivin was predominantly expressed in both cell nucleus and cytoplasm, whereas p53 was expressed in the nucleus. There was a negative correlation between survivin and p53 expression. A decreased intensity of expression and fewer cells positive for survivin was detected in SCLC compared with other types of lung cancer. p53 was expressed in 94.1% and survivin in 79.6% of the samples analyzed.

CONCLUSION

The study calls attention to decreased expression of survivin, as opposed to p53, in small cell lung carcinoma.

Family history and lung cancer risk: international multicentre case-control study in Eastern and Central Europe and meta-analyses

Lung cancer is the most common neoplastic disease in Eastern and Central Europe. The role of hereditary factors in lung carcinogenesis is not fully understood. Family history (FH) of lung cancer and other tobacco-related cancers might be a strong predictor of the lung cancer risk. We investigated family history of cancer among first-degree relatives of 2,861 patients with lung cancer and 3,118 controls from the Czech Republic, Hungary, Poland, Romania, Russia, Slovakia, and United Kingdom within the IARC Multicenter Case-Control Study. Odds ratios (ORs) and 95% CI were calculated using logistic regression, adjusting for age, gender, study center, education, tobacco smoking, and number of first-degree relatives. In addition, we conducted a meta-analysis of 41 studies on FH of cancer and lung cancer risk. Positive FH of lung cancer increased risk of lung cancer with OR of 1.63 (95%CI: 1.31-2.01), and having two or more affected relatives with lung cancer further increased the risk of lung cancer with OR 3.60 (95%CI: 1.56-8.31). Among subjects aged less than 50, the OR for FH of lung cancer was 2.08 (95%CI: 1.18-3.63). The associations were generally stronger for squamous cell carcinoma and large cell carcinoma subtypes. Heterogeneity in results was not found with respect to smoking status and gender. A significant association was not observed for FH of other smoking-related tumors. The results of meta-analysis were consistent with that of our study with regard to young onset, non-smokers and histology. FH of lung cancer is a predictor of an increased risk of lung cancer, especially in subjects aged less than 50.

Tobacco, Genetic Susceptibility and Lung cancer

Exposure to tobacco smoke is an established risk factor for lung cancer, although a possible role for genetic susceptibility in the development of lung cancer has been inferred from familial clustering of the disease and segregation analysis. Findings of familial aggregation and statistical evidence for a major susceptibility gene have led to the search for high penetrant, rare, single genes and low penetrant, high frequency susceptibility genes for lung cancer. The relatively small number of linkage studies conducted to date, have identified potential lung cancer susceptibility loci on chromosomes 6q, 12p, and 19q. A variety of studies have examined single nucleotide polymorphisms of several low penetrant, high frequency genes encoding for enzymes involved in the metabolism of carcinogens and DNA damage repair, as likely candidate susceptibility genes. These studies have produced somewhat conflicting findings and, when significant, only modest associations have been reported. Relatively few studies have looked for potential gene-environment interactions, explored associations between two or more genetic polymorphisms or evaluated interactions between genetic polymorphisms and endogenous risk factors. Few large scale genome wide association studies conducted recently have provided evidence that common variation on chromosome 15q25.1, 5p15.33 and 6p21.33 influences lung cancer risk and cancer types with strong environmental risk factors. It is hoped that newer research strategies, selecting candidate genes within pathways and genotype at multiple markers within a gene, employing new technologies, may allow complete coverage of the variation within candidate genes in multiple pathways and to unravel the genetic susceptibility to lung cancer. This knowledge could, in turn, be used to identify persons at risk, to individualize treatments such as chemoprevention, to personalize harms of smoking and to motivate cessation.

FAMILIAL RISK FOR LUNG CANCER BY HISTOLOGY AND AGE OF ONSET: EVIDENCE FOR RECESSIVE INHERITANCE

The authors used the Swedish Family-Cancer Database to search for evidence for a genetic predisposition in lung cancer. Familial risks in offspring were increased for all lung cancer to 1.77 when a parent was affected with any lung cancers; the comparable risk among siblings was 2.15. At young age, risks between siblings were higher than those between offspring and parents for all histological types of lung cancer. The present data suggest that 1.7% of lung cancers up to age 68 years are heritable and probably due to a high-penetrant recessive gene or genes that predispose to tobacco carcinogens.

Family history of cancer and nonmalignant lung diseases as risk factors for lung cancer

Family history (FH) of lung cancer is an established risk factor for lung cancer, but the modifying effect of smoking in relatives has been rarely examined. Also, the role of FH of nonmalignant lung diseases on lung cancer risk is not well known. We examined the role of FH of cancer and nonmalignant lung diseases in lung cancer risk overall, and by personal smoking, FH of smoking and histology in 1,946 cases and 2,116 population-based controls within the Environment And Genetics in Lung cancer Etiology (EAGLE) study. Odds ratios (ORs) and 95% CI from logistic regression were calculated adjusting for age, gender, residence, education and cigarette smoking. FH of lung cancer in any family member was associated with increased lung cancer risk (OR = 1.57, 95% CI = 1.25-1.98). The odds associated with fathers', mothers' and siblings' history of lung cancer were 1.41, 2.14 and 1.53, respectively. The associations were generally stronger in never smokers, younger subjects and for the adenocarcinoma and squamous cell carcinoma subtypes. FH of chronic bronchitis and pneumonia was associated with increased (OR = 1.49, 95% CI = 1.23-1.80) and decreased (OR = 0.73, 95% CI = 0.61-0.87) lung cancer risk, respectively. FH of lung cancer and nonmalignant lung diseases affected lung cancer risk independently, and did not appear to be modified by FH of smoking.

Fine mapping of chromosome 6q23-25 region in familial lung cancer families reveals RGS17 as a likely candidate gene

PURPOSE

We have previously mapped a major susceptibility locus influencing familial lung cancer risk to chromosome 6q23-25. However, the causal gene at this locus remains undetermined. In this study, we further refined this locus to identify a single candidate gene, by fine mapping using microsatellite markers and association studies using high-density single nucleotide polymorphisms (SNP).

EXPERIMENTAL DESIGN

Six multigenerational families with five or more affected members were chosen for fine-mapping the 6q linkage region using microsatellite markers. For association mapping, we genotyped 24 6q-linked cases and 72 unrelated noncancer controls from the Genetic Epidemiology of Lung Cancer Consortium resources using the Affymetrix 500K chipset. Significant associations were validated in two independent familial lung cancer populations: 226 familial lung cases and 313 controls from the Genetic Epidemiology of Lung Cancer Consortium, and 154 familial cases and 325 controls from Mayo Clinic. Each familial case was chosen from one high-risk lung cancer family that has three or more affected members.

RESULTS

A region-wide scan across 6q23-25 found significant association between lung cancer susceptibility and three single nucleotide polymorphisms in the first intron of the RGS17 gene. This association was further confirmed in two independent familial lung cancer populations. By quantitative real-time PCR analysis of matched tumor and normal human tissues, we found that RGS17 transcript accumulation is highly and consistently increased in sporadic lung cancers. Human lung tumor cell proliferation and tumorigenesis in nude mice are inhibited upon knockdown of RGS17 levels.

CONCLUSION

RGS17 is a major candidate for the familial lung cancer susceptibility locus on chromosome 6q23-25.

DNA repair capacity and lung cancer risk in never smokers

Besides secondhand smoke exposure, few other risk factors for lung cancer in lifetime never smokers have been identified. We present the estimates of lung cancer risk associated with suboptimal DNA repair capacity (DRC) measured by the host-cell reactivation assay in lifetime never smokers using data from 219 cases and 309 matched controls enrolled in a case-control study. Suboptimal DRC level (below the control median) conferred a significantly increased lung cancer risk in never smokers [odds ratio, 1.92; 95% confidence interval (95% CI), 1.3-2.9; P = 0.0024]. There was a 3.38-fold risk for individuals with DRC below the first quartile (95% CI, 1.8-6.3) compared with individuals with DRC above the third quartile. Secondhand smoke exposure in individuals with DRC below the control median was associated with a 3.81-fold risk of lung cancer (95% CI, 2.3-6.4). A 2.49-fold (95% CI, 1.1-5.6) risk was noted for the joint effects of lung cancer family history in first-degree relatives and suboptimal DRC. Relatives of probands (cases and controls) with lowest DRC (below the first quartile) were significantly more likely to be diagnosed with lung cancer (odds ratio, 2.69; 95% CI, 1.1-6.7) compared with relatives of probands with the most proficient DRC (above the third quartile). Relatives of probands with suboptimal (below the control median) versus proficient DRC also had an earlier age at diagnosis with lung cancer, although the only statistically significant difference was in female relatives (55.4 versus 67.7 years; P = 0.03).

Familial aggregation of common sequence variants on 15q24-25.1 in lung cancer

Three recent genome-wide association studies identified associations between markers in the chromosomal region 15q24-25.1 and the risk of lung cancer. We conducted a genome-wide association analysis to investigate associations between single-nucleotide polymorphisms (SNPs) and the risk of lung cancer, in which we used blood DNA from 194 case patients with familial lung cancer and 219 cancer-free control subjects. We identified associations between common sequence variants at 15q24-25.1 (that spanned LOC123688 [a hypothetical gene], PSMA4, CHRNA3, CHRNA5, and CHRNB4) and lung cancer. The risk of lung cancer was more than fivefold higher among those subjects who had both a family history of lung cancer and two copies of high-risk alleles rs8034191 (odds ratio [OR] = 7.20, 95% confidence interval [CI] = 2.21 to 23.37) or rs1051730 (OR = 5.67, CI = 2.21 to 14.60, both of which were located in the 15q24-25.1 locus, than among control subjects. Thus, further research to elucidate causal variants in the 15q24-25.1 locus that are associated with lung cancer is warranted.

Do genetic factors protect for early onset lung cancer? A case control study before the age of 50 years

BACKGROUND

Early onset lung cancer shows some familial aggregation, pointing to a genetic predisposition. This study was set up to investigate the role of candidate genes in the susceptibility to lung cancer patients younger than 51 years at diagnosis.

METHODS

246 patients with a primary, histologically or cytologically confirmed neoplasm, recruited from 2000 to 2003 in major lung clinics across Germany, were matched to 223 unrelated healthy controls. 11 single nucleotide polymorphisms of genes with reported associations to lung cancer have been genotyped.

RESULTS

Genetic associations or gene-smoking interactions was found for GPX1(Pro200Leu) and EPHX1(His113Tyr). Carriers of the Leu-allele of GPX1(Pro200Leu) showed a significant risk reduction of OR = 0.6 (95% CI: 0.4-0.8, p = 0.002) in general and of OR = 0.3 (95% CI:0.1-0.8, p = 0.012) within heavy smokers. We could also find a risk decreasing genetic effect for His-carriers of EPHX1(His113Tyr) for moderate smokers (OR = 0.2, 95% CI:0.1-0.7, p = 0.012). Considered both variants together, a monotone decrease of the OR was found for smokers (OR of 0.20; 95% CI: 0.07-0.60) for each protective allele.

CONCLUSION

Smoking is the most important risk factor for young lung cancer patients. However, this study provides some support for the T-Allel of GPX1(Pro200Leu) and the C-Allele of EPHX1(His113Tyr) to play a protective role in early onset lung cancer susceptibility.

Assessing the relationship between lung cancer risk and emphysema detected on low-dose CT of the chest

RATIONALE

Identification of risk factors for lung cancer can help in selecting patients who may benefit the most from smoking cessation interventions, early detection, or chemoprevention.

OBJECTIVE

To evaluate whether the presence of emphysema on low-radiation-dose CT (LDCT) of the chest is an independent risk factor for lung cancer.

METHODS

The study used data from a prospective cohort of 1,166 former and current smokers participating in a lung cancer screening study. All individuals underwent a baseline LDCT and spirometry followed by yearly repeat LDCT studies. The incidence density of lung cancer among patients with and without emphysema on LDCT was estimated. Stratified and multiple regression analyses were used to assess whether emphysema is an independent risk factor for lung cancer after adjusting for age, gender, smoking history, and the presence of airway obstruction on spirometry.

RESULTS

On univariate analysis, the incidence density of lung cancer among individuals with and without emphysema on LDCT was 25.0 per 1,000 person-years and 7.5 per 1,000 person-years, respectively (risk ratio [RR], 3.33; 95% confidence interval [CI], 1.41 to 7.85). Emphysema was also associated with increased risk of lung cancer when the analysis was limited to individuals without airway obstruction on spirometry (RR, 4.33; 95% CI, 1.04 to 18.16). Multivariate analysis showed that the presence of emphysema (RR, 2.51; 95% CI, 1.01 to 6.23) on LDCT but not airway obstruction (RR, 2.10; 95% CI, 0.79 to 5.58) was associated with increased risk of lung cancer after adjusting for potential cofounders.

CONCLUSIONS

Results suggest that the presence of emphysema on LDCT is an independent risk factor for lung cancer.

Novel NBS1 heterozygous germ line mutation causing MRE11-binding domain loss predisposes to common types of cancer

DNA damage response (DDR) pathways maintain genomic stability. A 657del5 mutation of NBS1, a key DDR component, causing the rare cancer-predisposing Nijmegen breakage syndrome has been reported nearly exclusively in Slavic populations. In this study, we describe the first identification in a Japanese population of an unprecedented type of heterozygous NBS1 mutant, termed IVS11+2insT, lacking the MRE11- and ATM-binding site at the COOH terminus. Profoundly defective in crucial binding to MRE11, MDC1, BRCA1, and wild-type NBS1, the mutant caused impaired ATM phosphorylation in response to low-dose irradiation in a heterozygous state. Importantly, whereas IVS11+2insT was found in only 2 (0.09%) of 2,348 control subjects, it was identified in 2% (2 of 96) of heterozygotes with gastric cancer, 0.8% (3 of 376) of those with colorectal cancer, and 0.4% (2 of 532) of those with lung cancer, which were comparable to frequencies reported for other DDR-related genes known to confer cancer susceptibility. The presence of the heterozygous IVS11+2insT mutation seemed to be associated with an increased risk for gastrointestinal cancers, with an odds ratio of 12.6 and 95% confidence interval (95% CI) of 2.05 to 132.1 (P = 0.0001). The odds ratios separately calculated for gastric and colorectal cancers were 25.0 (95% CI, 1.78-346.0) and 9.43 (95% CI, 1.08-113.1), respectively. These findings suggest that IVS11+2insT is associated with an increased risk for the development of certain types of common cancers, warranting future investigation including detailed phenotypic characterization of age of onset and penetrance in heterozygotes, as well as screening in other ethnic groups.

Epidemiology of lung cancer: ACCP evidence-based clinical practice guidelines (2nd edition)

BACKGROUND

The objective of this study was to summarize the published literature concerning the epidemiology of lung cancer.

METHODS

A narrative review of published evidence was conducted, identifying and summarizing key reports that describe the occurrence of lung cancer in populations and factors that affect lung cancer risk.

RESULTS

In the United States, lung cancer remains the leading cause of cancer death in both men and women, even though an extensive list of modifiable risk factors has long been identified. The predominant cause of lung cancer is exposure to tobacco smoke, with active smoking causing most cases but passive smoking also contributing to the lung cancer burden.

CONCLUSIONS

The reductions in smoking prevalence in men that occurred in the late 1960s through the 1980s will continue to drive lung cancer mortality rates downward in men during the first portion of this century, but rates in women have not yet begun to decrease. Fortunately, exposures to major occupational respiratory carcinogens have largely been controlled, but the population is still exposed to environmental causes of lung cancer, including radon, the second leading cause of lung cancer death.

Aggregation of cancer among relatives of never-smoking lung cancer patients

The authors evaluated the familial aggregation of lung and other cancers in first-degree relatives of lung cancer patients self-reported to be lifetime never smokers. The data, derived from a large lung cancer case-control study, included 2,465 first-degree relatives of 316 never smoker lung cancer cases and 2,441 first-degree relatives of 318 never smoker controls, frequency matched to the cases on age, gender and ethnicity. The median age of the cases and the controls was 61 years, about 2/3 were women, and about 80% were Caucasian. Overall, there was a 25% excess risk [95% CI (1.05-1.50)] of any type of cancer among the first-degree relatives of cases, and case offspring exhibited a 2-fold excess cancer risk (1.03-4.10) compared with control offspring. There was also a 44% excess risk (1.05-1.97) of young onset cancers (before age 50) among relatives of cases. Smoking case relatives had an increased risk of any cancer [odds ratio (OR) = 1.36 (1.03-1.81)] and a 5.52-fold risk (1.19-25.51) of young onset lung cancer compared with smoking control relatives. Female case relatives had a 58% excess breast cancer risk (1.04-2.43), and case mothers a 2.57-fold breast cancer risk (1.16-4.24). A significant excess of testicular cancer was observed among case male relatives [OR = 12.32 (1.71-88.90)], although based on only 9 cases. The age at lung cancer diagnosis tended to be earlier in case relatives (61.4, SD = 12.9) compared with control relatives (66.2, SD = 11.4; p = 0.07). Our analysis provides further evidence for the importance of genetic factors for lung cancer in never smokers.

EGFR-T790M is a rare lung cancer susceptibility allele with enhanced kinase activity

The use of tyrosine kinase inhibitors (TKI) has yielded great success in treatment of lung adenocarcinomas. However, patients who develop resistance to TKI treatment often acquire a somatic resistance mutation (T790M) located in the catalytic cleft of the epidermal growth factor receptor (EGFR) enzyme. Recently, a report describing EGFR-T790M as a germ-line mutation suggested that this mutation may be associated with inherited susceptibility to lung cancer. Contrary to previous reports, our analysis indicates that the T790M mutation confers increased Y992 and Y1068 phosphorylation levels. In a human bronchial epithelial cell line, overexpression of EGFR-T790M displayed a growth advantage over wild-type (WT) EGFR. We also screened 237 lung cancer family probands, in addition to 45 bronchoalveolar tumors, and found that none of them contained the EGFR-T790M mutation. Our observations show that EGFR-T790M provides a proliferative advantage with respect to WT EGFR and suggest that the enhanced kinase activity of this mutant is the basis for rare cases of inherited susceptibility to lung cancer.

Lung Cancer in Never Smokers: A Review

Lung cancer is the leading cause of cancer-related death in the United States. Although tobacco smoking accounts for the majority of lung cancer, approximately 10% of patients with lung cancer in the United States are lifelong never smokers. Lung cancer in the never smokers (LCINS) affects women disproportionately more often than men. Only limited data are available on the etiopathogenesis, molecular abnormalities, and prognosis of LCINS. Several etiologic factors have been proposed for the development of LCINS, including exposure to radon, cooking fumes, asbestos, heavy metals, and environmental tobacco smoke, human papillomavirus infection, and inherited genetic susceptibility. However, the relative significance of these individual factors among different ethnic populations in the development of LCINS has not been well-characterized. Adenocarcinoma is the predominant histologic subtype reported with LCINS. Striking differences in response rates and outcomes are seen when patients with advanced non–small-cell lung cancer (NSCLC) who are lifelong never smokers are treated with epidermal growth factor receptor tyrosine kinase (EGFR-TK) inhibitors such as gefitinib or erlotinib compared with the outcomes with these agents in patients with tobacco-associated lung cancer. Interestingly, the activating mutations in the EGFR-TK inhibitors have been reported significantly more frequently in LCINS than in patients with tobacco-related NSCLC. This review will summarize available data on the epidemiology, risk factors, molecular genetics, management options, and outcomes of LCINS.

Genome-wide single nucleotide polymorphism analysis of lung cancer risk detects the KLF6 gene

A genome-wide association analysis using the Affymetrix 100K SNP array was carried out in a case-control study of lung cancer. Allele frequencies were estimated initially in DNA pools. Significant differences in allele frequency detected in the SNP array analysis were first tested in the same DNA pools by pyrosequencing and then by individual genotyping. DNA pooling analysis identified rs10508266 SNP, located approximately 12.5kb from the 5'-end of the KLF6 gene, as a marker showing significant association with lung cancer risk. Since the SNP was in significant linkage disequilibrium with the KLF6 gene region, we analyzed an Italian population of 338 lung adenocarcinoma cases and 335 controls for the possible role of the reported functional rs3750861 SNP, located 15.6kb from the rs10508266 SNP. The rs3750861 affects expression of KLF6 splicing variants in prostate cancer and we found that its rare allele is associated with reduced lung cancer risk (odds ratio, 0.5; 95% CI, 0.3-0.8). A Norwegian replication series of 265 non small cell lung cancer cases, and 356 controls, however, did not confirm the association. In light of the reported functional involvement of the KLF6 gene in lung cancer and in other cancer types and to the functional nature of the rs3750861 SNP, our results suggest a potential involvement of KLF6 polymorphisms in lung cancer risk, although additional studies in large series are needed to confirm our findings and to elucidate the mechanism by which the KLF6 SNPs influence lung cancer risk.

Family history and risk of lung cancer: age-at-diagnosis in cases and first-degree relatives

To investigate the little known risk of lung cancer at an early age when a first-degree relative has had such a diagnosis, 579 incident cases and 1157 population controls were studied in Liverpool between 1998 and 2004 using standardised questionnaires covering demography and lifestyle. A history of lung cancer in first-degree relatives was associated with a significantly increased risk in the proband where in both individuals the cancers were diagnosed before the age of 60 years (odds ratio (OR)=4.89; 95% confidence interval (CI): 1.47–16.25). A significantly elevated risk of lung cancer was also observed in association with a relative affected before the age of 60 years, regardless of age-at-onset of the disease (OR=2.08; 95% CI: 1.20–3.59). This finding is strongly consistent with a genetic component in early-onset lung cancer risk.

Association of the PDCD5 locus with lung cancer risk and prognosis in smokers

PURPOSE

Whole-genome scan association analysis was carried out to identify genetic variants predictive of lung cancer risk in smokers and to confirm the identified variants in an independent sample.

PATIENTS AND METHODS

A case-control study was performed using two pools consisting of DNA from 322 German smoking lung cancer patients and 273 healthy smoking controls, respectively. A replication study was carried out using 254 Italian lung adenocarcinoma (ADCA) patients and 235 healthy controls.

RESULTS

Patients with genotypes GG or CG for the rs1862214 single nucleotide polymorphism, 5' upstream of the programmed cell death 5 (PDCD5) gene, compared with those with the common genotype CC showed an increased risk of lung cancer (odds ratio, 1.6; 95% CI, 1.2 to 2.1) and a higher incidence of poor clinical stage disease (hazard ratio [HR], 1.9; 95% CI, 1.1 to 3.4; P = .023), nodal involvement (HR, 1.9; 95% CI, 1.1 to 3.6; P = .033), and short-term survivorship (HR, 1.8; 95% CI, 1.2 to 2.6, P = .003). PDCD5 mRNA expression levels were approximately 2.4-fold lower in lung ADCA as compared to normal lung tissue. Human NCI-H520 cancer cells transfected with PDCD5 cDNA showed decreased colony-forming ability.

CONCLUSION

These results suggest that the rs1862214 polymorphism in PDCD5 is predictive for lung cancer risk and prognosis, and that PDCD5 may represent a novel tumor suppressor gene influencing lung cancer.

Analysis of orthologous gene expression between human pulmonary adenocarcinoma and a carcinogen-induced murine model

Human adenocarcinoma (AC) is the most frequently diagnosed human lung cancer, and its absolute incidence is increasing dramatically. Compared to human lung AC, the A/J mouse-urethane model exhibits similar histological appearance and molecular changes. We examined the gene expression profiles of human and murine lung tissues (normal or AC) and compared the two species' datasets after aligning approximately 7500 orthologous genes. A list of 409 gene classifiers (P value <0.0001), common to both species (joint classifiers), showed significant, positive correlation in expression levels between the two species. A number of previously reported expression changes were recapitulated in both species, such as changes in glycolytic enzymes and cell-cycle proteins. Unexpectedly, joint classifiers in angiogenesis were uniformly down-regulated in tumor tissues. The eicosanoid pathway enzymes prostacyclin synthase (PGIS) and inducible prostaglandin E(2) synthase (PGES) were joint classifiers that showed opposite effects in lung AC (PGIS down-regulated; PGES up-regulated). Finally, tissue microarrays identified the same protein expression pattern for PGIS and PGES in 108 different non-small cell lung cancer biopsies, and the detection of PGIS had statistically significant prognostic value in patient survival. Thus, the A/J mouse-urethane model reflects significant molecular details of human lung AC, and comparison of changes in orthologous gene expression may provide novel insights into lung carcinogenesis.

Unlimited Access to Care: Effect on Racial Disparity and Prognostic Factors in Lung Cancer

STUDY OBJECTIVE

Evaluate the prognostic factors influencing lung cancer survival under a universal health care system and determine if access to care eliminates clinical outcome disparity.

DESIGN

Retrospective case series review.

BACKGROUND

Lung cancer survival is worse in men and in African Americans, thought to be related to poor general health in men and limited access to heath care in African Americans. The Military Health Care System, with unlimited access to care, provides an excellent setting for evaluating gender and racial disparities in lung cancer survival.

METHODS

Lung cancers diagnosed at Walter Reed Army Medical Center, from 1990 to 2000, were evaluated by chart review for age, gender, race, smoking history, cancer history, histology, stage, and completeness of resection.

RESULTS

Seven hundred thirteen Caucasians and 173 African Americans, 2:1 male predominance, had a 22% 5-year survival. Cox model analysis showed that male gender [hazard ratio (HR, 1.31) 95% confidence interval (95% CI), 1.02-1.68], advanced-stage disease (stage III: HR, 2.58; 95% CI, 1.57-4.26/stage IV: HR, 4.20; 95% CI, 2.51-7.41), and incomplete resection (HR, 4.06; 95% CI, 2.75-5.99) were predictors of poor outcome; whereas bronchoalveolar carcinoma features (HR, 0.35; 95% CI, 0.23-0.52) and smoking cessation >7 years (HR, 0.70; 95% CI, 0.49-0.99) were predictors of favorable outcome. No ethnic differences in survival were observed.

CONCLUSIONS

No racial disparities in survival when access to medical care is universal. Male gender, incomplete resection, and advanced stage are significant predictors of poor outcome in lung cancer.

Familial lung cancer: genetic susceptibility and relationship to chronic obstructive pulmonary disease

Lung cancer continues to be the leading cause of cancer death, and although most lung cancer is attributable to cigarette smoking, underlying genetic susceptibility is suggested by studies demonstrating familial aggregation. The first family linkage study of lung cancer has identified linkage of lung, laryngeal, and pharyngeal cancer in families to a region on chromosome 6q23-25. Because lung cancer and chronic obstructive pulmonary disease (COPD) are known to aggregate in families beyond shared risk associated with smoking, the linkage results are compared and contrasted with results from genomewide linkage and association studies and candidate gene studies searching for genes for lung cancer, lung function, and COPD. Linkage on chromosome 6q to both lung cancer and lung function, and on 12 to lung cancer, COPD, and lung function, together with overlap in candidate genes for these outcomes, suggests that future research into underlying genetic mechanisms of lung disease would benefit from broadening the collection of family history data and better defining the "high risk" population. As familial risk of lung disease is better defined, referral into screening programs and prevention trials can be better targeted to reach families with both a history of lung cancer and COPD.

An association between glutathione S-transferase P1 gene polymorphism and younger age at onset of lung carcinoma

BACKGROUND

Among the genes that encode the glutathione S-transferase (GST) superfamily of Phase 2 metabolizing enzymes, GSTP1 has the highest expression in the lung. The polymorphic GSTP1 gene encodes glutathione S-transferase pi, which is an enzyme that detoxifies cigarette carcinogens, such as benzo-[a]-pyrene. The variant GSTP1 GG genotype is associated with lower enzymatic activity and higher DNA adduct levels in human lymphocytes compared with the AA genotype.

METHODS

The authors evaluated the association of GSTP1 genotypes with lung cancer in 1921 cases and 1343 controls of Caucasian descent by using polymerase chain reaction-restriction fragment length polymorphism techniques. The results were analyzed with multiple logistic regression adjusting for age, gender, smoking status, and pack-years. To investigate specifically the subset of younger lung cancer patients and controls, the effect of age (either as a dichotomous or continuous variable in separate models) was analyzed as a modifying factor of the association between the GSTP1 polymorphism and lung cancer.

RESULTS

The GSTP1 GG genotype was not associated with an overall increased risk of lung cancer (adjusted odds ratio, 1.02; 95% confidence interval [95% CI], 0.78-1.34) compared with the GSTP1 AA genotype. In both models that evaluated the gene-age interaction, an overall statistically significant interaction (P < .01) was observed between age and the GG genotype. However, for the model that included age as a dichotomous variable, the odds ratio of lung cancer risk with the GG genotype compared with the AA among individuals age </=50 years was 2.67 (95% CI, 1.36-5.22); in older individuals, the risk was 0.87 (95% CI, 0.65-1.2).

CONCLUSIONS

The GSTP1 GG genotype was associated with increased lung cancer susceptibility among younger study participants.

Familial multiple primary lung cancers: a population-based analysis from Sweden

Multiple primary cancers arise because of inherited or acquired deficiencies, and their causes may depend on the first primary cancer, or they may be entirely independent. We used a nation-wide family dataset to search for evidence for a genetic predisposition to lung cancer. The Swedish Family-Cancer Database includes all Swedes born in 1932 and later with their parents, totalling over 10.2 million individuals. Cancer cases were retrieved from the Swedish Cancer Registry up to year 2000. Standardized incidence ratios (SIR) and 95% confidence limits (CI) were calculated for first and second primary lung cancers by a family history. The incidence of second primary lung cancer was nine times higher among cases with familial lung cancer compare to that of first primary lung cancer. The proportion of multiple primary lung cancer patients with family history for lung cancer was 4.7% (9/190) for men and 6.5% (5/77) for women. Lung cancer patients with a family history of lung cancer were at a significantly increased risk for subsequent primary lung cancer among both men (SIR=9.89, 95%CI 4.48-18.66) and women (SIR=17.86, 95%CI 5.63-42.00). The corresponding SIRs in patients without a family history were 2.04 (95%CI 1.75-2.36) and 5.10 (95%CI 3.99-6.43) for men and women, respectively. The present study suggests that the development from the first primary lung cancer to the second primary lung cancer may be more strongly affected by genetic factor than the first primary lung cancer.

Inherited predisposition to early onset lung cancer according to histological type

The role of hereditary factors in lung cancer is less well understood than in many other human neoplastic diseases. We used a nation-wide family dataset to search for evidence for a genetic predisposition in lung cancer. The Swedish Family-Cancer Database includes all Swedes born in 1932 and later (0- to 68-year-old offspring) with their parents, totaling over 10.2 million individuals. Cancer cases were retrieved from the Swedish Cancer Registry up to year 2000. Standardized incidence ratios (SIR) and 95% confidence limits (CI) were calculated for age-specific familial risks in offspring by parental or sibling proband, separately. A Kappa test was used to examine the association between familial risk and histology. Compared to the rate of lung cancers among persons without family history, a high risk by parental family history in adenocarcinoma (2.03) and large cell carcinoma (2.14) was found, and only a slightly lower risk was found among patients with squamous cell carcinoma (1.63) and small cell carcinoma (1.55). Among siblings, an increased risk was shown for concordant adenocarcinoma and small cell carcinoma at all ages and for all histological types when cancer was diagnosed before age 50. At young age, risks between siblings were higher than those between offspring and parents. The present data suggest that a large proportion of lung cancers before age 50 years appears to be heritable and probably due to a high-penetrant recessive gene or genes that predispose to tobacco carcinogens; however, this hypothesis needs to be tested in segregation analysis with a large number of pedigrees.

Complex segregation analysis reveals a multigene model for lung cancer

Lung cancer risk is largely attributed to tobacco exposure, but genetic predisposition also plays an etiologic role. Several studies have investigated the involvement of genetic predisposition in lung cancer aggregation in affected families, although with inconsistent results. Some studies have provided evidence for Mendelian inheritance, whereas others have suggested that environmental models are most appropriate for lung cancer aggregation in families. To examine the genetic basis of lung cancer, we performed segregation analysis on 14,378 individuals from 1,561 lung cancer case families, allowing for the effects of smoking, sex, and age. Both a Mendelian decreasing model and a Mendelian codominant model were found to be the best fitting models for susceptibility. However, when we modeled age-of-onset, all Mendelian models and the environmental model were rejected suggesting that multiple genetic factors (possibly multiple genetic loci and interactions) contribute to the age-of-onset of lung cancer. The results provide evidence that multiple genetic factors contribute to lung cancer and may act as a guide in further studies to localize susceptibility genes in lung cancer.

Pas1 haplotype-dependent genetic predisposition to lung tumorigenesis in rodents: a meta-analysis

Rodent species and strains show wide variations in susceptibility to lung tumorigenesis. In mice, hierarchical clustering of 29 inbred laboratory strains by pulmonary adenoma susceptibility 1 (Pas1) locus polymorphisms separated the strains into either an A/J- or a C57BL/6J-type Pas1 haplotype. A pooled analysis (including >8500 mice) of studies on spontaneous and chemically induced lung tumorigenesis in these strains revealed a significantly higher risk of spontaneous lung tumors [odds ratio (OR) 12.17; 95% confidence interval (CI) 9.00-16.45] as well as of chemically induced lung tumors (OR 15.14; 95% CI 12.51-18.31) in the A/J-type haplotype. Strain differences were observed with six different carcinogens, suggesting that Pas1 locus activity is carcinogen-independent. Thus, the present meta-analysis indicates a link between the genetic control of spontaneous and chemically induced lung tumor susceptibility in mice. The Pas1 susceptibility allele is frequent in the population of inbred mouse strains, whereas a counterpart appears to be absent or rare in rat and hamster strains. These findings might help in the interpretation of results of rodent carcinogenicity bioassays and assessing the risk of lung carcinogenesis from chemicals.

A major lung cancer susceptibility locus maps to chromosome 6q23-25

Lung cancer is a major cause of death in the United States and other countries. The risk of lung cancer is greatly increased by cigarette smoking and by certain occupational exposures, but familial factors also clearly play a major role. To identify susceptibility genes for familial lung cancer, we conducted a genomewide linkage analysis of 52 extended pedigrees ascertained through probands with lung cancer who had several first-degree relatives with the same disease. Multipoint linkage analysis, under a simple autosomal dominant model, of all 52 families with three or more individuals affected by lung, throat, or laryngeal cancer, yielded a maximum heterogeneity LOD score (HLOD) of 2.79 at 155 cM on chromosome 6q (marker D6S2436). A subset of 38 pedigrees with four or more affected individuals yielded a multipoint HLOD of 3.47 at 155 cM. Analysis of a further subset of 23 multigenerational pedigrees with five or more affected individuals yielded a multipoint HLOD score of 4.26 at the same position. The 14 families with only three affected relatives yielded negative LOD scores in this region. A predivided samples test for heterogeneity comparing the LOD scores from the 23 multigenerational families with those from the remaining families was significant (P=.007). The 1-HLOD multipoint support interval from the multigenerational families extends from C6S1848 at 146 cM to 164 cM near D6S1035, overlapping a genomic region that is deleted in sporadic lung cancers as well as numerous other cancer types. Parametric linkage and variance-components analysis that incorporated effects of age and personal smoking also supported linkage in this region, but with somewhat diminished support. These results localize a major susceptibility locus influencing lung cancer risk to 6q23-25.

Role of imbalance between neutrophil elastase and alpha 1-antitrypsin in cancer development and progression

Neutrophil elastase and alpha 1-antitrypsin are a pair of protease and protease inhibitor counterparts. The imbalance between the two counterparts is generally thought to cause tissue damage, which could create a favourable tissue environment for carcinogens and tumour progression. Laboratory research and clinical findings have indicated that a deficiency in alpha1-antitrypsin is associated with increased risk of liver cancer, bladder cancer, gall bladder cancer, malignant lymphoma, and lung cancer. Conversely, raised concentrations of neutrophil elastase might promote the development, invasion, and metastasis of many cancers. Several mechanisms of carcinogenesis have been postulated. Excess neutrophil elastase might facilitate cancer development by causing tissue damage and air trapping, which foster longer carcinogen exposure, might promote cancer progression by degrading the intercellular matrix barrier, and might directly lead to cancer development through the tumour-necrosis-factor signalling pathway.

Cancer aggregation and complex segregation analysis of families with female non-smoking lung cancer probands in Taiwan

Previous studies have found that having a first-degree blood relative with lung cancer was a possible predictor of lung cancer risk, but some studies have indicated that the association is non-significant or only significant for a subset of the studied population. To determine the familial aggregation and whether there is any evidence for a gene controlling the susceptibility to developing lung cancer in female non-smokers, multiple logistic regression methods for estimating covariate effects and maximum likelihood segregation analyses were performed using data from 216 female non-smoking lung cancer probands (2328 individuals) in a population-based case-control study. Having a family history of lung cancer was found to be a significant predictor of lung cancer for non-smoking females (Adjusted Odds Ratio (OR)=5.7, 95% Confidence Interval (CI)=1.9-16.9). Having a female relative with lung cancer (adjusted OR=14.4, 95% CI=2.7-75.5) was more strongly associated with the lung cancer risk than was having a male relative with lung cancer. This association was stronger for probands aged less than 60 years at onset (adjusted OR=11.2, 95% CI=2.2-56.9). All of the Mendelian models fitted the data significantly better than the sporadic (no major type) model or the environmental model (P<0.00l). The Mendelian codominant models provided the best fit of the data for the early onset probands and showed a stronger effect for a major susceptibility locus for non-smoking lung cancer probands. The results of this study provide evidence that a rare autosomal codominant gene may influence the risk lung cancer in non-smoker and is responsible for the familial aggregation observed in non-smoking lung cancer patients.

Polymorphisms in CYP1A1, GSTM1, GSTT1 and lung cancer below the age of 45 years

BACKGROUND

A genetic component of early-onset lung cancer has been suggested. The role of metabolic gene polymorphisms has never been studied in young lung cancer cases. Phase 1 and Phase 2 gene polymorphisms are involved in tobacco carcinogens' metabolism and therefore in lung cancer risk.

METHODS

The effect of metabolic gene polymorphisms on lung cancer at young ages was studied by pooling data from the Genetic Susceptibility to Environmental Carcinogens (GSEC) database. All primary lung cancer cases of both sexes who were Caucasian and </=45 years of age at diagnosis, and the corresponding controls were selected. We obtained 261 cases and 1452 controls.

RESULTS

There was a marginally significant association between lung cancer and GSTT1 null genotype (OR=1.2; 95% CI:1.0-1.6), and a significant association between lung cancer and the homozygous CYP1A1 Msp1 variant allele (CYP1A1*2A and *2B) genotype (OR=4.7 95% CI:1.2-19.0). When data were stratified by smoking status, the association between CYP1A1 genotype and lung cancer was confined to never smokers.

CONCLUSIONS

These results suggest that metabolic genetic factors play a role in lung cancer developing at young ages.

Role of the aryl hydrocarbon receptor in cell cycle regulation

Traditionally, the aryl hydrocarbon receptor (AHR) is considered to be a ligand-activated receptor and transcription factor responsible for the induction of drug-metabolizing enzymes. Its role in the combinatorial matrix of cell functions was neatly established long before the first report of an AHR cDNA sequence was published. Only recently, other functions of this protein have begun to be recognized. This review addresses novel findings relating to AHR functions that have resulted from experimental approaches markedly outside traditional receptor analyses. Here we examine the aspects of AHR biology relevant to its role in cell cycle regulation, from the activation of mitogen-activated protein kinases to the cross-talk between AHR and the RAS pathway and the functional significance of the interaction between AHR and the retinoblastoma protein. We have attempted to provide the reader with a balanced interpretation of the evidence, highlighting areas of consensus as well as areas still being contested.

Familial cancer aggregation and the risk of lung cancer

CONTEXT

Around 90% of lung cancer worldwide is attributable to cigarette smoking, although less than 20% of cigarette smokers develop lung cancer. Other factors such as diet, chronic lung diseases, occupation and possibly environmental agents also contribute to this cancer. Genetic factors seem to play a role in lung cancer, but the precise characteristics influencing lung cancer susceptibility are not known, since genetic factors are easily obscured by the strong environmental determinants of lung cancer, particularly smoking.

OBJECTIVE

To estimate the effect that cancer occurrence among first-degree relatives has on the risk of lung cancer.

DESIGN

Hospital-based case-control study.

SETTING

The metropolitan region of São Paulo, Brazil.

PARTICIPANTS

334 incident lung cancer cases and 578 controls matched by hospitals.

MAIN MEASUREMENTS

By means of a structured questionnaire, cases and controls were interviewed about cancer occurrence in first-degree relatives, tobacco smoking, exposure to passive smoking, occupation, migration and socioeconomic status. Non-conditional logistic regression was used to calculate the risk of familial cancer aggregation, the effect of cancer in first-degree relatives and smoking in conjunction, and for controlling confounders.

RESULTS

The adjusted odds ratio (OR) revealed a slight, but not statistically significant, excess risk of lung cancer for subjects with a history of lung cancer in relatives (OR 1.21; 95% confidence interval [CI] 0.50 - 2.92). The same was found among those with a history of other tobacco-related cancers in relatives (OR 1.36; 95% CI 0.87 - 2.14). A step gradient effect was observed regarding lung cancer risk, in accordance with increases in the number of pack-years of cigarette consumption. An interaction between familial cancer aggregation and tobacco smoking was detected.

CONCLUSIONS

A mildly elevated risk of lung cancer among persons with a positive history of lung and other tobacco-related cancers was observed. The finding of an interaction between the variables of familial cancer aggregation and smoking suggests that familial cancer aggregation could be considered as a marker of susceptibility, increasing the risk of lung cancer among smokers. These results improve our knowledge of lung carcinogenesis and can guide future cancer genetic studies.

Public health genetics: an emerging interdisciplinary field for the post-genomic era

Public health genetics is an exciting interdisciplinary area that brings all the public health sciences to bear on the emerging challenge of interpreting the medical and public health significance of genetic variation within populations. Sequencing of the human genome will generate an avalanche of genetic information to be linked with information about microbial, chemical, and physical exposures; nutrition, metabolism, lifestyle behaviors, and medications. The public health genetics mini-symposium in this volume includes articles dealing with educational innovations, host-pathogen interactions in infectious diseases, nutrition/genetic interactions in cancers, and population screening for hemochromatosis. Additional topics addressed here are ecogenetics and risk assessment, the genetics of unhealthful behaviors, and ethical and policy issues. Finally, a set of principles for community-based health research in populations is presented as a public health-oriented counterpart to the principle of autonomy and the practice of informed consent that have become key elements of ethics in medical care and medical research with individuals.

Familial aggregation of breast cancer with early onset lung cancer

Site-specific familial aggregation and evidence supporting Mendelian codominant inheritance have been shown in lung cancer. In characterizing lung cancer families, a number of other cancers have been observed. The current study evaluates whether first-degree relatives of early onset lung cancer cases are at increased risk of breast cancer. Families were identified through population-based lung cancer cases and controls under 40 years of age. Cases were ascertained through the Metropolitan Detroit SEER registry; controls through random-digit dialing. Data were available for 384 female relatives of 118 cases and 465 female relatives of 161 controls. Breast cancer in relatives was evaluated after adjusting for age, race, sex, and smoking status of each family member and the sex and age of the probands. A positive family history of early onset lung cancer increased breast cancer risk among first-degree relatives 5. 1-fold (95% CI, 1.7-15.1). Relatives of cases with adenocarcinoma of the lung were at highest risk (RR = 6.3, 95% CI 2.0-20). Mean age of breast cancer diagnosis among relatives of cases was 52.2 years and not statistically different from relatives of controls. Three case families also reported early ovarian cancers (mean age of diagnosis of 35 years). These findings suggest that shared susceptibility genes may act to increase risk of early onset lung and breast cancer in families.