Occupational risks for lung cancer among nonsmokers

Lung cancer in never smokers in the UK Million Women Study

To assess directly the effects of various risk factors on lung cancer incidence among never smokers, large prospective studies are needed. In a cohort of 1.2 million UK women without prior cancer, half (634,039) reported that they had never smoked. Mean age at recruitment was 55 (SD5) years, and during 14 (SD3) years of follow-up, 0.2% (1,469) of these never smokers developed lung cancer. Cox regression was used to estimate relative risks (RRs) of lung cancer for 34 potential risk factors, of which 31 were nonsignificant (p > 0.05). The remaining three risk factors were associated with a significantly increased incidence of lung cancer in never smokers: non-white vs. white ethnicity (RR = 2.34, 95% CI 1.55-3.52, p < 0.001), asthma requiring treatment vs. not (RR = 1.32, 1.10-1.58, p = 0.003) and taller stature (height ≥ 165 cm vs. <160 cm: RR = 1.16, 1.03-1.32, p = 0.02). There was little association with other sociodemographic, anthropometric or hormonal factors, or with dietary intakes of meat, fish, fruit, vegetables and fiber. The findings were not materially affected by restricting the analyses to adenocarcinomas, the most common histological type among never smokers.

Joint effects of environmental exposures and familial susceptibility to lung cancer in Chinese never smoking men and women

OBJECTIVES

Previous epidemiological studies had limited power to investigate the joint effects of individual environmental risk factors and familial susceptibility to lung cancer. This study aimed to address this shortcoming.

METHODS

We recruited 345 never smoking lung cancer cases and 828 community referents. We developed a collective environmental exposure index by assigning a value of 1 to subjects at high risks regarding environmental risk factors and 0 otherwise, and then summed over using weights equivalent to the excess odds ratio. Potential additive and multiplicative interactions between environmental exposure index and family cancer history were examined.

RESULTS

Compared with "low environmental exposure and without family cancer history", the odds ratio was 6.80 (95% confidence interval = 3.31-13.98) for males who had high environmental exposures but without family cancer history, whereas it increased to 30.61 (95% confidence interval = 9.38-99.87) if they also had a positive family history. The corresponding associations became weaker in never smoking females. No multiplicative interaction was observed for both genders and an additive interaction was restricted among males.

CONCLUSIONS

This study developed a novel environmental exposure index that offers sufficient interest deserving further studies on the interactions between environmental exposures and familial susceptibility to lung cancer risk.

Pollution in the working place and social status: co-factors in lung cancer carcinogenesis

INTRODUCTION

Apart from the association with tobacco consumption, other factors of importance for prevention and early diagnosis of lung cancer have received little attention. We present a case-control study focusing on professional exposure to carcinogens and social status.

METHODS

A written questionnaire was completed by 551 consecutive patients with lung cancer and 494 patients with large bowel cancer. The groups were balanced regarding gender and age distribution. The questionnaire included data on place of birth, education, smoking history, diet and alcohol intake, body weight and height, occupation, housing conditions and family income. According to standard epidemiological criteria, professional exposure to carcinogens was classified as professions with exposure to confirmed lung cancer carcinogens, professions with exposure to suspected lung cancer carcinogens and other professions.

RESULTS

As expected, there were significant differences between the two groups regarding smoking status. While there were no significant differences in educational levels, more immigrants were among patients with lung cancer (17.9% vs 11.6%, p=0.005). On average, lung cancer patients had a lower body mass index (BMI) at 24.77, as compared to 26.14 for large bowel cancer (p=0.000). Lung cancer patients had lower income and poorer housing conditions; the bivariate difference was significant both for income levels (p=0.046) and type of residence (p=0.009). The proportion of patients working in professions with exposures to known carcinogens was 33.5% for lung cancer, and 17.1% for large bowel cancer (p=0.000). In the multivariate analysis, smoking (p=0.000), BMI (p=0.000) and type of occupation (p=0.001) were significant factors.

CONCLUSIONS

While there is no doubt about smoking in lung cancer carcinogenesis, professional exposure to carcinogens and belonging to lower socio-economic strata also play an important role.

Population Attributable Risk for Occupational Gancer in Italy

Population studies estimating the proportion of cancer attributable to occupation (PAR) in different geographical areas in Italy are reviewed. Studies using lists of industrial activities and occupations which are known or suspected to entail exposure to lung carcinogens gave lung cancer PARs between 5% and 36%. Those using job-exposure matrices estimated PARs of 3%-53%, with most of the values ranging between 17 and 33%. For bladder cancer, PARs ranged between 4% and 24%. The uses and limitations of calculating population attribultable risk are discussed.

Occupational exposure and lung cancer risk - Study in two different Romanian areas

Lung cancer is the most frequent neoplasm worldwide and the incidence in Constanta County is in continuous increasing. Occupation as a cause of lung cancer is common. The authors examined the relation between occupation and lung cancer in two patient cohorts from different areas of Romania: Constanta and Valcea. In 2005-2010, in Constanta and Valcea counties, 488 and 344 incident lung cancer cases were enrolled. Lifetime occupational histories (industry and job title) were coded by using standard international classifications and were translated into occupations known (list A) or suspected (list B) to be associated with lung cancer. An exposure excess of 14.6% for patients from Constanta ever employed in occupations known to be associated with lung cancer (list A) was found, with the largest contributions from the oil refinery and shipbuilding industries No overall excess was found for list B with the exception of bus and truck drivers (men) and launderers and dry cleaners (women), in both groups of patients. These results indicate that past exposure to occupational carcinogens remains an important determinant of lung cancer occurrence.

What proportion of lung cancer in never-smokers can be attributed to known risk factors?

Though tobacco smoking is the primary risk factor for lung cancer, a significant fraction of lung cancer deaths occur in lifetime nonsmokers. In this article, we calculate the burden of lung cancer in never-smokers attributable to previously identified risk factors in North America, Europe and China, using population-based estimates of exposure prevalence and estimates of relative risk derived from recently published meta-analyses. Population attributable fractions (PAFs) for individual risk factors ranged from 0.40 to 19.93%. Because of differences in the prevalence of exposures, the PAFs associated with several of the risk factors varied greatly by geographical region. Exposure to the selected risk factors appeared to explain a much larger proportion of lung cancer cases in never-smokers in China than in Europe and North America. Our results demonstrate the geographic variability of the epidemiology of lung cancer in never-smokers and highlight the need for further research in this area, particularly in Europe and North America.

Occupational risk factors have to be considered in the definition of high-risk lung cancer populations

BACKGROUND

The aim of this study was to compute attributable fractions (AF) to occupational factors in an area in North-Eastern France with high lung cancer rates and a past of mining and steel industry.

METHODS

A population-based case-control study among males aged 40-79 was conducted, including confirmed primary lung cancer cases from all hospitals of the study region. Controls were stratified by broad age-classes, district and socioeconomic classes. Detailed occupational and personal risk factors were obtained in face-to-face interviews. Cumulative occupational exposure indices were obtained from the questionnaires. Attributable fractions were computed from multiple unconditional logistic regression models.

RESULTS

A total of 246 cases and 531 controls were included. The odds ratios (ORs) adjusted on cumulative smoking and family history of lung cancer increased significantly with the cumulative exposure indices to asbestos, polycyclic aromatic hydrocarbons and crystalline silica, and with exposure to diesel motor exhaust. The AF for occupational factors exceeded 50%, the most important contributor being crystalline silica and asbestos.

CONCLUSION

These AFs are higher than most published figures. This can be because of the highly industrialised area or methods for exposure assessments. Occupational factors are important risk factors and should not be forgotten when defining high-risk lung cancer populations.

Risk of lung cancer and occupational history: results of a French population-based case-control study, the ICARE study

OBJECTIVES

To assess the risk of lung cancer associated with occupations and industries.

METHODS

A French population-based case-control study included 2923 cases and 3555 controls. Lifelong occupational history was collected. Two lists of occupations known (A) or suspected (B) to be associated with lung cancer were used. Occupations and industries not included in these lists were also explored.

RESULTS

Among men, the smoking-adjusted odds ratio was 1.97 for list A (attributable fraction: 12.3%), 1.4 for list B (due especially to carpenters/joiners and transport workers). Among unlisted occupations, excess risks were found for welders, plumbers, and several construction crafts. Odds ratios among women were elevated for list A, list B (due especially to launderers/dry cleaners), cleaners and hairdressers.

CONCLUSIONS

These results confirm the role of known occupations and give insight into new occupational risk factors among men and women.

Evaluation and treatment of patients with non-small cell lung cancer

Lung cancer is the most common cause of cancer-related death in the United States; however, recent clinical advances may change this outcome. New data on low-dose computed tomography for lung cancer screening, and technologic advances in surgery and radiation, have improved outcomes for those with early-stage disease. Identification of driver mutations in lung cancer has led to the development of molecular targeted therapy to improve survival of subsets of patients with metastatic disease. These advances now allow for treatment of many patients with lung cancer with comorbidities or poor performance status who would have had limited options in the past.

Lung cancer risk in painters: a meta-analysis

We conducted a meta-analysis to quantitatively compare the association between occupation as a painter and the incidence or mortality from lung cancer. PubMed and the reference lists of pertinent publications were searched and reviewed. For the meta-analysis, we used data from 47 independent cohort, record linkage, and case-control studies (from a total of 74 reports), including > 11,000 incident cases or deaths from lung cancer among painters. Three authors independently abstracted data and assessed study quality. The summary relative risk (meta-RR, random effects) for lung cancer in paint-ers was 1.35 [95% confidence interval (CI), 1.29-1.41; 47 studies] and 1.35 (95% CI, 1.21-1.51; 27 studies) after controlling for smoking. The relative risk was higher in never-smokers (meta-RR = 2.00; 95% CI, 1.09-3.67; 3studies) and persisted when restricted to studies that adjusted for other occupational exposures (meta-RR = 1.57; 95% CI, 1.21-2.04; 5 studies). These results support the conclusion that occupational exposures in painters are causally associated with the risk of lung cancer.

Silica dust, diesel exhaust, and painting work are the significant occupational risk factors for lung cancer in nonsmoking Chinese men

Background:

Few epidemiological studies have explored the associations between occupational exposures and lung cancer in lifelong nonsmoking men.

Methods:

We obtained lifetime occupational history and other relevant information for 132 newly diagnosed lung cancer cases among nonsmoking Chinese men and 536 nonsmoking community referents. Unconditional multiple logistic regression analysis was performed to estimate the odds ratio (OR) of lung cancer for specific occupational exposures.

Results:

Significantly increased lung cancer risk was found for nonsmoking workers occupationally exposed to silica dust (OR=2.58, 95% confidence interval (CI): 1.11, 6.01), diesel exhaust (OR=3.47, 95% CI: 1.08, 11.14), spray painting (OR=2.81, 95% CI: 1.14, 6.93), and nonspray painting work (OR=2.36, 95% CI: 1.04, 5.37). Silica dust exposure was associated with a significantly increased risk of adenocarcinoma (OR=2.91, 95% CI: 1.10, 7.68). We observed a positive gradient of all lung cancers and of adenocarcinoma with duration of employment for workers exposed to silica dust and spray painting.

Conclusion:

This study found an increased risk of lung cancer among nonsmoking Chinese men occupationally exposed to silica dust, diesel exhaust, and painting work.

Assessing environmental and occupational risk factors for lung cancer in Mexican-Americans

BACKGROUND

We investigated environmental and occupational exposures and smoking history (while controlling for demographics) in a population of Mexican-American lung cancer cases and controls from the Houston metropolitan area.

METHODS

Data were collected between 1991 and 2005 as part of an on-going multi-racial/ethnic, lung cancer case-control study. Cases included 212 Mexican-American lung cancer cases from UT MD Anderson Cancer Center. Controls (n = 328) were recruited from Houston's largest multispecialty group practice and frequency matched to the cases by age (± 5 years), sex, and ethnicity. Environmental and occupational factors were analyzed and odds ratios and 95% confidence intervals were calculated using logistic regression.

RESULTS

We detected elevated risks of lung cancer associated with pesticide exposure and found conventional and antimicrobial (e.g., sterilizers, disinfectants, antiseptics) pesticides were associated with an increased risk of lung cancer in Mexican-Americans (conventional pesticides and antimicrobial pesticides combined: OR = 1.80, 95% CI 1.13-2.86; conventional pesticides: OR = 2.05, 95% CI 1.23-2.39; antimicrobial pesticides: OR = 2.48, 95% CI 1.46-4.21).

CONCLUSIONS

Although we found over a two-fold increased risk of lung cancer among Mexican-Americans for pesticides, we could not identify individual pesticides. Our findings are an important preliminary step in identifying factors that are specifically associated with lung cancer risk among Mexican Americans.

Meta-analyses of occupational exposure as a painter and lung and bladder cancer morbidity and mortality 1950-2008

The International Agency for Research on Cancer (IARC) classified occupational painting as a human carcinogen based on lung and bladder cancers; however, no specific exposures were implicated. The authors conducted comprehensive meta-analyses of the epidemiological literature on occupational painting and these cancers. The authors abstracted study results and confounder information, and used quantile plots and regression models to evaluate heterogeneity and publication bias. Summary risk estimates were derived and sensitivity analyses performed to evaluate smoking, socioeconomic status (SES), and exposure variables. Where applicable, a Bayesian approach was used to externally adjust for smoking, a major risk factor for both cancers. For lung cancer cohort mortality studies, publication bias and heterogeneity were seen, and earlier studies reported higher risk estimates than later studies. Overall lung cancer summary risk estimates were 1.29 for case-control and 1.22 and 1.36 for cohort morbidity and mortality studies, respectively, and risk estimates for bladder cancer were 1.28 for case-control and 1.14 and 1.27 for cohort morbidity and mortality studies, respectively (all statistically significant). Risks did not differ between painters and mixed occupations. Nonsignificant summary estimates resulted for lung and bladder cancers when controlling for SES, or externally adjusting for smoking in lung cancer studies. Summary risks varied by control source for case-control studies. Residual confounding by smoking and SES, lack of exposure group effect, and publication bias limit the ability of the meta-analyses to explain associations observed between occupational painting and lung and bladder cancers. Given the long latencies for lung and bladder cancers, these weak associations, if real, may not be elucidated through studies of occupational painting today.

Lung cancer risk in painters: a meta-analysis

OBJECTIVE

We conducted a meta-analysis to quantitatively compare the association between occupation as a painter and the incidence or mortality from lung cancer.

DATA SOURCES

PubMed and the reference lists of pertinent publications were searched and reviewed. For the meta-analysis, we used data from 47 independent cohort, record linkage, and case control studies (from a total of 74 reports), including > 11,000 incident cases or deaths from lung cancer among painters.

DATA EXTRACTION

Three authors independently abstracted data and assessed study quality.

DATA SYNTHESIS

The summary relative risk (meta-RR, random effects) for lung cancer in painters was 1.35 [95% confidence interval (CI), 1.291.41; 47 studies] and 1.35 (95% CI, 1.211.51; 27 studies) after controlling for smoking. The relative risk was higher in never-smokers (meta-RR = 2.00; 95% CI, 1.093.67; 3 studies) and persisted when restricted to studies that adjusted for other occupational exposures (meta-RR = 1.57; 95% CI, 1.212.04; 5 studies). The results remained robust when stratified by study design, sex, and study location and are therefore unlikely due to chance or bias. Furthermore, exposure response analyses suggested that the risk increased with duration of employment.

CONCLUSION

These results support the conclusion that occupational exposures in painters are causally associated with the risk of lung cancer.

Lung cancer and occupation in a population-based case-control study

The authors examined the relation between occupation and lung cancer in the large, population-based Environment And Genetics in Lung cancer Etiology (EAGLE) case-control study. In 2002-2005 in the Lombardy region of northern Italy, 2,100 incident lung cancer cases and 2,120 randomly selected population controls were enrolled. Lifetime occupational histories (industry and job title) were coded by using standard international classifications and were translated into occupations known (list A) or suspected (list B) to be associated with lung cancer. Smoking-adjusted odds ratios and 95% confidence intervals were calculated with logistic regression. For men, an increased risk was found for list A (177 exposed cases and 100 controls; odds ratio = 1.74, 95% confidence interval: 1.27, 2.38) and most occupations therein. No overall excess was found for list B with the exception of filling station attendants and bus and truck drivers (men) and launderers and dry cleaners (women). The authors estimated that 4.9% (95% confidence interval: 2.0, 7.8) of lung cancers in men were attributable to occupation. Among those in other occupations, risk excesses were found for metal workers, barbers and hairdressers, and other motor vehicle drivers. These results indicate that past exposure to occupational carcinogens remains an important determinant of lung cancer occurrence.

Lung cancer in never smokers: clinical epidemiology and environmental risk factors

More than 161,000 lung cancer deaths are projected to occur in the United States in 2008. Of these, an estimated 10 to 15% will be caused by factors other than active smoking, corresponding to 16,000 to 24,000 deaths annually. Thus lung cancer in never smokers would rank among the most common causes of cancer mortality in the United States if considered as a separate category. Slightly more than half of the lung cancers caused by factors other than active smoking occur in never smokers. As summarized in the accompanying article, lung cancers that occur in never smokers differ from those that occur in smokers in their molecular profile and response to targeted therapy. These recent laboratory and clinical observations highlight the importance of defining the genetic and environmental factors responsible for the development of lung cancer in never smokers. This article summarizes available data on the clinical epidemiology of lung cancer in never smokers, and several environmental risk factors that population-based research has implicated in the etiology of these cancers. Primary factors closely tied to lung cancer in never smokers include exposure to known and suspected carcinogens including radon, second-hand tobacco smoke, and other indoor air pollutants. Several other exposures have been implicated. However, a large fraction of lung cancers occurring in never smokers cannot be definitively associated with established environmental risk factors, highlighting the need for additional epidemiologic research in this area.

Occupational risk of lung cancer among lifetime non-smoking women in Shanghai, China

OBJECTIVES

Occupational lung carcinogens have been primarily studied in men. The aim of this study was to investigate occupational lung cancer risk in a cohort of Chinese non-smoking women.

METHODS

In 1996-2000, 71 067 non-smoking women who had held a job outside the home were interviewed for the prospective Shanghai Women's Health Study in China. Exposure to lung carcinogens was assessed by matching occupation and industry titles from lifetime occupational histories with lists of jobs identified by the International Agency for Research on Cancer to have potential exposure to: (1) known (A-list); or (2) suspected (B-list) carcinogens. In addition, similar occupational titles were grouped independent of the a priori defined lists. Relative risks (RRs) were calculated using Cox proportional hazards regression.

RESULTS

During follow-up through 2005, 219 incident lung cancer cases were diagnosed. Jobs on the A-list and B-list were held by 0.8-6.7% and 2.7-9.4% of the cohort, respectively. Overall, ever holding any job on the A-list or B-list was not associated with lung cancer incidence. Indications of excess risk were found for two subgroups: painters (A-list) and rubber workers (B-list) (RR = 2.0 and 1.7, respectively, p<or=0.1). An exploratory analysis of 35 occupational categories independent of the lists showed significantly increased risks for leather products/shoes, wood/paper products and miscellaneous production/transportation. The former two of these categories were similar to subgroups of the B-list, but broader than the specific a priori defined jobs.

CONCLUSIONS

Significantly elevated lung cancer risk was associated with employment in some broad occupational categories that also included jobs with potential exposure to suspected carcinogens (B-list). The results suggest that although similar exposures to those described on the B-list may play a role in this cohort of Chinese women, carcinogenic exposure may not be restricted only to the jobs on the B-list.

Meta- and pooled analysis of GSTP1 polymorphism and lung cancer: a HuGE-GSEC review

Lung cancer is the most common cancer worldwide. Polymorphisms in genes associated with carcinogen metabolism may modulate risk of disease. Glutathione S-transferase pi (GSTP1) detoxifies polycyclic aromatic hydrocarbons found in cigarette smoke and is the most highly expressed glutathione S-transferase in lung tissue. A polymorphism in the GSTP1 gene, an A-to-G transition in exon 5 (Ile105Val, 313A --> 313G), results in lower activity among individuals who carry the valine allele. The authors present a meta- and a pooled analysis of case-control studies that examined the association between this polymorphism in GSTP1 and lung cancer risk (27 studies, 8,322 cases and 8,844 controls and 15 studies, 4,282 cases and 5,032 controls, respectively). Overall, the meta-analysis found no significant association between lung cancer risk and the GSTP1 exon 5 polymorphism. In the pooled analysis, there was an overall association (odds ratio = 1.11, 95% confidence interval: 1.03, 1.21) between lung cancer and carriage of the GSTP1 Val/Val or Ile/Val genotype compared with those carrying the Ile/Ile genotype. Increased risk varied by histologic type in Asians. There appears to be evidence for interaction between amount of smoking, the GSTP1 exon 5 polymorphism, and risk of lung cancer in whites.

Occupation, gender, race, and lung cancer

OBJECTIVE

To examine associations between occupation and lung cancer by gender and race.

METHODS

We used data from the Maryland Lung Cancer Study of nonsmall cell lung carcinoma (NSCLC), a multicenter case control study, to estimate odds ratios (ORs) of NSCLC in different occupations.

RESULTS

After adjusting for smoking, environmental tobacco smoke, and other covariates, NSCLC ORs among women but not men were elevated in clerical-sales, service, and transportation-material handling occupations; ORs were significantly increased in all three categories (OR [95% confidence interval]: 4.07 [1.44 to 11.48]; 5.15 [1.62 to 16.34]; 7.82 [1.08 to 56.25], respectively), among black women, but only in transportation-material handling occupations (OR [95% confidence interval[: 3.43 [1.02 to 11.50]) among white women.

CONCLUSIONS

Women, especially black women, in certain occupations had increased NSCLC ORs.

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.

Lung cancer and occupation in nonsmokers: a multicenter case-control study in Europe

BACKGROUND

Tobacco smoking is the main cause for lung cancer worldwide, making it difficult to examine the carcinogenic role of other risk factors because of possible confounding by smoking. Therefore, the present study aimed to investigate the association between lung cancer and occupation independent of smoking.

METHODS

A case-control study of lung cancer was carried out between March 1998 and January 2002 in 16 centers from 7 European countries, including 223 never-smoking cases and 1039 controls. Information on lifestyle and occupation was obtained through detailed questionnaires. Job and industries were classified as entailing exposure to known or suspected carcinogens; in addition, expert assessment provided exposure estimates to specific agents.

RESULTS

The odds ratio of lung cancer among women employed for more than 12 years in suspected high-risk occupations was 1.75 (95% confidence interval = 0.63-4.85). A comparable increase in risk was not detected for employment in established high-risk occupations or among men. Increased risk of lung cancer was suggested among individuals exposed to nonferrous metal dust and fumes, crystalline silica, and organic solvents.

CONCLUSION

Occupations were found to play a limited role in lung cancer risk among never-smokers. Jobs entailing exposure to suspected lung carcinogens should receive priority in future studies among women. Nonferrous metal dust and fumes and silica may exert a carcinogenic effect independently from smoking.

Risk of second cancer after chronic lymphocytic leukemia

Smoking is not considered a risk factor for chronic lymphocytic leukemia (CLL) yet increased lung cancer risk has been reported for these patients. Little data exist on the temporal variation in lung cancer risk after CLL, or its histological composition. We investigated the occurrence of second cancers in a large cohort of CLL patients with particular emphasis on lung cancer and its major subtypes. We followed all patients diagnosed with CLL in Denmark in the period 1943-2003 (n = 12,373) for the occurrence of second cancers. The relative risk was expressed as the standardized incidence ratio (SIR), i.e. the ratio of observed to expected number of cancers, based on incidence rates for the Danish population. During follow-up 1,105 cancers occurred among the CLL patients (SIR = 1.59 (95% CI 1.50-1.69)). SIR for all cancers combined remained elevated more than 10 years after CLL (SIR = 1.80 (1.56-2.08)). Lung cancer occurred in 141 patients (SIR = 1.61 (1.37-1.90)). The relative risk of lung cancer did not vary by gender, or time of follow-up, but was higher in younger (SIR(<60 years) = 2.22 (1.62-3.06)) than in older (SIR(70-79 years) = 1.21 (0.88-1.68)) age-groups. Elevated risks were observed for adenocarcinoma (SIR = 2.20 (1.57-3.08)) and squamous cell carcinoma (SIR = 1.52 (1.06-2.17)) of the lung. We speculate that shared genetic risk factors may explain the accumulation of lung and other cancers in CLL patients.

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.

Overview of smoking and all cancers

Tobacco consumption has been clearly implicated in the causation of many cancer types, with irrefutable evidence to support the association in multiple organ systems. Tobacco cessation leads to reduced cancer risk and improved survival of those under treatment for their already established cancers. As understanding of the mechanisms by which tobacco products cause cancer increases, clinicians may be able to identify those at highest risk for tobacco-related malignancies and allow for more focused interventions toward risk reduction among current tobacco users. This article reviews the carcinogens present in tobacco products, the mechanisms by which tobacco causes cancer, and the various tumor types causally related to tobacco use.

Occupational and environmental exposures and lung cancer in an industrialised area in Italy

AIMS

To investigate the effects of occupational exposures and residence near to industrial sites on lung cancer mortality in an area in Italy.

METHODS

234 cases of lung cancer and 729 controls matched by sex, age, and date of death were enrolled. Environmental exposure was evaluated using historical residence data. A geographical information system was used to compute distances from residence to pollution source (cement factory, power plants, harbour) and an average distance was computed for each subject. Odds ratios (OR) and 95% confidence intervals (CI) in a logistic regression model were used to estimate the relative risk of lung cancer associated with the risk factors (smoking habits and occupational exposure) collected by questionnaire; ORs for distances from pollution sources and from city centre were computed, adjusting for smoking habits, education, and occupation.

RESULTS

Smoking habits (< or =10 cigarettes/day, OR = 2.28; 11-20, OR = 4.64; >20, OR = 6.61) and occupational exposure to asbestos (OR = 3.50) were significantly associated with lung cancer risk. Reported traffic level of area of residence and residence near the four sources were not associated with increased risk of lung cancer. There was a significantly increased risk for those residing outside the city centre, in the southern outskirts (OR = 1.51).

CONCLUSIONS

The increased lung cancer risk observed in the area can partly be explained by occupational exposures. The increased risk in the outskirts of the city is consistent with the results of dispersion models that indicate high levels of pollutant deposition in the same area.

The protective effect of the Mediterranean diet on lung cancer

There has been growing interest over recent years in the potential preventive role of the Mediterranean diet in the development of cardiovascular disease and cancer. The present study was designed to evaluate the relationship between the components of the Mediterranean diet and lung cancer. A hospital-based, case-control study of lung cancer was conducted on subjects aged 35+ yr living in the Lazio region and admitted to one of the main hospitals in Rome in the period from 1993 to 1996. Cases (n = 342) were patients with newly diagnosed primary lung cancer. Controls (n = 292) were recruited from departments of general surgery, orthopedics, ENT, and general medicine and were frequency matched by sex and age (+/-5 yr) to the cases. Exposure characteristics were obtained by interviewing study subjects. A self-administered food-frequency questionnaire was used. After careful control for several smoking variables, we found a protective effect for high consumption of carrots (odds ratio [OR] = 0.67, 95% confidence interval [CI] = 0.42-1.05), tomatoes (OR = 0.59, 95% CI = 0.34-1.03), white meat (OR = 0.66, 95% CI = 0.42-1.02), exclusive use of olive oil (OR = 0.67, 95% CI = 0.45-0.99), and regular consumption of sage (OR = 0.43, 95% CI = 0.29-0.65). In a multivariate model, considering all food items simultaneously, the protective effect of exclusive olive oil use and sage remained statistically significant. Our results indicate that some food items typical of the Mediterranean diet are associated with decreased lung cancer risk.

Analysis of nonresponse bias in a population-based case-control study on lung cancer

The objective of this study was to identify characteristics of nonrespondents and late respondents in a population-based case-control study on lung cancer conducted in the city of Turin (Italy). Information about demographic and socioeconomic variables of 634 cases and 859 controls who responded to an interview, as well as of 154 cases and 154 controls who did not respond were obtained from census and the public register of Turin. The socioeconomic level of nonrespondents was high in cases but low in controls. Late respondent controls (i.e., individuals who responded after contact through their general practitioner) had socioeconomic characteristics comparable with those of nonrespondents, while they were similar to respondents with respect to demographic variables. The interview of late respondents halved, from 14 to 7%, the magnitude of the bias introduced by nonresponse on the estimate of the association between educational level and lung cancer. Nonresponse, associated with socioeconomic status, is an important potential source of bias in population-based case-control studies, which should always be considered and discussed. The direction and magnitude of the bias can be quantified. General practitioners may contribute to decrease nonresponse bias. Caution should be used in inferring characteristics of nonrespondents on the basis of those of late respondents.

Risk factors for lung cancer among nonsmoking women

To evaluate risk factors for lung cancer in nonsmoking women, we used data of a case-control study conducted between 1991 and 1996 in Germany. A total of 234 female histologically confirmed lung cancer patients and 535 population controls who had never smoked more than 400 cigarettes in their lifetime were personally interviewed with respect to occupation, exposure to environmental tobacco smoke (ETS), family history of cancer, prior physician-diagnosed lung diseases or cancer and diet. One-year radon measurements in the last dwelling were performed. Odds ratios (OR) adjusted for age and region and 95% confidence intervals (CI) were calculated via logistic regression. When cumulative duration of exposure to ETS in hours was considered, the OR for high compared to not or low ETS exposed women was 2.62 (CI:1.35-5.06) for occupational exposure and OR=1.67 (CI:0.86-3.25) for spousal exposure, exhibiting a significant trend for ETS at work. Working more than 10 years in jobs or industries with known or suspected lung carcinogens was associated with OR=2.0 (CI:0.99-4.0). An elevated risk due to prior lung diseases was present for pneumonia (OR=1.6; CI:1.07-2.40) and tuberculosis (OR=1.6; CI:0.77-3.37). No significant increase in risk with increasing residential radon levels or with the presence of a family history of lung cancer was apparent. Protective effects were observed for high vs. low consumption of fresh vegetables (OR=0.5; CI:0.25-0.82) and cheese (OR=0.3, CI:0.21-0.55). ETS at work, occupational hazards and previous pneumonia may be risk factors for lung cancer in nonsmoking women, while a diet rich in fresh vegetables and cheese seems to be protective.

Occupational and environmental thoracic malignancies

Lung cancer is the most common thoracic malignancy caused by exposures at work and in the environment. The most unique thoracic malignancy is mesothelioma, because it is relatively rare and one of only a few neoplasms for which one specific inciting agent-asbestos-has been identified. Based on epidemiologic studies, approximately 15% of lung cancers in men and 5% of lung cancers in women are caused by occupational exposures. The International Agency for Research on Cancer has devised a rating system by which, based on animal and human data, they assign an agent, mixture, or exposure circumstance to one of five categories, ranging from group 1 (agent is carcinogenic to humans) to group 4 (agent is probably not carcinogenic to humans). Group 1 pulmonary carcinogens reviewed in this article include arsenic, asbestos, beryllium, bis (chloromethyl) ether, cadmium, chromium (IV), mustard gas, nickel, radon, and silica. The clinical presentation and pathology of lung cancers and mesothelioma caused by such exposures do not differ from those of cancers caused by other factors. The key to the recognition of a thoracic malignancy caused by workplace or environmental exposures is clinical suspicion and consideration of all causes for the disease present. Recognition of an exposure-related case of lung cancer or mesothelioma can aid in the identification of excess risk for a whole workforce or community and can lead to actions to reduce exposure, thus preventing future cases. In addition, such recognition allows the individuals struck by devastating illness to exercise their legal rights to compensation if so desired.

Epidemiology, etiology, and prevention of lung cancer

Over the past century, lung cancer has gone from an obscure disease to the leading cause of cancer death worldwide. Initially an epidemic disease among men in industrialized nations, lung cancer now has become the leading cancer killer in both sexes in the United States and an increasingly common disease of both sexes in developing countries. Lung cancer incidence largely mirrors smoking prevalence, with a latency period of several decades. Other important risk factors for the development of lung cancer include environmental exposure to tobacco smoke, radon, occupational carcinogens, and pre-existing nonmalignant lung disease. Studies in molecular biology have elucidated the role that genetic factors play in modifying an individual's risk for lung cancer. Although chemopreventive agents may be developed to prevent lung cancer, prevention of smoking initiation and promotion of smoking cessation are currently the best weapons to fight lung cancer. No other malignancy has been shown to have such a strong epidemiologic relation between a preventable behavior and incidence of disease. Despite this knowledge, more than 20% of all Americans smoke, and tobacco use is exploding in developing countries. Based on current and projected smoking patterns, it is anticipated that lung cancer will remain the leading cause of cancer death in the world for decades to come.

Lung cancer and cigarette smoking in Europe: an update of risk estimates and an assessment of inter-country heterogeneity

Ten case-control studies have been carried out in 6 European countries to investigate the major risk factors for lung cancer. Carcinogenic effect from cigarette smoke was the most relevant interest in our study, which has included 7,609 cases of lung cancer and 10,431 controls, mainly population based. The results indicate elevated odds ratios (ORs; 23.9 among men and 8.7 among women) with attributable risks exceeding 90% for men and close to 60% for women. A large, and statistically significant, variability of the results across countries was detected after adjusting for the most common confounding variables, and after controlling, at least in part, for the instability of the ORs due to the small number of non-smokers in some of the study subsets. This pattern of lung cancer risk associated with cigarettes smoke, across different European regions, reflects inherent characteristics of the studies as well as differences in smoking habits, particularly calendar periods of starting, and it is likely to have been influenced by effect modifiers like indoor radon exposure, occupation, air pollution and dietary habits.

Lung cancer in lifetime nonsmoking men - results of a case-control study in Germany

Epidemiological studies of lung cancer among nonsmoking men are few. This case-control study was conducted among lifetime nonsmoking men between 1990 and 1996 in Germany to examine lung cancer risk in relation to occupation, environmental tobacco smoke, residential radon, family history of cancer and previous lung disease. A total of 58 male cases with confirmed primary lung cancer and 803 male population controls who had never smoked more than 400 cigarettes in their lifetime were personally interviewed by a standardized questionnaire. In addition, 1-year radon measurements in the living and bedroom of the subjects' last dwelling were carried out. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Having ever worked in a job with known lung carcinogens was associated with a two-fold significantly increased lung cancer risk (OR = 2.2; CI = 1.0-5.0), adjusted for age and region. The linear trend test for lung-cancer risk associated with radon exposure was close to statistical significance, demonstrating an excess relative risk for an increase in exposure of 100 Bq m(-3)of 0.43 (P = 0.052). Nonsignificantly elevated effects of exposure to environmental tobacco smoke in public transportation and in social settings were observed. No associations with a family history of cancer or previous lung diseases were found. Our results indicate that occupational carcinogens and indoor radon may play a role in some lung cancers in nonsmoking men.