Risk of lung cancer following nonmalignant respiratory conditions: evidence from two case-control studies in Montreal, Canada

A systematic review of the epidemiology evidence on talc and cancer

Over the past several decades, there have been many epidemiology studies on talc and cancer published in the scientific literature, and several reviews and meta-analyses of talc and respiratory, female reproductive, and stomach cancers, specifically. To help provide a resource for the evaluation of talc as a potential human carcinogen, we applied a consistent set of examination methods and criteria for all epidemiology studies that examined the association between talc exposure (by various routes) and cancers (of various types). We identified 30 cohort, 35 case-control, and 12 pooled studies that evaluated occupational, medicinal, and personal-care product talc exposure and cancers of the respiratory system, the female reproductive tract, the gastrointestinal tract, the urinary system, the lymphohematopoietic system, the prostate, male genital organs, and the central nervous system, as well as skin, eye, bone, connective tissue, peritoneal, and breast cancers. We tabulated study characteristics, quality, and results in a systematic manner, and evaluated all cancer types for which studies of at least three unique populations were available in a narrative review. We focused on study quality aspects most likely to impact the interpretation of results. We found that only one study, of medicinal talc use, evaluated direct exposure measurements for any individuals, though some used semi-quantitative exposure metrics, and few studies adequately assessed potential confounders. The only consistent associations were with ovarian cancer in case-control studies and these associations were likely impacted by recall and potentially other biases. This systematic review indicates that epidemiology studies do not support a causal association between occupational, medicinal, or personal talc exposure and any cancer in humans.

Investigating causal associations between pneumonia and lung cancer using a bidirectional mendelian randomization framework

BACKGROUND

Pneumonia and lung cancer are both major respiratory diseases, and observational studies have explored the association between their susceptibility. However, due to the presence of potential confounders and reverse causality, the comprehensive causal relationships between pneumonia and lung cancer require further exploration.

METHODS

Genome-wide association study (GWAS) summary-level data were obtained from the hitherto latest FinnGen database, COVID-19 Host Genetics Initiative resource, and International Lung Cancer Consortium. We implemented a bidirectional Mendelian randomization (MR) framework to evaluate the causal relationships between several specific types of pneumonia and lung cancer. The causal estimates were mainly calculated by inverse-variance weighted (IVW) approach. Additionally, sensitivity analyses were also conducted to validate the robustness of the causalty.

RESULTS

In the MR analyses, overall pneumonia demonstrated a suggestive but modest association with overall lung cancer risk (Odds ratio [OR]: 1.21, 95% confidence interval [CI]: 1.01 - 1.44, P = 0.037). The correlations between specific pneumonia types and overall lung cancer were not as significant, including bacterial pneumonia (OR: 1.07, 95% CI: 0.91 - 1.26, P = 0.386), viral pneumonia (OR: 1.00, 95% CI: 0.95 - 1.06, P = 0.891), asthma-related pneumonia (OR: 1.18, 95% CI: 0.92 - 1.52, P = 0.181), and COVID-19 (OR: 1.01, 95% CI: 0.78 - 1.30, P = 0.952). Reversely, with lung cancer as the exposure, we observed that overall lung cancer had statistically crucial associations with bacterial pneumonia (OR: 1.08, 95% CI: 1.03 - 1.13, P = 0.001) and viral pneumonia (OR: 1.09, 95% CI: 1.01 - 1.19, P = 0.037). Sensitivity analysis also confirmed the robustness of these findings.

CONCLUSION

This study has presented a systematic investigation into the causal relationships between pneumonia and lung cancer subtypes. Further prospective study is warranted to verify these findings.

Association of asthma and lung cancer risk: A pool of cohort studies and Mendelian randomization analysis

BACKGROUND

Over the past 2 decades, population-based studies have shown an increased association between asthma and the risk of lung cancer. However, the causal links between these 2 conditions remain poorly understood.

METHODS

We conducted a comprehensive search of various databases, including PubMed, Embase, Web of Science, and Cochrane Library, up until May 04, 2023. Only articles published in English were included in our study. We performed a meta-analysis using random-effects models to calculate the odds ratio (OR) and corresponding 95% confidence interval (CI). Subgroup analyses were conducted based on study design, gender, and histologic types. We also conducted a 2-sample Mendelian randomization (MR) using the genome-wide association study pooled data (408,422 people) published by the UK Biobank to explore further the potential causal relationship between asthma and lung cancer.

RESULTS

Our meta-analysis reviewed 24 population-based cohort studies involving 1072,502 patients, revealing that asthma is significantly associated with an increased risk of lung cancer (OR = 1.29, 95% CI 1.19-1.38) in all individuals. Subgroup analysis showed a significantly higher risk of lung cancer in females with asthma (OR = 1.23, 95% CI 1.01-1.49). We found no significant association between asthma and lung adenocarcinoma (LUAD) (OR = 0.76, 95% CI 0.54-1.05), lung squamous carcinomas (LUSC) (OR = 1.09, 95% CI 0.79-1.50), or small-cell lung cancer (SCLC) (OR = 1.00, 95% CI 0.68-1.49). Interestingly, our MR analysis supported an increasing causality between asthma and lung cancer (OR = 1.11, 95% CI 1.04-1.17, P = .0008), specifically in those who ever smoker (OR = 1.09, 95% CI 1.01-1.16, P = .0173) and LUSC pathological type (OR = 1.15, 95% CI 1.05-1.26, P = .0038).

CONCLUSION

Through meta-analysis, our study confirms that patients with asthma have a higher risk of developing lung cancer. Our MR study further support an increasing causal relationship between asthma and the risk of lung cancer, particularly in smokers and LUSC. Future studies examining the link between asthma and the risk of developing lung cancer should consider the bias of controlled and uncontrolled asthma.

Lung cancer risk score for ever and never smokers in China

BACKGROUND

Most lung cancer risk prediction models were developed in European and North-American cohorts of smokers aged ≥ 55 years, while less is known about risk profiles in Asia, especially for never smokers or individuals aged < 50 years. Hence, we aimed to develop and validate a lung cancer risk estimate tool for ever and never smokers across a wide age range.

METHODS

Based on the China Kadoorie Biobank cohort, we first systematically selected the predictors and explored the nonlinear association of predictors with lung cancer risk using restricted cubic splines. Then, we separately developed risk prediction models to construct a lung cancer risk score (LCRS) in 159,715 ever smokers and 336,526 never smokers. The LCRS was further validated in an independent cohort over a median follow-up of 13.6 years, consisting of 14,153 never smokers and 5,890 ever smokers.

RESULTS

A total of 13 and 9 routinely available predictors were identified for ever and never smokers, respectively. Of these predictors, cigarettes per day and quit years showed nonlinear associations with lung cancer risk (Pnon-linear < 0.001). The curve of lung cancer incidence increased rapidly above 20 cigarettes per day and then was relatively flat until approximately 30 cigarettes per day. We also observed that lung cancer risk declined sharply within the first 5 years of quitting, and then continued to decrease but at a slower rate in the subsequent years. The 6-year area under the receiver operating curve for the ever and never smokers' models were respectively 0.778 and 0.733 in the derivation cohort, and 0.774 and 0.759 in the validation cohort. In the validation cohort, the 10-year cumulative incidence of lung cancer was 0.39% and 2.57% for ever smokers with low (< 166.2) and intermediate-high LCRS (≥ 166.2), respectively. Never smokers with a high LCRS (≥ 21.2) had a higher 10-year cumulative incidence rate than those with a low LCRS (< 21.2; 1.05% vs. 0.22%). An online risk evaluation tool (LCKEY; http://ccra.njmu.edu.cn/lckey/web) was developed to facilitate the use of LCRS.

CONCLUSIONS

The LCRS can be an effective risk assessment tool designed for ever and never smokers aged 30 to 80 years.

Evaluation of the updated SOCcer v2 algorithm for coding free-text job descriptions in three epidemiologic studies

OBJECTIVES

Computer-assisted coding of job descriptions to standardized occupational classification codes facilitates evaluating occupational risk factors in epidemiologic studies by reducing the number of jobs needing expert coding. We evaluated the performance of the 2nd version of SOCcer, a computerized algorithm designed to code free-text job descriptions to US SOC-2010 system based on free-text job titles and work tasks, to evaluate its accuracy.

METHODS

SOCcer v2 was updated by expanding the training data to include jobs from several epidemiologic studies and revising the algorithm to account for nonlinearity and incorporate interactions. We evaluated the agreement between codes assigned by experts and the highest scoring code (a measure of confidence in the algorithm-predicted assignment) from SOCcer v1 and v2 in 14,714 jobs from three epidemiology studies. We also linked exposure estimates for 258 agents in the job-exposure matrix CANJEM to the expert and SOCcer v2-assigned codes and compared those estimates using kappa and intraclass correlation coefficients. Analyses were stratified by SOCcer score, score distance between the top two scoring codes from SOCcer, and features from CANJEM.

RESULTS

SOCcer's v2 agreement at the 6-digit level was 50%, compared to 44% in v1, and was similar for the three studies (38%-45%). Overall agreement for v2 at the 2-, 3-, and 5-digit was 73%, 63%, and 56%, respectively. For v2, median ICCs for the probability and intensity metrics were 0.67 (IQR 0.59-0.74) and 0.56 (IQR 0.50-0.60), respectively. The agreement between the expert and SOCcer assigned codes linearly increased with SOCcer score. The agreement also improved when the top two scoring codes had larger differences in score.

CONCLUSIONS

Overall agreement with SOCcer v2 applied to job descriptions from North American epidemiologic studies was similar to the agreement usually observed between two experts. SOCcer's score predicted agreement with experts and can be used to prioritize jobs for expert review.

Lung cancer occurrence after an episode of tuberculosis: a systematic review and meta-analysis

INTRODUCTION

People with tuberculosis experience long-term health effects beyond cure, including chronic respiratory diseases. We investigated whether tuberculosis is a risk factor for subsequent lung cancer.

METHODS

We searched PubMed, Scopus, Cochrane, Latin American and Caribbean Health Sciences Literature and the Scientific Electronic Library Online for cohort and case-control studies providing effect estimates for the association between tuberculosis and subsequent lung cancer. We pooled estimates through random-effects meta-analysis. The study was registered in PROSPERO (CDR42020178362).

RESULTS

Out of 6240 records, we included 29 cohort and 44 case-control studies. Pooled estimates adjusted for age and smoking (assessed quantitatively) were hazard ratio (HR) 1.51 (95% CI 1.30-1.76, I²=81%; five studies) and OR 1.74 (95% CI 1.42-2.13, I²=59%; 19 studies). The occurrence of lung cancer was increased for 2 years after tuberculosis diagnosis (HR 5.01, 95% CI 3.64-6.89; two studies), but decreased thereafter. Most studies were retrospective, had moderate to high risk of bias, and did not control for passive smoking, environmental exposure and socioeconomic status. Heterogeneity was high.

CONCLUSION

We document an association between tuberculosis and lung cancer occurrence, particularly in, but not limited to, the first 2 years after tuberculosis diagnosis. Some cancer cases may have been present at the time of tuberculosis diagnosis and therefore causality cannot be ascertained. Prospective studies controlling for key confounding factors are needed to identify which tuberculosis patients are at the highest risk, as well as cost-effective approaches to mitigate such risk.

Pulmonary Tuberculosis and Risk of Lung Cancer: A Systematic Review and Meta-Analysis

Pulmonary tuberculosis (TB) is a known risk factor for lung cancer. However, a detailed analysis of lung cancer type, age, sex, smoking, and TB burden associated with geographic and socioeconomic status has not been performed previously. We systematically appraised relevant observational studies reporting an association between pulmonary TB and lung cancer. All studies were included in the primary analysis, and studies that used robust TB diagnostic methods, such as validated medical diagnostic codes, were included in the secondary analysis. Thirty-two articles were included. The association between the history of pulmonary TB and diagnosis of lung cancer was statistically significant (OR 2.09, 95% CI: 1.62–2.69, p < 0.001). There was a high heterogeneity (I² = 95%), without any publication bias. The analysis indicated a high association in advanced articles describing stringent pulmonary TB diagnosis (OR 2.26, 95% CI: 1.29–3.94, p = 0.004). The subgroup analyses suggested a significant association in countries with medium or high TB burdens, from East Asia and the Pacific region, and upper-middle income countries. Heterogeneity within the subgroups remained high in a majority of the subgroup analyses. A meta-regression analysis revealed that younger patients showed a significantly higher association between TB and lung cancer (regression coefficient = 0.949, p < 0.001). The history of pulmonary TB is an independent risk factor for lung cancer, especially in younger patients diagnosed with pulmonary TB. Clinicians should be aware of this association while treating young patients with a history of pulmonary TB.

Impact of Variability in Job Coding on Reliability in Exposure Estimates Obtained via a Job-Exposure Matrix

OBJECTIVES

The use of a job-exposure matrix (JEM) to assess exposure to potential health hazards in occupational epidemiological studies requires coding each participant's job history to a standard occupation and/or industry classification system recognized by the JEM. The objectives of this study were to assess the impact of inter-coder variability in job coding on reliability in exposure estimates derived from linking the job codes to the Canadian job-exposure matrix (CANJEM) and to identify influent parameters.

METHOD

Two trained coders independently coded 1000 jobs sampled from a population-based case-control study to the ISCO-1968 occupation classification at the five-digit resolution level, of which 859 could be linked to CANJEM using both assigned codes. Each of the two sets of codes was separately linked to CANJEM and thereby generated, for each of the 258 occupational agents available in CANJEM, two exposure estimates: exposure status (yes/no) and intensity of exposure (low, medium, and high) for exposed jobs only. Then, inter-rater reliability (IRR) was computed (i) after stratifying agents in 4 classes depending, for each, on the proportion of occupation codes in CANJEM defined as 'exposed' and (ii) for two additional scenarios restricted to jobs coded differently: the first one using experts' codes, the other one using codes randomly selected. IRR was computed using Cohen's kappa, PABAK and Gwet's AC1 index for exposure status, and weighted kappa and Gwet's AC2 for exposure intensity.

RESULTS

Across all agents and based on all jobs, median (Q1, Q3; Nagents) values were 0.68 (0.59, 0.75; 220) for kappa, 0.99 (0.95, 1.00; 258) for PABAK, and 0.99 (0.97, 1.00; 258) for AC1. For the additional scenarios, median kappa was 0.28 (0.00, 0.45; 209) and -0.01 (-0.02, 00; 233) restricted to jobs coded differently using experts' and random codes, respectively. A similar decreasing pattern was observed for PABAK and AC1 albeit with higher absolute values. Median kappa remained stable across exposure prevalence classes but was more variable for low prevalent agents. PABAK and AC1 decreased with increasing prevalence. Considering exposure intensity and all exposed jobs, median values were 0.79 (0.68, 0.91; 96) for weighted kappa, and 0.95 (0.89, 0.99; 102) for AC2. For the additional scenarios, median kappa was, respectively, 0.28 (-0.04, 0.42) and -0.05 (-0.18, 0.09) restricted to jobs coded differently using experts' and random codes, with a similar though attenuated pattern for AC2.

CONCLUSION

Despite reassuring overall reliability results, our study clearly demonstrated the loss of information associated with jobs coded differently. Especially, in cases of low exposure prevalence, efforts should be made to reliably code potentially exposed jobs.

Previous pulmonary tuberculosis enhances the risk of lung cancer: systematic reviews and meta-analysis

PURPOSE

The possible association between history of pulmonary tuberculosis (TB) and lung cancer (LC) has attracted researchers' attention for several decades. This systematic review and meta-analysis aim to assess the association between previous pulmonary TB infection and LC risk.

METHODS

A Systematic and comprehensive search was performed in the following databases: PubMed, Embase, clinical key, Web of Science and Google Scholar, in articles and abstracts published from 1987 to 2021. Thirty-two articles (involving 50,290 cases and 846,666 controls) met the inconclusive criteria. The Comprehensive Meta-Analysis version 2.2 software was used for this meta-analysis.

RESULTS

The result of this meta-analysis demonstrates that pre-existing active pulmonary TB increases the risk of LC (RR = 2.170, 95% confidence interval [CI] 1.833-2.569, p < .001, I² = 91.234%). The results showed that the risk of the history of active pulmonary TB infection in adenocarcinoma was 2.605 (95% CI 1.706-3.979, p < .001, I² = 55.583%), in small-cell carcinoma was 2.118 (95% CI 1.544-2.905, p < .001, I² = 0.0%), in squamous-cell carcinoma, was 3.570 (95% CI 2.661 - 4.791, p < .001, I² = 42.695%) and 2.746 (95% CI 2.300-3.279, p < .001, I² = 41.686%) for other histological types of LCs. According to these results, a history of active pulmonary TB increases the risk of LC.

CONCLUSIONS

This study emphasizes the importance of LC screening in pulmonary TB patients even after the infection is treated. With the increased chances of LC in a patient who had a history of active pulmonary TB, there could be a need for a further follow-up period after pulmonary TB recovery.

Asthma severity as a contributing factor to cancer incidence: A cohort study

BACKGROUND

A putative link between asthma and asthma severity with the occurrence of cancer has been suggested but has not been fully investigated. The objective of this study is to assess the incidence of all types of cancer in a cohort of asthmatic patients.

METHODS AND FINDINGS

A single center cohort retrospective study was conducted to investigate the role of asthma as a potential risk factor for various cancers. Participants were followed for a period of 9 years from 01/01/2010 to 30/12/2018 and cancer incidence and its determinants were collected in asthmatic patients and controls from the same population source but without any respiratory disease. Overall, 2,027 asthma patients and 1,637 controls were followed up for an average of 9 years. The statistical analysis showed that 2% of asthma patients were diagnosed with various cancers, resulting in an incidence rate of cancer of 383.02 per 100,000 persons per year which is significantly higher than the 139.01 per 100,000 persons per year observed in matched controls (p-value < 0.001). The top four cancers reported among asthmatics were breast, colon, lung and prostate cancer. Lung cancer in asthmatics had the longest diagnosis period with a mean of 36.6 years compared to the shortest with prostate cancer with 16.5 years.

CONCLUSIONS

This study shows that asthma patients are at increased risk of different types of cancers with asthma severity and goiter as the main factors that may increase the risk of developing cancers among asthmatic patients.

The Incidence and Risk Analysis of Lung Cancer Development in Patients with Chronic Obstructive Pulmonary Disease: Possible Effectiveness of Annual CT-Screening

Purpose

Lung cancer is a serious complication in patients with chronic obstructive pulmonary disease (COPD) and accounts for approximately 15% of deaths in patients with COPD. However, with the exception of emphysema, few reports to date have been published on the factors that predict lung cancer development in COPD patients. It has been reported that patients with COPD develop lung cancer at a rate of 0.8% - 1.7%/year, but the incidence may be higher in the Japanese population. Therefore, we investigated the incidence of lung cancer and the lung cancer mortality rate in Japanese COPD patients, as well as factors that are associated with the development of lung cancer in COPD patients.

Patients and Methods

We followed up 224 patients with stable COPD and performed CT examinations at least once per year. The incidence of lung cancer was recorded and data at enrollment were compared with data of the group that did not develop lung cancer.

Results

Over a median follow-up period of 4.58 years, lung cancer was newly diagnosed in 19 patients; the incidence of lung cancer in this population was 1.85%/year. Patients who developed lung cancer had more severe emphysema assessed by CT and GOLD classification and were more likely to be current smokers than those who did not develop lung cancer. No other significant differences were observed between these two groups. Mortality was significantly increased in patients who developed lung cancer compared with those who did not.

Conclusion

In COPD patients, the incidence of lung cancer is higher and the development of lung cancer worsens the prognosis; however, lung cancer development is unpredictable and attention should be paid to all patients. Annual CT screening is important for early detection of lung cancer.

Acute exacerbations of COPD and risk of lung cancer in COPD patients with and without a history of asthma

Rationale

There is limited knowledge on the effect of acute exacerbations in chronic obstructive pulmonary disease (AECOPD) on lung cancer risk in COPD patients with and without a history of asthma. This study aims to examine whether AECOPD is associated with risk of lung cancer, and whether the effect depends on a history of asthma.

Methods

In the GenKOLS study of 2003–2005, 852 subjects with COPD performed spirometry, and filled out questionnaires on smoking habits, symptoms and disease history. These data were linked to lung cancer data from the Cancer Registry of Norway through 2013. AECOPD, measured at baseline was the main predictor. To quantify differences in lung cancer risk, we performed Cox-proportional hazards regression. We adjusted for sex, age, smoking variables, body mass index, and lung function.

Measurements and results

During follow-up, 8.8% of the subjects with, and 5.9% of the subjects without exacerbations were diagnosed with lung cancer. Cox regression showed a significant increased risk of lung cancer with one or more exacerbations in COPD patients without a history of asthma, HRR = 2.77 (95% CI 1.39–5.52). We found a significant interaction between a history of asthma and AECOPD on lung cancer.

Conclusions

AECOPD is associated with an increased risk of lung cancer in COPD patients without a history of asthma.

Development of a Coding and Crosswalk Tool for Occupations and Industries

Introduction

Job coding into a standard occupation or industry classification is commonly performed in occupational epidemiology and occupational health. Sometimes, it is necessary to code jobs into multiple classifications or to convert job codes from one classification to another. We developed a generic tool, called CAPS-Canada (http://www.caps-canada.ca/), that combines a computer-assisted coding tool covering seven International, Canadian and US occupation and industry classifications and an assistant facilitating crosswalks from one classification to another. The objectives of this paper are to present the different functions of the CAPS-Canada tool and to assess their contribution through an inter-rater reliability study.

Method

The crosswalk assistant was built based on a database of >30,000 jobs coded during a previous project. We evaluated to what extent it would allow automatic translation between pairs of classifications. The influence of CAPS-Canada on agreement between coders was assessed through an inter-rater reliability study comparing three approaches: manual coding, coding with CAPS-Canada without the crosswalk assistant, and coding with the complete tool. The material for this trial consisted of a random sample of 1000 jobs extracted from a case-control study and divided into three subgroups of equivalent size.

Results

Across the classification systems, the crosswalk assistant would provide useful information for 83-99% of jobs (median 95%) in a population similar to ours. Eighteen to eighty-one percent of jobs (median 56%) could be entirely automatically recoded. Based on our sample of 1000 jobs, inter-rater reliability in occupation coding ranged from 35.7 to 66.5% (median 53.7%) depending on the combination of classification/resolution. Compared with manual coding, the use of CAPS-Canada substantially improved inter-rater reliability.

Conclusion

CAPS-Canada is an attractive alternative to manual coding and is particularly relevant for coding a job into multiple classifications or for recoding jobs into other classifications.

Factors associated with lung cancer in COPD patients

Background

The risk of dying of lung cancer is up to eightfold higher in patients with COPD than in age- and gender-matched controls. The aim of this study was to investigate the factors associated with lung cancer in a large cohort of COPD patients from primary care centers.

Methods

To analyze whether age, gender, socioeconomic factors, comorbidity, and medication affect the risk of lung cancer in COPD, we used a COPD cohort of primary care patients. Data from primary care medical records and mandatory Swedish national registers were collected and linked in this population-based, retrospective observational registry study (NCT01146392).

Results

Of the total cohort, 19,894 patients were included in the study. Five hundred and ninety-four lung cancer cases were diagnosed, corresponding to 3.0% of the studied population. In a multivariate analysis, the risk of lung cancer was lower if the COPD patients had a concurrent asthma diagnosis (HR: 0.54, CI: 0.41–0.71), while the risk of lung cancer increased with increasing age. A decreased lung cancer risk was observed in an exposure-dependent manner in patients who were prescribed inhaled corticosteroids (HR: 0.52, CI: 0.37–0.73), while the opposite was found for the use of acetylsalicylic acid (HR: 1.58, CI: 1.15–2.16).

Conclusion

In this large population-based cohort, a concurrent asthma diagnosis and use of inhaled corticosteroids were independently related to decreased risk of lung cancer in COPD patients, while the use of acetylsalicylic acid was associated with an increased risk. The findings of the present study should be seen as hypothesis generating and need to be confirmed in prospective studies.

Associations between occupational exposure to benzene, toluene and xylene and risk of lung cancer in Montréal

BACKGROUND

Benzene, toluene and xylene (BTX) are aromatic hydrocarbons with inconclusive evidence of lung carcinogenicity. The aim of this research was to assess the associations between occupational exposures to BTX agents and lung cancer.

METHODS

In a population-based case-control study of lung cancer, occupational histories were obtained and exposures were assessed by experts. Unconditional multivariate logistic regression was used to estimate ORs and 95% CIs, among men, between various metrics of occupational exposure to BTX and lung cancer, while adjusting for established and possible risk factors.

RESULTS

Considerable overlap was found between occupational exposure to BTX, where the majority of exposed participants were exposed to all three chemicals. Lung cancer was associated with exposure to benzene (OR=1.35; 95% CI 0.99 to 1.84), toluene (OR=1.31; 95% CI 0.99 to 1.74) and xylene (OR=1.44; 95% CI 1.03 to 2.01). While these results were adjusted for smoking and other recognised and possible lung cancer risk factors, they were not mutually adjusted among the three BTX agents.

CONCLUSIONS

Our study provides suggestive evidence that occupational exposure to one or more of the BTX agents may be associated with lung cancer.

Associations between history of chronic lung disease and non-small cell lung carcinoma in Maryland: variations by sex and race

PURPOSE

Lung cancer is a multifactorial malignancy for which some risk factors, such as chronic lung diseases, their interactions with smoking, and how they differ by race and sex, are not fully understood. We investigated the associations between chronic inflammatory lung disease and non-small cell lung carcinoma (NSCLC) and how sex and race may affect such associations.

METHODS

Using logistic regression, we analyzed 1660 lung cancer cases and 1959 population controls and estimated adjusted odds ratios (AORs) and 95% confidence intervals (CIs).

RESULTS

Chronic lung disease was significantly associated with higher odds of having NSCLC in never (AOR = 1.99; 95% CI = 1.19-3.34), former (AOR = 1.68; 95% CI = 1.29-2.20), and current smokers (AOR = 2.40; 95% CI = 1.62-3.57), after adjustment for relevant covariates. For each 5-year increment in chronic lung disease duration, the risk of lung cancer increased only among females (AOR = 1.07; 95% CI = 1.02-1.13). Females, but not males, with asthma were at risk for NSCLC (AOR = 2.08; 95% CI = 1.40-3.10).

CONCLUSIONS

This study provides support for chronic lung inflammation as a potential contributing factor to lung cancer risk and possible sex difference in the inflammatory events underlying disease mechanisms.

Effect of pre existing respiratory conditions on survival of lung cancer patients: A nationwide population-based cohort study

BACKGROUND

Common diseases with potential to increase the risk of death from lung cancer have so far not been studied in large populations.

METHODS

We did a population-based retrospective cohort study using nationwide health insurance claims data from 2005 to 2012 in Korea including 205 403 lung cancer patients. Multivariate-adjusted hazard ratios (aHRs) of lung cancer mortality by presence, time intervals with lung cancer diagnosis and combinations of pre-existing chronic obstructive pulmonary disease (COPD), pneumonia, asthma and tuberculosis were calculated using the Cox-proportional hazards model.

RESULTS

The total number of person-years of follow-up was 397 780 and 60.2% of patients died (mean survival 23.2 months after lung cancer diagnosis). Lung cancer patients with previous respiratory disease had increased aHR for mortality (COPD, hazard ratio [HR] = 1.32, CI 1.29-1.35; pneumonia, HR = 1.14, CI 1.08-1.19; and asthma, HR = 1.11, CI 1.06-1.16). Risks were positively associated with longer duration of pre-existing disease diagnosis; cases with >5 years since diagnosis compared to <2 years: COPD, HR = 2.91, CI 2.82-3.00; pneumonia, HR = 1.67, CI 1.51-1.85; asthma, HR = 1.56, CI 1.45-1.68; and tuberculosis, HR = 2.03, CI 1.90-2.17. Furthermore, elevated HRs of death were found among patients with multiple pre-existing co-morbidities.

CONCLUSION

Hazards of death from lung cancer are significantly increased in cases with pre-existing lung disease, and worse with longer durations, and with multiple combinations before cancer diagnosis. Patients and physicians should be aware of these meaningful risk/prognostic factors for lung cancer when identifying high-risk patient groups.

Smoking exposure, loss of forced expiratory volume in one second and the risk of lung cancer among patients with malignant disease who present with cardiac or pulmonary symptoms: a cross-sectional study

BACKGROUND

Smokers with airway obstruction are at a higher risk of lung cancer than smokers without airway obstruction. Inflammation plays a key role in lung carcinogenesis. This single-center study prospectively assessed (i) the relationship between smoking exposure and the loss of forced expiratory volume in 1 s (FEV1) in determining lung cancer risk and (ii) the effect of lung cancer on systemic inflammation.

METHODS

The study group comprised 475 consecutively enrolled patients with cancer who presented with pulmonary or cardiac symptoms. The effects of smoking exposure and FEV1 loss on the predicted lung cancer risk were assessed using multiple logistic regression analysis. C-reactive protein (CRP) was used as a marker of inflammation.

RESULTS

The prevalence of lung cancer was 0.23. The lung cancer risk increased with the number of pack years and FEV1 loss (p < 0.01). Moving from the 5^th (-22% of the predicted value) to the 95^th percentile of FEV1 loss (56% of the predicted value) increased lung cancer risk from 0.07 to 0.23 (Δ = 0.16) at 0 pack years and from 0.39 to 0.73 (Δ = 0.34) at 70 pack years (95^th percentile). The values for Δ peaked at 61 pack years (0.34) and then decreased with a further increase in smoking exposure, without reaching the zero mark. Patients with lung cancer were more likely to have a CRP level above the median (4.05 mg/L) than patients with other cancers (adjusted odds ratio = 2.67).

CONCLUSIONS

Systemic inflammation is more pronounced in patients with lung cancer than in patients with other cancers. The effect of FEV1 loss on the patients' predicted risks of lung cancer increases with increasing smoking exposure. Measurements of FEV1 loss are useful to identify patients facing an increased risk of developing lung cancer.

Lung Malignancies in HIV Infection

Pulmonary malignancies are a major source of morbidity and mortality in HIV-infected persons. Non-AIDS-defining lung cancers (mostly non-small cell lung cancers) are now a leading cause of cancer death among HIV-infected persons. HIV-associated factors appear to affect the risk of lung cancer and may adversely impact cancer treatment and outcomes. HIV infection also may modify the potential harms and benefits of lung cancer screening with computed tomography. AIDS-defining lung malignancies include pulmonary Kaposi sarcoma and pulmonary lymphoma, both of which are less prevalent with widespread adoption of antiretroviral therapy.

Cumulative incidence of tuberculosis in lung cancer patients in Japan: A 6-year observational study

BACKGROUND

Tuberculosis (TB) remains a health-related problem worldwide, and certain malignancies are known to be associated with an increased risk of TB. Lung cancer is the leading cause of cancer-related death, and the number of patients with lung cancer has been reportedly increasing. As the prognosis of lung cancer remains poor, aggressive comprehensive therapies have been used. The immunosuppression caused by cancer itself and treatment-associated immune modulation may increase the risk of TB. The present study was conducted to investigate the cumulative incidence of TB in lung cancer patients.

METHODS

This observational study included 904 consecutive patients diagnosed with histologically confirmed lung cancer from March 2007 to March 2013 and followed until March 2015 (mean 25.2 months). The cumulative incidence of TB was estimated using the Kaplan-Meier method.

RESULTS

Nine lung cancer patients (1.00%) developed TB during the observation period. In all cases, TB occurred within 2 years of the diagnosis of lung cancer. The cumulative incidence of TB at 6 months, 1 year, and 2 years was 0.65%, 1.15%, and 1.38%, respectively.

CONCLUSIONS

The cumulative incidence of TB in lung cancer patients was 1.38% in Japan.

Lack of a protective effect of cotton dust on risk of lung cancer: evidence from two population-based case-control studies

BACKGROUND

Lung cancer is the leading cause of cancer death in North America. Exposure to cotton dust has previously been reported to decrease the risk of lung cancer.

METHODS

We used data from two large case-control studies conducted in Montreal from 1979-1986 (Study 1) and 1996-2002 (Study 2) respectively, to examine the association between occupational exposure to cotton dust and risk of lung cancer. Cases were diagnosed with incident histologically-confirmed lung cancer (857 in Study 1, 1203 in Study 2). Population controls were randomly selected from electoral lists and frequency-matched to cases by age and sex (533 in Study 1, 1513 in Study 2). Interviews for the two studies used a virtually identical questionnaire to obtain lifetime occupational and smoking history, and several lifestyle covariates. Each participant's lifetime occupational history was reviewed by experts to assess exposure to a number of occupational agents, including cotton dust. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by unconditional logistic regression, adjusting for potential confounders.

RESULTS

The lifetime prevalence of exposure to cotton dust was approximately 10%-15% in both studies combined, with some variation by study and by sex. Overall there was no decreased risk of lung cancer among subjects exposed to cotton dust. Rather, among all subjects there was a suggestion of slightly increased risk associated with any lifetime exposure to cotton dust (OR = 1.2, 95% CI: 1.0-1.5). This risk appeared to be concentrated among cases of adenocarcinoma (OR = 1.6, 95% CI: 1.2-2.2), and among moderate and heavy smokers (OR = 1.3, 95% CI: 1.0-1.7). There was no association when restricting to cases of either squamous cell or small cell cancer, or among never smokers and light smokers. An analogous examination of subjects exposed to wool dust revealed neither increased nor decreased risks of lung cancer.

CONCLUSIONS

There was no evidence that cotton dust exposure decreased risks of lung cancer.

Pneumonia and the incidence of cancer: a Danish nationwide cohort study

OBJECTIVES

To examine the risk of a subsequent pulmonary or extra-pulmonary cancer diagnosis following a first-time hospital-based diagnosis of pneumonia.

DESIGN

Population-based cohort study using Danish medical registries.

SETTING

All hospitals in Denmark.

SUBJECTS

A total of 342,609 patients with a first-time hospital-based (inpatient, emergency room or outpatient clinic) diagnosis of pneumonia between 1995 and 2011.

MAIN OUTCOME MEASURES

We quantified the excess risk of various cancers amongst pneumonia patients compared to the expected risk in the general population, using relative [standardised incidence ratios (SIRs)] and absolute risk calculations. Follow-up started 1 month after a hospital-based diagnosis of pneumonia and ended on 31 December 2011.

RESULTS

A total of 28,496 cancers were observed, compared with 21,625 expected, amongst 342,609 pneumonia patients followed for a median of 4.2 years. The absolute risk of a cancer diagnosis 1 to <6 months following a pneumonia diagnosis was 1.4%, with a corresponding SIR of 2.48 [95% confidence interval (CI) 2.41-2.55]. This was mainly due to an increased risk of lung cancer (eightfold) and haematological cancers (fourfold). The SIR for any cancer remained increased at 1.35 (95% CI 1.30-1.40) during 6-12 months of follow-up, and 1.20 (95% CI 1.18-1.22) during 1-5 years of follow-up. Beyond 5 years, an increased risk was maintained for lung, oesophageal, liver and bladder cancers, squamous cell carcinoma of the skin, lymphoma and multiple myeloma.

CONCLUSIONS

A hospital-based pneumonia diagnosis was associated with an increased risk of a cancer diagnosis, especially in the ensuing months, but the absolute risk was small.

Latent TB infection in newly diagnosed lung cancer patients - A multicenter prospective observational study

OBJECTIVES

Lung cancer and tuberculosis (TB) share common risk factors and are associated with high morbidity and mortality. Coexistence of lung cancer and TB were reported in previous studies, with uncertain pathogenesis. The association between lung cancer and latent TB infection (LTBI) remains to be explored.

METHODS

Newly diagnosed, treatment-naïve lung cancer patients were prospectively enrolled from four referral medical centers in Taiwan. The presence of LTBI was determined by QuantiFERON-TB Gold In-Tube (QFT-GIT). Demographic characteristics and cancer-related factors associated with LTBI were investigated. The survival status was also analyzed according to the status of LTBI.

RESULTS

A total of 340 lung cancer patients were enrolled, including 96 (28.2%) LTBI, 214 (62.9%) non-LTBI, and 30 (8.8%) QFT-GIT results-indeterminate cases. Non-adenocarcinoma cases had higher proportion of LTBI than those of adenocarcinoma, especially in patients with younger age. In multivariate analysis, COPD (OR 2.41, 95% CI 1.25-4.64), fibrocalcified lesions on chest radiogram (OR 2.73, 95% CI 1.45-5.11), and main tumor located in typical TB areas (OR 2.02, 95% CI 1.15-3.55) were independent clinical predictors for LTBI. Kaplan-Meier survival analysis demonstrated patients with indeterminate QFT-GIT results had significantly higher 1-year all-cause mortality than those with LTBI (p<0.001) and non-LTBI (p=0.003). In multivariate analysis, independent predictors for 1-year all-cause mortality included BMI<18.5 (HR 2.09, 95% CI 1.06-4.14, p=0.033), advanced stage of lung cancer (RR 7.76, 95% CI 1.90-31.78, p=0.004), and indeterminate QFT-GIT results (RR 2.40, 95% CI 1.27-4.54, p=0.007).

CONCLUSIONS

More than one-quarter of newly diagnosed lung cancer patients in Taiwan have LTBI. The independent predictors for LTBI include COPD, fibrocalcified lesions on chest radiogram, and main tumor located in typical TB areas. The survival rate is comparable between LTBI and non-LTBI cases. However, indeterminate QFT-GIT result was an independent predictor for all-cause mortality in lung cancer patients.

History of allergic diseases and lung cancer risk

BACKGROUND

The exact nature and direction of the association between a history of allergic diseases and lung cancer risk remain controversial.

OBJECTIVE

To examine the association between self-reported history of allergic diseases and lung cancer using data from a population-based case-control study conducted in the Montreal metropolitan area (1996-2002).

METHODS

The study is based on interview data collected from 1,169 incident lung cancer cases and 1,486 controls. Separate logistic regression models were used to estimate the relative risk of lung cancer, using odds ratios (ORs) and 95% confidence intervals (CIs), in subjects with vs without asthma, eczema, or hay fever after adjustment for several sociodemographic and lifestyle factors, including smoking.

RESULTS

For asthma, the OR was 0.90 (95% CI 0.65-1.24), which decreased to 0.76 (95% CI 0.54-1.08) for subjects whose onset was more than 2 years before lung cancer diagnosis or interview and then to 0.64 (95% CI 0.44-0.93) when restricted to subjects who reported using medication for their asthma. For eczema, the point estimate was 0.73 (95% CI 0.48-1.12), which decreased to 0.63 (95% CI 0.38-1.07) when considering eczema only in those who reported medication use. Hay fever showed the strongest inverse association with lung cancer (OR 0.37, 95% CI 0.24-0.59).

CONCLUSION

All 3 allergic diseases examined were inversely associated with lung cancer, although the strength of the protective effect varied. History of allergic diseases seems to have a protective role in lung cancer incidence, after consideration of potential confounders, including lifetime smoking history.

Increased lung cancer risk among patients with pneumococcal pneumonia: a nationwide population-based cohort study

BACKGROUND

The possible effects of pneumonia on subsequent lung cancer have been reported, but no relevant publications have focused on the association between pneumococcal pneumonia and lung cancer. The purpose of this study was to perform a nationwide population-based cohort study to investigate the risk of lung cancer after pneumococcus infection.

METHODS

This nationwide population-based cohort study was based on data obtained from the Taiwan National Health Insurance Database. In total, 22,034 pneumococcal pneumonia patients and 88,136 controls, matched for age and sex, were recruited for the study from 1997 to 2010.

RESULTS

The incidence rate of lung cancer (28.2 per 1,000 person-years) was significantly higher in pneumococcal pneumonia patients than in controls (8.7 per 1,000 person-years; incidence rate ratio, 3.25; 95 % confidence interval, 3.09-3.42; p < 0.001). Cox proportional hazards regression analysis showed a hazard ratio of 4.24 (95 % confidence interval, 3.96-4.55) for the pneumococcal pneumonia cohort after adjustment for age, gender, and comorbidities.

CONCLUSIONS

Pneumococcal pneumonia is associated with an increased risk of lung cancer. Thus, physicians should remain aware of this association when assessing patients with pneumococcal pneumonia.

How to measure hazards/risks following exposures to nanoscale or pigment-grade titanium dioxide particles

Due to its multifunctional applications, titanium dioxide particles have widespread use in commerce. The particle-types function as sources of pigment color, in food products, anti-bacterial components, ultraviolet radiation scavengers, catalysts, as well as in cosmetics. Because of its inherent properties in a diverse number of products, exposures may occur via any of the major point-of-entry routes, i.e., inhalation, oral or dermal. Although the majority of TiO2 applications are known to exist in the pigment-grade form, nanoscale forms of TiO2 are also common components in several products. This brief review is designed to identify relevant toxicology and risk-related issues which inform health effects assessments on the various forms of titanium dioxide particles. While there has been an abundance of hazard data generated on titanium dioxide particulates, many of the published reports have limited informational value for assessing health effects due, in large part, to shortcomings in experimental design issues, such as: (1) inadequate material characterization of test samples; (2) questionable relevance of experimental systems employed to simulate human exposures; (3) applications of generally high doses, exclusive focus on acute toxicity endpoints, and a lack of reference benchmark control materials, to afford interpretation of measured results; and/or (4) failure to recognize fundamental differences between hazard and risk concepts. Accordingly, a number of important toxicology issues are identified and integrated herein to provide a more comprehensive assessment of the health risks of different forms of pigment-grade and nanoscale titanium dioxide particles. It is important to note that particle-types of different TiO2 compositions may have variable toxicity potencies, depending upon crystal structure, particle size, particle surface characteristics and surface coatings. In order to develop a more robust health risk evaluation of TiO2 particle exposures, this review focuses on the following issues: (1) Introduction to TiO2 particle chemistry/functionality and importance of robust material characterization of test samples; (2) Implementation of meaningful hazard studies for gauging EHS safety issues – pulmonary bioassay data and development of the Nano Risk Framework for developmental nano TiO2 compounds; (3) Epidemiological study findings on titanium dioxide workers – the most heavily-exposed populations; (4) Methodologies for setting occupational exposure limits including benchmarking or bridging comparisons; and (5) The importance of particle overload data in the lungs of rats as it relates to gauging the relevance of health effects for humans. A comprehensive evaluation of the existing animal and human health data is a necessary prerequisite for facilitating accurate assessments of human health risks to TiO2 exposures.

Socioeconomic position and lung cancer risk: how important is the modeling of smoking?

BACKGROUND

Although it has been reported that low socioeconomic position (SEP) is associated with lung cancer, the extent to which this reflects SEP differences in cigarette smoking is unclear. We investigated how various modeling approaches for smoking might influence this observed association.

METHODS

We used data from a case-control study conducted in Montreal, Canada (1996-2002), comprising 1203 subjects with incident lung cancer and 1513 population controls. SEP was measured by census-based and self-reported income, residential value, education level, and occupational class. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression, and Akaike's Information Criterion (AIC) was used to compare model fit.

RESULTS

Associations were observed between SEP indicators and lung cancer, but gradually disappeared with more comprehensive adjustment for smoking. For comparisons of the highest to lowest categories of census-based income, the OR for lung cancer was 0.58 (95% CI = 0.32-1.05) when adjusting only for smoking status (never, former, current), but 0.97 (0.51-1.86) when adjusting for smoking status, cigarette-years, and time since cessation. For comparisons of highest to lowest levels of education, the ORs for lung cancer were 0.50 (0.38-0.65) and 0.76 (0.57-1.02), when making the least and most comprehensive adjustments for smoking, respectively. Similarly, comparing highly skilled with unskilled manual workers, the ORs were 0.78 (0.54-1.12) and 1.00 (0.68-1.47), respectively. With thorough smoking adjustment, associations between SEP indicators and lung cancer virtually disappeared, and SEP did not improve model fit.

CONCLUSIONS

Previously reported associations of SEP with lung cancer may be attributable to incomplete adjustment for smoking. Our findings underline the importance of adjusting for several dimensions of smoking behavior to make correct inferences.

Asthma and lung cancer risk: a systematic investigation by the International Lung Cancer Consortium

Asthma has been hypothesized to be associated with lung cancer (LC) risk. We conducted a pooled analysis of 16 studies in the International Lung Cancer Consortium (ILCCO) to quantitatively assess this association and compared the results with 36 previously published studies. In total, information from 585 444 individuals was used. Study-specific measures were combined using random effects models. A meta-regression and subgroup meta-analyses were performed to identify sources of heterogeneity. The overall LC relative risk (RR) associated with asthma was 1.28 [95% confidence intervals (CIs) = 1.16-1.41] but with large heterogeneity (I(2) = 73%, P < 0.001) between studies. Among ILCCO studies, an increased risk was found for squamous cell (RR = 1.69, 95%, CI = 1.26-2.26) and for small-cell carcinoma (RR = 1.71, 95% CI = 0.99-2.95) but was weaker for adenocarcinoma (RR = 1.09, 95% CI = 0.88-1.36). The increased LC risk was strongest in the 2 years after asthma diagnosis (RR = 2.13, 95% CI = 1.09-4.17) but subjects diagnosed with asthma over 10 years prior had no or little increased LC risk (RR = 1.10, 95% CI = 0.94-1.30). Because the increased incidence of LC was chiefly observed in small cell and squamous cell lung carcinomas, primarily within 2 years of asthma diagnosis and because the association was weak among never smokers, we conclude that the association may not reflect a causal effect of asthma on the risk of LC.

Asthma and risk of lung cancer

Asthma is a very common chronic disease that occurs in all age groups. Its high prevalence has significant health costs, which are even higher in the most severe disease forms. Lung cancer has the highest incidence of all cancers in the developed world and is an important cause of mortality. Patients with lung cancer are a big economic burden on health services, both in direct and indirect costs. Different authors suggest that atopic constitution, including different manifestations of allergy and asthma, are possible risk factors for lung cancer, above all in never-smokers. Given the high asthma prevalence and lung cancer incidence and mortality in developed countries, this association would have important public health implications. Uncertainties about the association and the underlying physiopathological mechanisms, however, seem to require further studies.

HIV infection in the etiology of lung cancer: confounding, causality, and consequences

Persons infected with HIV have an elevated risk of lung cancer, but whether the increase simply reflects a higher smoking prevalence continues to be debated. This review summarizes existing data on the association of HIV infection and lung cancer, with particular attention to study design and adjustment for cigarette smoking. Potential mechanisms by which HIV infection may lead to lung cancer are discussed. Finally, irrespective of causality and mechanisms, lung cancer represents an important and growing problem confronting HIV-infected patients and their providers. Substantial efforts are needed to promote smoking cessation and to control lung cancer among HIV-infected populations.

Increased lung cancer risk among patients with pulmonary tuberculosis: a population cohort study

INTRODUCTION

Given one third of the human population have been infected with tuberculosis, it is important to delineate the relationship between tuberculosis and lung cancer. This study explored whether contracting pulmonary tuberculosis is associated with an increased risk of developing lung cancers.

METHODS

In a cohort of 716,872 insured subjects, free from cancers, aged 20 years and older, 4480 patients with newly diagnosed tuberculosis were identified from the universal insurance claims in 1998-2000 and tracked until 2007 with the remaining insured without tuberculosis. We compared the incidence of lung cancers between the two cohorts and measured the associated hazard of developing lung cancer.

RESULTS

The incidence of lung cancers was approximately 11-fold higher in the cohort of patients with tuberculosis than nontuberculosis subjects (26.3 versus 2.41 per 10,000 person-years). Cox proportional hazard regression analysis showed a hazard ratio of 4.37 (95% confidence interval [CI]: 3.56-5.36) for the tuberculosis cohort after adjustment for the sociodemographic variables or 3.32 (95% CI: 2.70-4.09) after further adjustment for chronic obstructive pulmonary disease (COPD), smoking-related cancers (other than lung cancer), etc. The hazard ratio increased to 6.22 (95% CI: 4.87-7.94) with the combined effect with COPD or to 15.5 (95% CI: 2.17-110) with the combined effect with other smoking-related cancers.

CONCLUSIONS

This study provides a compelling evidence of increased lung cancer risk among individuals with tuberculosis. The risk may increase further with coexisting COPD or other smoking-related cancers.

Improving Detection Accuracy of Lung Cancer Serum Proteomic Profiling via Two-Stage Training Process

Background

Surface-Enhanced Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS) is a frequently used technique for cancer biomarker research. The specificity of biomarkers detected by SELDI can be influenced by concomitant inflammation. This study aimed to increase detection accuracy using a two-stage analysis process.

Methods

Sera from 118 lung cancer patients, 72 healthy individuals, and 31 patients with inflammatory disease were randomly divided into training and testing groups by 3:2 ratio. In the training group, the traditional method of using SELDI profile analysis to directly distinguish lung cancer patients from sera was used. The two-stage analysis of distinguishing the healthy people and non-healthy patients (1^st-stage) and then differentiating cancer patients from inflammatory disease patients (2^nd-stage) to minimize the influence of inflammation was validated in the test group.

Results

In the test group, the one-stage method had 87.2% sensitivity, 37.5% specificity, and 64.4% accuracy. The two-stage method had lower sensitivity (> 70.1%) but statistically higher specificity (80%) and accuracy (74.7%). The predominantly expressed protein peak at 11480 Da was the primary splitter regardless of one- or two-stage analysis. This peak was suspected to be SAA (Serum Amyloid A) due to the similar m/z countered around this area. This hypothesis was further tested using an SAA ELISA assay.

Conclusions

Inflammatory disease can severely interfere with the detection accuracy of SELDI profiles for lung cancer. Using a two-stage training process will improve the specificity and accuracy of detecting lung cancer.

Previous lung diseases and lung cancer risk: a systematic review and meta-analysis

BACKGROUND

In order to review the epidemiologic evidence concerning previous lung diseases as risk factors for lung cancer, a meta-analysis and systematic review was conducted.

METHODS

Relevant studies were identified through MEDLINE searches. Using random effects models, summary effects of specific previous conditions were evaluated separately and combined. Stratified analyses were conducted based on smoking status, gender, control sources and continent.

RESULTS

A previous history of COPD, chronic bronchitis or emphysema conferred relative risks (RR) of 2.22 (95% confidence interval (CI): 1.66, 2.97) (from 16 studies), 1.52 (95% CI: 1.25, 1.84) (from 23 studies) and 2.04 (95% CI: 1.72, 2.41) (from 20 studies), respectively, and for all these diseases combined 1.80 (95% CI: 1.60, 2.11) (from 39 studies). The RR of lung cancer for subjects with a previous history of pneumonia was 1.43 (95% CI: 1.22-1.68) (from 22 studies) and for subjects with a previous history of tuberculosis was 1.76 (95% CI=1.49, 2.08), (from 30 studies). Effects were attenuated when restricting analysis to never smokers only for COPD/emphysema/chronic bronchitis (RR=1.22, 0.97-1.53), however remained significant for pneumonia 1.36 (95% CI: 1.10, 1.69) (from 8 studies) and tuberculosis 1.90 (95% CI: 1.45, 2.50) (from 11 studies).

CONCLUSIONS

Previous lung diseases are associated with an increased risk of lung cancer with the evidence among never smokers supporting a direct relationship between previous lung diseases and lung cancer.

Prior lung disease and lung cancer risk in an occupational-based cohort in Yunnan, China

We used the data from a prospective cohort study among tin miners in Yunnan, China to investigate whether prior lung disease is a risk factor for lung cancer. Information on prior lung disease was obtained from baseline questionnaires. The Cox proportional hazards model was used to examine the relationship between prior lung disease and lung cancer risk. From 1992 to 2001, a total of 502 lung cancer cases were confirmed among 9295 cohort participants. Prior chronic bronchitis was associated with an increase in lung cancer risk with an adjusted HR of 1.50 (95% CI: 1.24-1.81). There was an increased risk of developing squamous cell carcinoma in the setting of prior chronic bronchitis and small cell carcinoma in association with asthma with an adjusted HRs of 1.57 (95% CI: 1.19-2.09) and 2.56 (95% CI: 1.38-4.75), respectively. This prospective study provides further evidence that prior chronic bronchitis correlates with increased lung cancer risk, especially for squamous cell carcinoma. Asthma is associated with increased risk of small cell lung carcinoma.

Nontypeable Haemophilus influenzae in chronic obstructive pulmonary disease and lung cancer

Chronic obstructive pulmonary disease (COPD) is predicted to become the third leading cause of death in the world by 2020. It is characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lungs to noxious particles and gases, most commonly cigarette smoke. Among smokers with COPD, even following withdrawal of cigarette smoke, inflammation persists and lung function continues to deteriorate. One possible explanation is that bacterial colonization of smoke-damaged airways, most commonly with nontypeable Haemophilus influenzae (NTHi), perpetuates airway injury and inflammation. Furthermore, COPD has also been identified as an independent risk factor for lung cancer irrespective of concomitant cigarette smoke exposure. In this article, we review the role of NTHi in airway inflammation that may lead to COPD progression and lung cancer promotion.

Interleukin 6, but not T helper 2 cytokines, promotes lung carcinogenesis

Several epidemiologic studies have found that smokers with chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lung, have an increased risk of lung cancer compared with smokers without COPD. We have shown a causal role for COPD-like airway inflammation in lung cancer promotion in the CCSP(Cre)/LSL-K-ras(G12D) mouse model (CC-LR). In contrast, existing epidemiologic data do not suggest any definite association between allergic airway inflammation and lung cancer. To test this, CC-LR mice were sensitized to ovalbumin (OVA) and then challenged with an OVA aerosol weekly for 8 weeks. This resulted in eosinophilic lung inflammation associated with increased levels of T helper 2 cytokines and mucous metaplasia of airway epithelium, similar to what is seen in asthmatic patients. However, this type of inflammation did not result in a significant difference in lung surface tumor number (49 ± 9 in OVA vs. 52 ± 5 in control) in contrast to a 3.2-fold increase with COPD-like inflammation. Gene expression analysis of nontypeable Haemophilus influenzae (NTHi)-treated lungs showed upregulation of a different profile of inflammatory genes, including interleukin 6 (IL-6), compared with OVA-treated lungs. Therefore, to determine the causal role of cytokines that mediate COPD-like inflammation in lung carcinogenesis, we genetically ablated IL-6 in CC-LR mice. This not only inhibited intrinsic lung cancer development (1.7-fold) but also inhibited the promoting effect of extrinsic COPD-like airway inflammation (2.6-fold). We conclude that there is a clear specificity for the nature of inflammation in lung cancer promotion, and IL-6 has an essential role in lung cancer promotion.

Pulmonary infections and risk of lung cancer among persons with AIDS

Lung cancer risk is significantly increased among persons with AIDS (PWA), and increased smoking may not explain all of the elevated risk, suggesting a role for additional cofactors. We investigated whether AIDS-defining pulmonary infections (recurrent pneumonia, Pneumocystis jirovecii pneumonia, and pulmonary tuberculosis) affected the risk of subsequent lung cancer over 10 years after AIDS onset among 322,675 PWA, whose records were linked with cancer registries in 11 US regions. We assessed lung cancer hazard ratios (HRs) using Cox regression and indirectly adjusted HRs for confounding by smoking. Individuals with recurrent pneumonia (n = 5317) were at significantly higher lung cancer risk than those without [HR = 1.63, 95% confidence interval (CI) = 1.08 to 2.46, adjusted for age, race, sex, HIV acquisition mode, CD4 count, and AIDS diagnosis year]. This association was especially strong among young PWA (<50 years HR = 1.99 vs. ≥50 years HR = 1.10) and was significantly elevated during 5-10 years after recurrent pneumonia diagnosis (HR = 2.41; 95% CI = 1.07 to 5.47). Although attenuated, HRs for recurrent pneumonia remained nonsignificantly elevated after indirect adjustment for smoking. Lung cancer risk was unrelated to tuberculosis [(n = 13,878) HR = 1.12, 95% CI = 0.82 to 1.53] or Pneumocystis jirovecii pneumonia [(n = 69,771) HR = 0.97, 95% CI = 0.80 to 1.18]. The increased lung cancer risk associated with recurrent pneumonia supports the hypothesis that chronic pulmonary inflammation arising from infections contributes to lung carcinogenesis.

Pulmonary tuberculosis increases the risk of lung cancer: a population-based cohort study

BACKGROUND

The possible effect of pulmonary tuberculosis (TB) on subsequent lung cancer development has been suspected, but the evidence remains inconsistent. The purpose of this study was to perform a nationwide population-based cohort study to investigate the risk of lung cancer after pulmonary TB infection.

METHODS

This nationwide population-based cohort study was based on data obtained from the Taiwan National Health Insurance Database. In total, 5657 TB patients and 23,984 controls matched for age and sex were recruited for the study from 1997 to 2008.

RESULTS

The incidence rate of lung cancer (269 of 100,000 person-years) was significantly higher in the pulmonary TB patients than that in controls (153 of 100,000 person-years) (incidence rate ratio [IRR], 1.76; 95% confidence interval [CI], 1.33-2.32; P < .001). Compared with the controls, the IRRs of lung cancer in the TB cohort were 1.98 at 2 to 4 years, 1.42 at 5 to 7 years, and 1.59 at 8 to 12 years after TB infections. The multivariate Cox proportional hazards model revealed pulmonary TB infections (hazard ratio [HR], 1.64; 95% CI, 1.24-2.15; P < .001) and chronic obstructive pulmonary disease (HR, 1.09; 95% CI, 1.03-1.14; P = .002) to be independent risk factors for lung cancer.

CONCLUSIONS

Pulmonary infection with TB is associated with an increased risk of lung cancer.

History of asthma or eczema and cancer risk among men: a population-based case-control study in Montreal, Quebec, Canada

BACKGROUND

Epidemiologic evidence regarding the association between a history of allergic diseases and different cancer types has been inconsistent.

OBJECTIVE

To examine whether a history of asthma or eczema is associated with various cancers among Canadian men in a population based case-control study conducted in the 1980s.

METHODS

Questionnaire-based interviews were performed by a team of trained interviewers from August 1979 to March 1986. Information collected included self-reported history of a prior medical diagnosis of asthma and of eczema, medication use, and several covariates among 3,300 cancer cases and 512 population controls. Logistic regression models were used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association between asthma or eczema and more than 20 cancer types combined, as well as for each of the 8 most common cancer types (stomach, colon, rectum, lung, prostate, bladder, skin, and lymph nodes).

RESULTS

Considering study participants who reported a prior medical diagnosis of the disease and medication use, a history of asthma was negatively associated with all cancer types combined (OR, 0.72; 95% CI, 0.5-1.1) and similarly for a history of eczema (OR, 0.66; 95% CI, 0.4-1.1). Although ORs between asthma and eczema and most individual types were below 1.0, only 2 ORs were significantly below 1.0: that between asthma and stomach cancer (OR, 0.27; 95% CI, 0.1-0.9) and that between eczema and lung cancer (OR, 0.34; 95% CI, 0.2-0.7).

CONCLUSION

Allergic conditions that result from a hyperreactive immune system might lead to a more efficient elimination of abnormal cells, thus lowering cancer risks.

Lung cancer risk in never-smokers: a population-based case-control study of epidemiologic risk factors

BACKGROUND

We conducted a case-control study in the greater Toronto area to evaluate potential lung cancer risk factors including environmental tobacco smoke (ETS) exposure, family history of cancer, indoor air pollution, workplace exposures and history of previous respiratory diseases with special consideration given to never smokers.

METHODS

445 cases (35% of which were never smokers oversampled by design) between the ages of 20-84 were identified through four major tertiary care hospitals in metropolitan Toronto between 1997 and 2002 and were frequency matched on sex and ethnicity with 425 population controls and 523 hospital controls. Unconditional logistic regression models were used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI) for the associations between exposures and lung cancer risk.

RESULTS

Any previous exposure to occupational exposures (OR total population 1.6, 95% CI 1.4-2.1, OR never smokers 2.1, 95% CI 1.3-3.3), a previous diagnosis of emphysema in the total population (OR 4.8, 95% CI 2.0-11.1) or a first degree family member with a previous cancer diagnosis before age 50 among never smokers (OR 1.8, 95% CI 1.0-3.2) were associated with increased lung cancer risk.

CONCLUSIONS

Occupational exposures and family history of cancer with young onset were important risk factors among never smokers.

Occupational exposure to silica and lung cancer: pooled analysis of two case-control studies in Montreal, Canada

BACKGROUND

Respirable crystalline silica is a highly prevalent occupational exposure and a recognized lung carcinogen. Most previous studies have focused on selected high-exposure occupational groups. This study examines the relationship between occupational exposure to silica and lung cancer in an occupationally diverse male population.

METHODS

Two large population-based case-control studies of lung cancer were conducted in Montreal, one in 1979-1986 (857 cases, 533 population controls, 1,349 cancer controls) and the second in 1996-2001 (738 cases and 899 controls). Interviews provided descriptive lifetime job histories, smoking histories, and other information. Industrial hygienists translated job histories into histories of exposure to a host of occupational substances, including silica. Relative risk was estimated, adjusting for several potential confounders, including smoking.

RESULTS

The odds ratio for substantial exposure to silica was 1.67 (95% confidence interval, 1.21-2.31) and for any exposure was 1.31 (95% confidence interval, 1.08-1.59). Joint effects between silica and smoking were between additive and multiplicative, perhaps closer to the latter. In this population, it is estimated that approximately 3% of lung cancers were attributable to substantial silica exposure.

CONCLUSIONS

The carcinogenicity of inhaled crystalline silica was observed in a population with a wide variety of exposure circumstances.

IMPACT

The finding of carcinogenicity across a wide range of occupations complements prior studies of specific high-exposure occupations. This suggests that the burden of cancer induced by silica may be much greater than previously thought.

Lung cancer risk associated with occupational exposure to nickel, chromium VI, and cadmium in two population-based case-control studies in Montreal

BACKGROUND

Nickel, chromium VI, and cadmium have been identified as lung carcinogens in highly exposed cohorts. The purpose of this study was to examine the etiological link between lung cancer and these metals in occupations, that usually entail lower levels of exposure than those seen in historical cohorts.

METHODS

Two population-based case-control studies were conducted in Montreal, from 1979 to 1986 and from 1996 to 2001, comprising 1,598 cases and 1,965 controls. A detailed job history was obtained to evaluate lifetime occupational exposure to many agents, including nickel, chromium VI, and cadmium compounds.

RESULTS

Lung cancer odds ratios were increased only among former or non-smokers: 2.5 (95% CI: 1.3-4.7) for nickel exposure, 2.4 (95% CI: 1.2-4.8) for chromium VI, and 4.7 (95% CI: 1.5-14.3) for cadmium. The metals did not increase risk among smokers.

CONCLUSIONS

While excess risks due to these metal compounds were barely discernable among smokers, carcinogenic effects were seen among non-smokers.

Risk of lung cancer following nonmalignant respiratory conditions among nonsmoking women living in Shenyang, Northeast China

BACKGROUND

There has been conflicting evidence about possible associations between nonmalignant respiratory conditions (NMRCs) and subsequent risk of lung cancer. Determination of whether or not there is such an association has potential importance for managing NMRCs, for screening of lung cancer, and for understanding mechanisms of carcinogenesis.

METHODS

A hospital-based, case-control study involving interviews with 226 female nonsmoking lung cancer patients and 279 matching population controls was conducted in Shenyang, Northeast China, between January 2004 and December 2007. A standardized interview collected information on a variety of potential risk factors, including a history of physician-diagnosed NMRCs (pulmonary tuberculosis, chronic bronchitis, emphysema, asthma, and bronchiectasis), and age/year in which each condition was first diagnosed. Multivariate logistic regression analyses were applied to assess the associations between NMRCs and subsequent lung cancer risk.

RESULTS

Compared with those without, subjects with a history of NMRC experience greater risk of lung cancer (OR=2.0, 95% CI 1.2-3.4), particularly following a diagnosis of pulmonary tuberculosis (OR=4.7, 95% CI 1.6-13.2). The results from subgroup analysis, when limited to small cell lung cancer, showed a 6.2-fold increase in lung cancer risk among asthmatics (95% CI 1.5-25.8). However, there was no evidence of a significant association between chronic bronchitis and lung cancer.

CONCLUSIONS

This study strengthens the evidence linking NMRCs, especially pulmonary tuberculosis, to lung cancer even in lifelong nonsmoking women.

Antigen specificity determines the pro- or antitumoral nature of CD8+ T cells

Although CD8+ T cells are usually considered antitumoral, several recent studies report that the cells can also promote tumor progression. Using the melanoma cell line B16 as a murine model of pulmonary metastasis, we examined whether the pro- versus antitumoral effects of CD8+ T cells relate to their Ag specificity. Results of the study indicate that although CD8+ T cells specific for tumor Ags promote tumor rejection, CD8+ T cells specific for unrelated Ags promote tumor progression. We found the effect to be partly attributable to CD8+ T cells dampening effective antitumor NK cell responses. Notably, activation of CD8+ T cell responses by an unrelated stimulus, in this case infection with influenza virus, increased the number of pulmonary tumor nodules. These data provide a rationale for previously unexplained data identifying contrasting roles for CD8+ T cells in tumor progression.

Facts and fiction of the relationship between preexisting tuberculosis and lung cancer risk: a systematic review

There has been conflicting evidence concerning the possible association between tuberculosis (TB) and subsequent risk of lung cancer. To investigate whether currently published epidemiological studies can clarify this association, we performed a systematic review of 37 case-control and 4 cohort studies (published between January 1966 and January 2009) and a meta-analysis of risk estimates, with particular attention to the role of smoking, passive smoking and the timing of diagnosis of TB on this relationship. Data for the review show a significantly increased lung cancer risk associated with preexisting TB. Importantly, the association was not due to confounding by the effects of tobacco use (RR=1.8, 95% confidence interval (CI)=1.4-2.2, among never smoking individuals), lifetime environmental tobacco smoke exposure (RR=2.9, 95%CI=1.6-5.3, after controlling) or the timing of diagnosis of TB (the increased lung cancer risk remained 2-fold elevated for more than 20 years after TB diagnosis). Interestingly, the association was significant with adenocarcinoma (RR=1.6, 95%CI=1.2-2.1), but no significant associations with squamous and small cell type of lung cancer were observed. Although no causal mechanism has been demonstrated for such an association, present study supports a direct relation between TB and lung cancer, especially adenocarcinomas.