Worldwide epidemiological patterns of lung cancer in nonsmokers

Disparities in clinical and demographic characteristics among Asian/Pacific Islander and Non-Hispanic White newly diagnosed lung cancer patients

PURPOSE

Racial disparities persist among lung cancer patients but have not been adequately studied among Asian/Pacific Islander (API) subgroups, which are heterogeneous. This study compared clinical and demographic characteristics at diagnosis of API subgroups and NHW patients.

METHODS

NHW and API adults diagnosed with lung cancer were identified from the Surveillance, Epidemiology, and End Results database (1990-2015). API was divided into eight subgroups: Chinese, Japanese, Filipino, Hawaiian/Pacific Islander, Korean, Vietnamese, Asian Indian/Pakistani, and Other. Multivariable multinomial logistic regression models were used to assess adjusted associations of clinical and demographic factors with API/subgroups.

RESULTS

There were 522,702 (92.6%) NHW and 41,479 (7.4%) API lung cancer patients. API were less likely to be diagnosed at the age of ≥ 80 years (OR_adj 0.53, 95% CI 0.48-0.58 for ≥ 80 vs. ≤ 39 years) than NHW. However, Japanese patients were more often diagnosed at ≥ 80 years compared to other ethnic subgroups. API were less often female (OR_adj 0.85, 95% CI 0.83-0.86), and unmarried (OR_adj 0.71, 95% CI 0.68-0.74); however, among API, Japanese, Hawaiian/Pacific Islander, Korean, and Vietnamese were more often unmarried, compared to Chinese patients. API were more frequently diagnosed at stage IV, compared to stage I (OR_adj 1.31, 95% CI 1.27-1.35). API had significantly less squamous cell carcinoma (OR_adj 0.54, 95% CI 0.52-0.56, compared to adenocarcinoma); among API, Japanese, Filipino, Hawaiian/Pacific Islander, Korean, Asian Indian/Pakistani, and Other were more likely than Chinese patients to present with squamous cell histology (range: OR_adj[Other] 1.24, 95% CI 1.09-1.41; OR_adj[Hawaiian/Pacific Islander] 2.47, 95% CI 2.22-2.75).

CONCLUSION

At diagnosis, there are significant differences in demographic and clinical characteristics between NHW, API, and API subgroups. Treating API patients as a single population may overlook biological, environmental, and behavioral differences that might be beneficial in designing prevention strategies and treatment.

Molecular profiling and characteristics of non-small-cell lung cancer patients in Georgia

Aims: In patients with advanced non-small-cell lung cancer, the correlation between histopathology, smoking status, driver oncogene mutations and PD-L1 overexpression were investigated. Patients and methods: A total of 202 patients were identified. Research was done in Georgia. Results: EGFR mutations were detected in 6% of the tested cases (12/187) and five out of 12 EGFR+ cases had histology consistent with squamous cell carcinoma. No statistically significant correlation was observed between PD-L1 expression, smoking status and clinicopathological characteristics. However, the correlation between smoking status and histology was statistically significant (p = 0.0264), as never-smokers had a higher incidence of adenocarcinoma histology. Conclusion: The study showed a small percentage of EGFR mutations associated with adenocarcinoma histology and revealed a solid existence of this mutation in squamous cell carcinoma histology. A higher incidence of adenocarcinoma histology was observed in never-smokers.

Risk of lung cancer among women in relation to lifetime history of tobacco smoking: a population-based case-control study in France (the WELCA study)

Background

This study aims to provide new insights on the role of smoking patterns and cigarette dependence in female lung cancer, and to examine differences by histological subtype.

Methods

We conducted a population-based case-control study in the great Paris area among women including 716 incident cases diagnosed between 2014 and 2017 and 757 age-matched controls. Detailed data on smoking history was collected during in-person interviews to assess intensity and duration of tobacco smoking, time since cessation, smoking habits (depth of smoke inhalation, use of filter, type of tobacco, and type of cigarettes) and Fagerström test for cigarette dependence. The comprehensive smoking index (CSI), a score modelling the combined effects of intensity, duration and time since quitting smoking was determined for each subject. Multivariable logistic regression models were fitted to calculate odds ratios (ORs) and their confidence intervals (95%CI) of lung cancer associated with smoking variables.

Results

Lung cancer risk increased linearly with intensity and duration of tobacco smoking while it decreased with time since cessation, to reach the risk in never-smokers after 20 years of abstinence. The combined effect of intensity and duration of tobacco smoking was more than multiplicative (p-interaction 0.012). The OR in the highest vs the lowest quartile of CSI was 12.64 (95%CI 8.50; 18.80) (p-trend < 0.001). The risk of small cell or squamous cell carcinomas increased with the CSI more sharply than the risk of adenocarcinomas. Deep smoke inhalation, dark vs blond tobacco, conventional vs light cigarettes, and unfiltered vs filtered cigarettes, as well as having mixed smoking habits, were found to be independent risk factors. Having high cigarette addiction behaviours also increased the risk after adjusting for CSI.

Conclusion

This study provides additional insights on the effects of tobacco smoking patterns on lung cancer risk among women.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08433-z.

Personalising lung cancer screening: An overview of risk-stratification opportunities and challenges

Randomised clinical trials have shown the efficacy of computed tomography lung cancer screening, initiating discussions on whether and how to implement population‐based screening programs. Due to smoking behaviour being the primary risk‐factor for lung cancer and part of the criteria for determining screening eligibility, lung cancer screening is inherently risk‐based. In fact, the selection of high‐risk individuals has been shown to be essential in implementing lung cancer screening in a cost‐effective manner. Furthermore, studies have shown that further risk‐stratification may improve screening efficiency, allow personalisation of the screening interval and reduce health disparities. However, implementing risk‐based lung cancer screening programs also requires overcoming a number of challenges. There are indications that risk‐based approaches can negatively influence the trade‐off between individual benefits and harms if not applied thoughtfully. Large‐scale implementation of targeted, risk‐based screening programs has been limited thus far. Consequently, questions remain on how to efficiently identify and invite high‐risk individuals from the general population. Finally, while risk‐based approaches may increase screening program efficiency, efficiency should be balanced with the overall impact of the screening program. In this review, we will address the opportunities and challenges in applying risk‐stratification in different aspects of lung cancer screening programs, as well as the balance between screening program efficiency and impact.

Lung cancer screening strategy for non-high-risk individuals: a narrative review

Lung cancer is the deadliest malignancy worldwide, accounting for almost 20% of all cancer deaths. Clinical trials, such as NLST and NELSON, have proved the survival benefit of lung cancer screening using low-dose computed tomography (LDCT), and most of the lung cancer screening guidelines recommended annual lung cancer screening by LDCT for high-risk individuals. However, a relatively high proportion of lung cancer patients do not have risk factors, and it is questionable whether non-high-risk individuals should receive LDCT screening. In this review, we reviewed risk factors of lung cancer and summarized the benefits and potential harms of LDCT screening. After clarifying the differences between China and western countries in lung cancer screening, we recommended that non-high-risk individuals should receive LDCT screening with an interval of five to ten years. To better balance benefits and harms from LDCT screening, we also proposed a flexible screening strategy using LDCT based on lung cancer risk. Hopefully, it may help reduce unnecessary radiation exposure from CT scans while decreasing mortality of lung cancer.

Smoking Status Among Patients With Newly Diagnosed Lung Cancer in Taiwan

Background

Continued smoking after receiving a diagnosis of cancer seriously affects disease prognosis and survival. The prevalence and risk factors of continued smoking among patients with newly diagnosed lung cancer are unknown in Taiwan.

Purpose

The aims of this study were to assess the smoking status of patients with newly diagnosed lung cancer and to identify the characteristics that are associated with different smoking statuses.

Methods

Baseline data of a longitudinal study on smoking behaviors after lung cancer diagnosis were analyzed in this study. Patients were consecutively recruited from three medical centers in northern Taiwan. A structured questionnaire and medical chart reviews were used to collect data. Multinomial logistic regression analysis was used to examine the factors associated with continuing to smoke after being diagnosed with lung cancer.

Results

Among the 406 patients with newly diagnosed lung cancer who were recruited, 47.0% were never-smokers and 53.0% were ever-smokers. Among the second group, 38% were former smokers, 18% were recent quitters, and 44% were current smokers. Compared with former smokers, current smokers were more likely to be younger (OR = 1.05), to not exercise regularly (OR = 2.74), to currently live with smokers (OR = 2.48), and to have lower self-efficacy for refusing to smoke (OR = 0.95). Compared with recent quitters, current smokers were more likely to have lower self-efficacy for refusing to smoke.

Conclusions/Implications for Practice

A significant proportion of ever-smoker lung cancer patients in Taiwan will continue to smoke after receiving their diagnosis. Variables known to modify the risk factors associated with continued smoking such as regular exercise and better refusal self-efficacy should be considered and incorporated into future smoking cessation programs for patients with lung cancer.

Non-Smoking-Associated Lung Cancer: A distinct Entity in Terms of Tumor Biology, Patient Characteristics and Impact of Hereditary Cancer Predisposition

Non-small cell lung cancer (NSCLC) in non-, and especially in never-smoking patients is considered a biologically unique type of lung cancer, since risk factors and tumorigenic conditions, other than tobacco smoke, come into play. In this review article, we comprehensively searched and summarized the current literature with the aim to outline what exactly triggers lung cancer in non-smokers. Changes in the tumor microenvironment, distinct driver genes and genetic pathway alterations that are specific for non-smoking patients, as well as lifestyle-related risk factors apart from tobacco smoke are critically discussed. The data we have reviewed highlights once again the importance of personalized cancer therapy, i.e., careful molecular and genetic assessment of the tumor to provide tailored treatment options with optimum chances of good response-especially for the subgroups of never-smokers.

The cytokinesis-blocked micronucleus assay as a novel biomarker for selection of lung cancer screening participants

Background

Despite the promising results of the National Lung Screening Trial in reducing lung cancer mortality among high risk smokers, several challenges remain to be addressed. These include the high false positive rates and the large number of smokers screened in order to prevent one lung cancer death. In addition, host genetic susceptibility has not been integrated into selection of who should be screened. These challenges highlight the need to develop robust ways to identify susceptible smokers for appropriate screening.

Methods

We used the cytokinesis block micronucleus (CBMN) assay to assess smoking induced genetic instability among NLST participants. Blood cultures were prepared at time of entry into the screening study and DNA damage was recorded as the frequency of binucleated nucleoplasmic bridges and micronuclei. Low dose CT (LDCT) and chest X-ray (CXR) image findings were available upon unblinding of the NLST study and imaging data were merged with blood marker data for statistical analysis.

Results

A total of 641 participants were included in this study. The frequency of the CBMN endpoints at time of entry into the study was significantly higher among study participants who had a positive finding during the 3-year screening or reported lung cancer at the end of the follow-up period as compared to participants who were negative. Growth curve models were used to compare trajectories of change in CBMN endpoints between entry into the study and end-of-screening period. A statistically significant increase was predicted for CBMN endpoints among the study participants who were positive versus those who remained negative at the end-of-screening period (P<0.001).

Conclusions

Genetic instability biomarkers have the potential of facilitating the identification of genetically susceptible high-risk smokers who would benefit from targeted lung screening programs.

Lung cancer in never smokers from the Princess Margaret Cancer Centre

Introduction

Lung cancer in never smokers represents a distinct epidemiological, clinical, and molecular entity.

Results

Most 712 never smoking lung cancer patients were female (72%) with a median age at diagnosis of 62.2 years (18–94). Caucasians (46%), East Asians (42%), adenocarcinoma histology (87%) and presentation with metastatic disease at diagnosis (59%) were common. Of 515 patients with available archival tissue, the most common identified single mutations were EGFR (52.2%), followed by ALK (7.5%), KRAS (2.3%), TP53 (1.3%), ERBB2 (1%), BRAF (0.4%), PIK3CA (0.4%), SMAD4 (0.4%), CTNNB1 (0.2%), AKT1 (0.2%), and NRAS (0.2%); 8% tumors had multiple mutations, while 25.8% had none identified. Median overall survival (mOS) was 42.2 months (mo) for the entire cohort. Patients with mutations in their tumors had significantly better mOS (69.5 mo) when compared to those without (31.0 mo) (HR = 0.59; 95% CI: 0.44–0.79; p < 0.001). Earlier stage (p < 0.001), adenocarcinoma histology (p = 0.012), good performance status (p < 0.001) and use of targeted therapy (p < 0.001) were each independently associated with longer survival. Patients with ALK-translocation-positive tumours have significantly longer OS compared to those without any mutations (p = 0.0029) and to those with other and null mutations (p = 0.022).

Conclusions

Lung cancer in never smokers represents a distinct clinical and molecular entity characterized by a high incidence of targetable mutations and long survival.

Methods

We analyzed retrospectively the data from electronic patient records of never smokers diagnosed with lung cancer treated at the Princess Margaret Cancer Centre (Toronto) between 1988–2015 to characterize demographic and clinical features, pathology, molecular profile (using hotspot or targeted sequencing panels), treatment and survival.

Metastatic nonsmall cell lung cancer in South India: A regional demographic study

BACKGROUND

Nonsmall cell lung cancer (NSCLC) has varying epidemiological patterns in different countries and also in different regions of each country. In a country with a high prevalence of lung cancer such as India, regional variations in demography exist.

AIM

A study of unique demographic trends of metastatic NSCLC patients presenting to our regional cancer center.

MATERIALS AND METHODS

We did a retrospective analysis of histologically confirmed metastatic NSCLC patients who presented to our Department of Medical Oncology between August 2012 and July 2014.

RESULTS

A total of 304 patients were analyzed. About 55.6% of the patients were in the age group of 41-60 years. About 79.6% of the patients were symptomatic for <6 months before presentation. About 63.5% of the patients were smokers presenting with a median age of 59 years whereas nonsmokers formed 36.51% of the patients presenting with a median age of 47 (P < 0.001). About 82.6% of the male patients and 4.1% of female patients were smokers. Equal number of all patients had adenocarcinoma (AC) and squamous cell carcinoma (SCC) histology. AC histology was more common in the nonsmoking group (62% of patients). SCC histology was seen in 54.3% of smokers. Metastasis to the contralateral lung and pleura was seen in 58.2% of patients.

CONCLUSION

NSCLC presents at a young age. Smoking is a significant risk factor and it is common in the urban populations as in the rural areas. Both AC and SCC histologies presented in equal proportions.

GAB2 Amplification in Squamous Cell Lung Cancer of Non-Smokers

Lung squamous cell cancer (SCC) is typically found in smokers and has a very low incidence in non-smokers, indicating differences in the tumor biology of lung SCC in smokers and non-smokers. However, the specific mutations that drive tumor growth in non-smokers have not been identified. To identify mutations in lung SCC of non-smokers, we performed a genetic analysis using arrays comparative genomic hybridization (ArrayCGH). We analyzed 19 patients with lung SCC who underwent surgical treatment between April 2005 and April 2015. Clinical characteristics were reviewed, and DNA was extracted from fresh frozen lung cancer specimens. All of copy number alterations from ArrayCGH were validated using The Cancer Genome Atlas (TCGA) copy number variation (CNV) data of lung SCC. We examined the frequency of copy number changes according to the smoking status (non-smoker [n = 8] or smoker [n = 11]). We identified 16 significantly altered regions from ArrayCGH data, three gain and four loss regions overlapped with the TCGA lung squamous cell carcinoma (LUSC) patients. Within these overlapped significant regions, we detected 15 genes that have been reported in the Cancer Gene census. We also found that the proto-oncogene GAB2 (11q14.1) was significantly amplified in non-smokers patients and vice versa in both ArrayCGH and TCGA data. Immunohistochemical analyses showed that GAB2 protein was relatively upregulated in non-smoker than smoker tissues (37.5% vs. 9.0%, P = 0.007). GAB2 amplification may have an important role in the development of lung SCC in non-smokers. GAB2 may represent a potential biomarker for lung SCC in non-smokers.

Should Never-Smokers at Increased Risk for Lung Cancer Be Screened?

INTRODUCTION

Lung cancer in never-smokers ranks among the 10 most common causes of death due to cancer worldwide and in the United States. However, it is unknown whether never-smokers at elevated risk for developing lung cancer may benefit from lung cancer screening.

METHODS

The MIcrosimulation SCreening ANalysis (MISCAN)-Lung microsimulation model was used to assess the effects of lung cancer screening for simulated cohorts of never-smokers at different levels of relative risk (RR) for lung cancer compared with never-smokers at average risk. The benefits and harms of screening were estimated for each cohort and compared with those of a cohort of ever-smokers eligible for lung cancer screening according to the United States Preventive Services Task Force (USPSTF) criteria.

RESULTS

The relative lung cancer mortality reduction in never-smokers was higher than the USPSTF eligible cohort (37% compared with 32%). However, the number of life-years gained per lung cancer death averted was lower (10.4 compared with 11.9) and the proportion of overdiagnosed cancers was higher (9.6% compared with 8.4%) for never-smokers compared with the USPSTF eligible cohort, as never-smokers are diagnosed at a later age. The estimated number of screens per lung cancer death averted ranged from 6162 for never-smokers at average risk to 151 for never-smokers with an RR of 35 compared with 353 for the USPSTF eligible cohort.

CONCLUSIONS

Never-smokers with RRs of 15 to 35 have similar to better trade-offs between benefits and harms compared with ever-smokers recommended for lung cancer screening by the USPSTF guidelines. For most never-smokers, lung cancer screening is not beneficial.

A note from history: Landmarks in history of cancer, part 7

In the 2 and half decades reviewed (1970-1995), research established that chromosomal translocation, deletion, and DNA amplification are prerequisites to cancerogenesis and that oncogenes, tumor-suppressor genes, growth factors, and cytokines play crucial roles in the pathomechanism of cancer. Human papillomavirus, human immunodeficiency virus, herpes virus, and hepatitis B virus were identified as cancer-causing viruses. Several laboratory tests were developed for the detection of primary and recurrent cancers, and cancer prevention by screening methods was popularized. Sonography, computerized tomography, magnetic resonance imaging, positron emission tomography, excision of sentinel lymph nodes, and immunohistochemical techniques became routine procedures. Clinicopathologic staging and classification of tumors were standardized. Limited surgery, adjuvant and neoadjuvant chemoradiation, and the therapeutic use of monoclonal antibodies, tumor vaccines, and targeted chemotherapy became routine practice. The decline in cancer incidence and mortality demonstrated that cancer prevention and advancement in oncology are pivotal to success in the crusade against cancer. Above all, it was clearly established that the care of patients with cancer can be accomplished best in a multidisciplinary setting involving surgical oncologists, radiologists, radiation therapists, medical oncologists, surgical pathologists, and laboratory scientists. In conclusion, the 25 years from 1970 and 1995 are the high-water mark in clinical oncology, and this is the period when oncology turned from art to science.

Alterations of a spectrum of driver genes in female Chinese patients with advanced or metastatic squamous cell carcinoma of the lung

OBJECTIVES

Female patients with squamous cell carcinomas of the lung (SQCLC) in China differ from male patients in that most females are life-long never/light smokers. We hypothesized that the clinical characteristics and mutation profiles of a spectrum of driver genes in Chinese female patients with advanced SQCLC would also differ from those of male patients.

PATIENTS AND METHODS

We examined the pathological subtype of SQCLC retrospectively by immunohistochemistry (IHC) and screened 38 female and 40 male patients with IIIB/IV-stage SQCLC in China from 2009 to 2012. Mutation analyses of EGFR, PIK3CA, KRAS, and PTEN were performed using PCR-based DNA sequencing. FGFR1 amplification and ALK rearrangements were detected by fluorescent in situ hybridization (FISH). A Cox regression model was used to assess the association between clinical features and genomic mutation status.

RESULTS

There were significantly fewer female patients with a history of smoking than males (5.3% vs. 90%; P<0.001). A younger average age at diagnosis (54.5 vs. 61 years; P=0.032) and a higher percentage of peripheral-type disease (47.4% vs. 25.0%; P=0.040) were observed in females. No difference in ECOG score, tumor size, metastatic status, or overall survival between females and males was seen. PIK3CA mutations were significantly less common in female patients than males (0/38 vs. 6/40; P=0.026). However, no significant difference in the mutational frequencies of EGFR, KRAS, PTEN, ALK, or FGFR1 was observed between females and males.

CONCLUSIONS

Our data demonstrated that female patients with SQCLC are apparently a subtype, with a significantly lower percentage having a smoking history, a younger average age at diagnosis, a higher percentage of peripheral-type disease on radiological presentation, and a lower frequency of PIK3CA mutations. Given the similar survival outcomes between the genders, whether it is a distinct disease entity needs to be studied further in larger populations.

Lung cancer incidence in Singapore: ethnic and gender differences

OBJECTIVES

Lung cancer is the leading cause of cancer death in Singapore. We examine trends of lung cancer from 1968 to 2007, explore ethnic and gender-specific incidence rates, and examine period and cohort effects in Chinese and Malays using Age-Period-Cohort (APC) analysis.

METHODS

Aggregated data for cancer incidences and estimated person-years for the period 1968-2007 were obtained from the Singapore Cancer Registry. An APC analysis was performed using a Poisson regression model.

RESULTS

Lung cancer incidence rates were more than two times higher in males compared to females, and also higher in Chinese compared to Malays and Indians. While rates in Chinese men, and, to a lesser extent, Chinese women, had been declining since the early 1980s, rates in Malay men continued to increase. The full APC model described the cancer trend in Chinese males, Chinese females and Malay males, while an age-drift model described the cancer trend in Malay females. Among Chinese males, Chinese females and Malay males, there was no clear pattern to the period curvature effects, although similar cohort curvatures were seen, with positive curvature effects in older cohorts that declined towards zero and negative effects in younger cohorts.

CONCLUSION

There are strong gender and ethnic differences in lung cancer incidence in Singapore. Differences in smoking rates and differential ethnic effects of smoking may explain some but not all of these differences. The similar cohort curvatures suggest that environmental factors in Singapore occurring in the past but no longer present at similar intensity or frequency may explain the positive deviation from a linear trend. Apart from smoking, other environmental factors such as changes in diet, improved sanitation and ventilation, and declines in infectious diseases like tuberculosis may play a role.

Worldwide trend of increasing primary adenocarcinoma of the lung

The four major histological types of lung cancer are adenocarcinoma, squamous cell carcinoma (SQ), large cell carcinoma and small cell carcinoma. Over the past few decades, the incidence of lung adenocarcinoma has increased gradually in most countries as the most frequently occurring histological type, displacing SQ. Adenocarcinoma is the predominant type of lung cancer among lifelong non-smokers and among females. Especially in East Asian countries, the cause(s) of the increase in adenocarcinomas are not clear. Several genetic mutations specific to lung adenocarcinomas have been found, representing attractive targets for molecular therapy. Recently, the pathological classification of lung adenocarcinoma was revised by integrating the newer clinical and biological knowledge concerning this prevailing type. Additional epidemiological, pathological and genetic studies are required to better understand this type of lung cancer.

EGFR polymorphisms, hormone replacement therapy and lung adenocarcinoma risk: analysis from a genome-wide association study in never-smoking women

Hormone replacement therapy (HRT) and epidermal growth factor receptor (EGFR) single nucleotide polymorphisms (SNPs) have been reported as risk factors for lung cancer in never smokers. We investigate the interaction of EGFR SNPs and HRT for lung adenocarcinoma risk in never-smoking women. This study included 532 never-smoking female lung adenocarcinoma patients and 532 controls, with EGFR SNPs retrieved from a genome-wide association study. The associations of EGFR SNPs with the lung adenocarcinoma risk were estimated by multivariate-adjusted logistic regression. The Haploview program was used to select tagged EGFR SNPs interacted with HRT and construct haplotype blocks. The Benjamini and Hochberg method was used to reduce the multiple testing effects. Among 84 EGFR SNPs retrieved, 11 tagging EGFR SNPs showed an interaction with HRT and lung adenocarcinoma risk, which were mostly located near the tyrosine kinase domain. Eight of the tagged SNPs were in two haplotype blocks. The interactions between HRT and numbers of protective EGFR SNP genotypes are significant in both blocks (P for interaction = 0.0004 and 0.0032, respectively). A trend of decrease in lung adenocarcinoma risk was found in subjects with HRT harboring an increasing number of protective EGFR SNP genotypes in both blocks (P = 0.0032 and 0.0046, respectively). In conclusion, HRT use may modify the association of EGFR SNPs with lung adenocarcinoma risk. The EGFR SNPs have a cumulative effect on decreasing lung adenocarcinoma risk in never-smoking women with HRT use.

Professional exposure to goats increases the risk of pneumonic-type lung adenocarcinoma: results of the IFCT-0504-Epidemio study

Pneumonic-type lung adenocarcinoma (P-ADC) represents a distinct subset of lung cancer with specific clinical, radiological, and pathological features. Given the weak association with tobacco-smoking and the striking similarities with jaagsiekte sheep retrovirus (JSRV)-induced ovine pulmonary adenocarcinoma, it has been suggested that a zoonotic viral agent infecting pulmonary cells may predispose to P-ADC in humans. Our objective was to explore whether exposure to domestic small ruminants may represent a risk factor for P-ADC. We performed a multicenter case-control study recruiting patients with P-ADC as cases and patients with non-P-ADC non-small cell lung cancer as controls. A dedicated 356-item questionnaire was built to evaluate exposure to livestock. A total of 44 cases and 132 controls were included. At multivariate analysis, P-ADC was significantly more associated with female gender (Odds-ratio (OR) = 3.23, 95% confidence interval (CI): 1.32–7.87, p = 0.010), never- smoker status (OR = 3.57, 95% CI: 1.27–10.00, p = 0.015), personal history of extra-thoracic cancer before P-ADC diagnosis (OR = 3.43, 95% CI: 1.10–10.72, p = 0.034), and professional exposure to goats (OR = 5.09, 95% CI: 1.05–24.69, p = 0.043), as compared to other subtypes of lung cancer. This case-control suggests a link between professional exposure to goats and P-ADC, and prompts for further epidemiological evaluation of potential environmental risk factors for P-ADC.

Aspirin and non-aspirin non-steroidal anti-inflammatory drug use and risk of lung cancer

There is evidence that aspirin and non-aspirin non-steroidal anti-inflammatory drug (NSAID) have anti-carcinogenic properties, but their effect on lung cancer, in particular in never-smokers, is unclear. Information on past or current use of anti-inflammatory medication was obtained in 398 Chinese female primary lung cancer cases and 814 controls in a hospital-based study in Singapore. 65% of cases and 88% of controls were never-smokers. Controls were excluded if they had been admitted for conditions associated with aspirin or NSAID use (n=174). Regular aspirin use (twice a week or more, for a month or more) was associated with a reduced risk of lung cancer (adjusted odds ratio [OR] 0.50, 95% confidence intervals [95%CI] 0.31-0.81 in non-smokers; OR 0.38, 95%CI 0.16-0.93 in smokers). Regular use of non-aspirin NSAID, paracetamol, steroid creams and steroid pills was uncommon and no association with lung cancer was detected. Our results suggest that aspirin consumption may reduce lung cancer risk in Asian women and are consistent with current understanding of the role of cyclooxygenase in lung carcinogenesis.

Effect of carcinogenic acrolein on DNA repair and mutagenic susceptibility

Acrolein (Acr), a ubiquitous environmental contaminant, is a human carcinogen. Acr can react with DNA to form mutagenic α- and γ-hydroxy-1, N(2)-cyclic propano-2'-deoxyguanosine adducts (α-OH-Acr-dG and γ-OH-Acr-dG). We demonstrate here that Acr-dG adducts can be efficiently repaired by the nucleotide excision repair (NER) pathway in normal human bronchial epithelia (NHBE) and lung fibroblasts (NHLF). However, the same adducts were poorly processed in cell lysates isolated from Acr-treated NHBE and NHLF, suggesting that Acr inhibits NER. In addition, we show that Acr treatment also inhibits base excision repair and mismatch repair. Although Acr does not change the expression of XPA, XPC, hOGG1, PMS2 or MLH1 genes, it causes a reduction of XPA, XPC, hOGG1, PMS2, and MLH1 proteins; this effect, however, can be neutralized by the proteasome inhibitor MG132. Acr treatment further enhances both bulky and oxidative DNA damage-induced mutagenesis. These results indicate that Acr not only damages DNA but can also modify DNA repair proteins and further causes degradation of these modified repair proteins. We propose that these two detrimental effects contribute to Acr mutagenicity and carcinogenicity.

The 18p11.22 locus is associated with never smoker non-small cell lung cancer susceptibility in Korean populations

The proportion of never smoker non-small cell lung cancer (NSCLC) in Asia is about 30-40%. Despite the striking demographics and high prevalence of never smoker NSCLC, the exact causes still remain undetermined. Although several genome wide association (GWA) studies were conducted to find susceptibility loci for lung cancer in never smokers, no regions were replicated except for 5p15.33, suggesting locus heterogeneity and different environmental toxic effects. To identify genetic loci associated with susceptibility of lung cancer in never smokers, we performed a GWA analysis using the Affymetrix 6.0 SNP array. For discovery GWA set, we recruited 446 never smoking Korean patients with NSCLC and 497 normal subjects. We tested association of SNPs with lung cancer susceptibility using the Cochran-Armitage trend test. For validation, 39 SNPs were selected from the top 50 SNPs and five additional SNPs were selected in the DAB1 gene region which showed significant associations in the GWA analysis. The validation SNPs were genotyped in an independent sample including 434 patients and 1,000 controls. Among the 44 validation SNPs, two SNPs (rs11080466 and rs11663246) near the APCDD1, NAPG and FAM38B genes in the 18p11.22 region were replicated. P value of rs11080466 was 1.08 × 10(-6) in the combined sets (2.68 × 10(-5) in the discovery set and 2.60 × 10(-3) in the validation set) and odds ratio was 0.68 (0.58-0.79). We observed similar association for rs11663246. Our result suggests the 18p11.22 region as a novel lung cancer susceptibility locus in never smokers.

Meat consumption and risk of lung cancer among never-smoking women

The relationship between diet and lung cancer, apart from the protective effect of fruit and vegetables, is poorly understood. Reports on the role of dietary components such as meat are inconsistent, and few studies include sufficient numbers of nonsmokers. We examined the relationship between meat consumption and never-smoking lung cancer in a hospital-based case-control study of Singapore Chinese women, a population with low smoking prevalence. Three hundred and ninety-nine cases and 815 controls were recruited, of whom 258 cases and 712 controls were never smokers. A standardized questionnaire (which included a food frequency questionnaire module) was administered by trained interviewers. Among these never smokers, fruit and vegetable intake were inversely associated with lung cancer risk. Seventy-two percent of meat consumed was white meat (chicken or fish). Meat consumption overall was inversely associated with lung cancer [adjusted odds ratio (OR), 0.88, 0.59 for second, third tertiles, P (trend) = .012]. An inverse relationship between fish consumption and lung cancer (adjusted OR, 0.81, 0.47 for 2nd, 3rd tertiles, P (trend) < .001) was observed. No association was seen between consumption of processed meats and lung cancer, nor between dietary heterocyclic amines and lung cancer. Our data suggest that fish consumption may be protective against lung cancer in never smokers.

Distinct clinical features and outcomes in never-smokers with nonsmall cell lung cancer who harbor EGFR or KRAS mutations or ALK rearrangement

BACKGROUND

The objectives of this study were to determine the proportions of major oncogenic alterations and to examine survival in genotype-specific subsets of never-smokers with nonsmall cell lung cancer (NSCLC).

METHODS

The authors concurrently analyzed mutations in the epidermal growth factor receptor (EGFR) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) genes and investigated anaplastic lymphoma kinase (ALK) gene rearrangements in samples from 229 never-smokers with NSCLC. ALK rearrangements were identified by fluorescent in situ hybridization and were confirmed by immunohistochemistry. Mutations in EGFR (exons 18 to 21) and KRAS (codons 12 and 13) were determined by direct sequencing.

RESULTS

Of 229 tumors, the frequency of EGFR mutations, ALK rearrangements, KRAS mutations, and no mutations (wild type [WT]) in any of the 3 genes (WT/WT/WT) was 48%, 8.3%, 3.5%, and 40.2%, respectively. All genetic alterations were mutually exclusive. The median progression-free survival after treatment with EGFR tyrosine kinase inhibitors (TKIs) was 12.8 months, 6.3 months, 2.1 months, and 1.6 months in patients with EGFR mutations, the WT/WT/WT genotype, KRAS mutations, and ALK rearrangements, respectively. In a Cox regression model, the adjusted hazard ratio for the risk of disease progression after treatment with EGFR TKIs was 0.59 (95% confidence interval [CI], 0.40-0.87; P = .008) for patients with EGFR mutations, 4.58 (95% CI, 2.07-10.15; P < .001) for patients with ALK rearrangements, and 4.23 (95% CI, 1.65-10.8; P = .003) for patients with KRAS mutations. Overall survival also differed significantly among genotypes.

CONCLUSIONS

To the authors' knowledge, this was the largest comprehensive and concurrent analysis to date of 3 major oncogenic alterations in a cohort of East Asian never-smokers with NSCLC. Because survival outcomes differed among genotypes, and drugs that target specific alterations currently are available, genetic profiling to identify genotype-specific subsets can lead to successful treatment with appropriate kinase inhibitors.

Non-small cell lung cancer in never smokers as a representative 'non-smoking-associated lung cancer': epidemiology and clinical features

Recent interest in lung cancer without a history of tobacco smoking has led to the classification of a distinct disease entity of 'non-smoking-associated lung cancer'. In this review article, we have made an overview of the recent literature concerning both the epidemiology and clinical features of lung cancer in never smokers, and have brought 'non-smoking-associated lung cancer' into relief. The etiology of lung cancer in never smokers remains indefinite although many putative risk factors have been described including secondhand smoking, occupational exposures, pre-existing lung diseases, diet, estrogen exposure, etc. Non-small cell lung cancer (NSCLC) in never smokers is clinically characterized by an increased incidence in females and a higher occurrence of adenocarcinoma in comparison to NSCLC in ever smokers in both surgical patients and non-resectable advanced-stage patients. Furthermore, the prognosis of never-smoking NSCLC is better than that of smoking-related NSCLC in both surgical patients and non-resectable advanced-stage patients. Recently recognized novel gene mutations such as EGFR (epidermal growth factor receptor) mutations are largely limited to never smokers or light smokers, and the expression of this gene is responsible for the clinical efficacy of gefitinib, an epidermal growth factor receptor-tyrosine kinase inhibitor. NSCLC with the EML4 (echinoderm microtubule-associated protein-like 4)-ALK (anaplastic lymphoma kinase) fusion gene is also more likely to occur in never smokers and in those with adenocarcinoma histology, and is expected to benefit from ALK inhibitors. In consideration of the future increase in never-smoking NSCLC or 'non-smoking-associated lung cancer', both clinical trials and investigations are needed.

Outcome and treatment strategy in female lung cancer: a single institution experience

PURPOSE

To assess the survival rate of female lung cancer treated at the Institute of Oncology of the Vilnius University, Lithuania during the period between 1996-2005.

MATERIALS AND METHODS

During the period between 1996-2005, 471 women diagnosed with lung cancer were treated at the Department of Thoracic Surgery and Oncology of the Institute of Oncology, Vilnius University. Data on morphology, stage and treatment was collected from the medical records. All lung cancer cases by histology were classified in two groups: non-small cell lung cancer (includes squamous cell carcinoma, large cell carcinoma, adenocarcinoma and other less common types) and small cell lung cancer. The vital status of the study group was assessed as of December 31, 2007, by passive follow-up, using data from the population registry. It was found that 411 (87.3%) of the patients had died. Survival was estimated according to the Kaplan-Meier method.

RESULTS

The median survival of female lung cancer diagnosed during 1996-2005 in Lithuania show to be 8.7 months (8.4 (95% CI 7.2-10.8) months with non-small cell lung cancer and 9.3 (95% CI 6.3-13.0) months with small-cell lung cancer). Survival was more than 20 months in resectable non-small cell lung cancer (stages I, II, IIIA). Non-small cell lung cancer survival in advanced stages was less than 7 months. Small-cell lung cancer patients median survival at limited and extended stages of the disease were 9.5 (95% CI 2.9-18.4) compared to 9.2 (95% CI 6.2-13.7) months. Non-small cell lung cancer patients most frequently were treated by surgery (27.0%), surgery and chemotherapy or radiotherapy (19.6%). Small cell lung cancer patient treatment included chemo and radiotherapy (27.0%), chemotherapy (19.0%), radiotherapy (17.5%), surgery (27.9%).

CONCLUSIONS

The single center study of female lung cancer diagnosed during 1996-2005 in Lithuania show a significantly better chance of survival in resectable non-small cell lung cancer. Advanced stages of the disease at the time of diagnosis and choice of treatment options of female lung cancer in the country still remains an issue.

Non-small cell lung cancer in never-smokers: a new disease entity?

Non-small cell lung cancer (NSCLC) in never-smokers is an increasing entity. It seems that it has a different pathogenesis, at least in some cases, making it more sensitive to targeted therapies. Two promising targets have so far been identified. This article gives an overview on the biologic background and latest developments in the treatment of this particular entity.

Epidemiology of lung cancer in women: risk factors, survival, and screening

OBJECTIVE

Lung cancer remains the leading cause of cancer mortality in both men and women. Tobacco use causes the vast majority of lung cancer in women but does not explain all cases, because about one in five women who develop lung cancer have never smoked.

CONCLUSION

Environmental exposures, genetic predisposition, hormonal factors, and viral infection may all play a role in lung cancer in women. A better understanding may provide an avenue to more effective screening, diagnosis, and therapy.

TP53 mutations in nonsmall cell lung cancer

The tumor suppressor gene TP53 is frequently mutated in human cancers. Abnormality of the TP53 gene is one of the most significant events in lung cancers and plays an important role in the tumorigenesis of lung epithelial cells. Human lung cancers are classified into two major types, small cell lung cancer (SCLC) and nonsmall cell lung cancer (NSCLC). The latter accounts for approximately 80% of all primary lung cancers, and the incidence of NSCLC is increasing yearly. Most clinical studies suggest that NSCLC with TP53 alterations carries a worse prognosis and may be relatively more resistant to chemotherapy and radiation. A deep understanding of the role of TP53 in lung carcinogenesis may lead to a more reasonably targeted clinical approach, which should be exploited to enhance the survival rates of patients with lung cancer. This paper will focus on the role of TP53 in the molecular pathogenesis, epidemiology, and therapeutic strategies of TP53 mutation in NSCLC.

Jaagsiekte sheep retrovirus transformation in Madin-Darby canine kidney epithelial cell three-dimensional culture

Jaagsiekte sheep retrovirus (JSRV) is the causative agent of a contagious lung cancer in sheep that shares similarities with human bronchioloalveolar carcinoma (BAC). JSRV is unique because the envelope gene (env) is the oncogene, as it can transform cells in culture and induce tumors in animals. The phosphatidylinositol 3-kinase (PI3K)-Akt-mTOR and H/N-Ras-MEK-mitogen-activated protein kinase (MAPK) pathways have been shown to be critical for Env transformation. However, the question still remains of how disruption of these pathways relates to tumor formation. To address this, JSRV Env transformation was studied in the context of epithelial structure, using the polarized Madin-Darby canine kidney (MDCK) epithelial cell three-dimensional (3-D) culture system. The results indicated that JSRV Env-transformed MDCK cells were larger and had full or multiple lumens, in contrast to the single lumens observed in controls. The altered phenotype was largely mediated by an increase in proliferation, in addition to overcoming the proliferative suppression signal. JSRV Env was not found to disrupt polarity or tight junctions or to inhibit lumen apoptosis. The PI3K-Akt-mTOR pathway was important for Env transformation in MDCK cells, although the mechanisms of action differed in 3-D and monolayer cultures. PI3K-dependent signaling to mTOR occurred in monolayers, while PI3K-independent signaling to mTOR occurred in 3-D culture. In contrast, the H/N-Ras-MEK-MAPK pathway was found to be inhibitory to transformation in both normal and transformed MDCK cells in 3-D culture. However, in monolayer culture, inhibition of MEK reverted the transformed phenotype, suggesting a different mechanism(s) of action in monolayer versus 3-D culture.

Analysis of genetic variants in never-smokers with lung cancer facilitated by an Internet-based blood collection protocol: a preliminary report

PURPOSE

Germ line polymorphisms may confer susceptibility to lung cancer in never smokers, but studies in the United States have been limited by the low number of cases seen at single institutions. We hypothesized that we could use the Internet to bolster the accrual of appropriate patients.

EXPERIMENTAL DESIGN

We established an Internet-based protocol to collect blood and information from patients throughout the United States. To illustrate the power of this approach, we used these samples, plus additional cases and age-matched controls from the Memorial Sloan-Kettering Cancer Center (New York, NY) and the Aichi Cancer Center (Nagoya, Japan), to analyze germ line DNA for genetic variants reportedly associated with lung cancer susceptibility. The genotypes for the polymorphisms rs763317 (intron 1) and T790M (exon 20) in the EGFR gene were determined by direct sequencing, and CHRNA3 nicotinic acetylcholine receptor single nucleotide polymorphisms (rs8034191 and rs1051730) were genotyped as part of a pilot genome-wide association study.

RESULTS

We successfully analyzed germ line DNA from 369 cases, including 45 obtained via the Internet, and 342 controls. A germ line EGFR T790M variant was identified in 2 of the 369 cases (0.54%; 95% confidence interval, 0.21-1.29%), and in none of the 292 controls (P = 0.21). No difference was observed in EGFR rs763317 frequency between cases and controls. Similarly, neither CHRNA3 rs8034191 nor rs1051730 were associated with lung cancer risk.

CONCLUSIONS

The Internet provides a way to recruit patients throughout the country for minimal risk studies. This approach could be used to facilitate studies of germ line polymorphisms in specific groups of patients with cancer.

Human papilloma virus and female lung adenocarcinoma

Lung cancer is the leading cause of cancer among women worldwide, and adenocarcinoma is the most common histological subtype among non-smoking women. Previous studies showed that human papillomavirus (HPV) infection may relate to the tumorigenesis of pulmonary adenocarcinoma. Women with anogenital malignancy have a higher risk of lung cancer, which raises the possibility of HPV transmission from the cervix to the lung. Two postulated pathways are discussed in this work. First, HPV may infect the female cervix and then move to the lung by blood circulation. The second transmission route is the HPV infection of oral cavity resulting from dangerous sexual contacts, and subsequently transmitted to the lung. This chapter also reviews the techniques for detecting the existence, subtypes, and viral load of HPV. Future studies are needed to demonstrate the causal inference between HPV infection and the risk of female lung adenocarcinoma.

Interactive effect of cigarette smoking with human 8-oxoguanine DNA N-glycosylase 1 (hOGG1) polymorphisms on the risk of lung cancer: a case-control study in Taiwan

Human 8-oxoguanine DNA N-glycosylase 1 (hOGG1) plays an important role in repairing oxidative DNA damage induced by tobacco carcinogens. In this case-control study, the authors examined the interactive effect of hOGG1 gene polymorphisms and cigarette smoking on the risk of lung cancer in Taiwan. A total of 1,096 cases and 1,007 controls were enrolled from 6 medical centers in Taiwan during 2002-2004. hOGG1 Ser326Cys genetic polymorphisms were determined using the MassARRAY system (SEQUENOM, Inc., San Diego, California). Tobacco smoking history was obtained through personal interview according to a structured questionnaire. Logistic regression analysis was used to estimate multivariate-adjusted odds ratios and 95% confidence intervals. The odds of developing lung cancer for persons with the Cys/Cys genotype versus the Ser/Ser genotype were 1.11 (95% confidence interval (CI): 0.74, 1.65) for never smokers, 1.45 (95% CI: 0.74, 2.83) for moderate smokers, and 3.52 (95% CI: 1.54, 8.06) for heavy smokers. The P value for interaction in the logistic model was 0.01. The increased risk associated with the Cys/Cys genotype among heavy smokers remained statistically significant for various histologic types of lung cancer, including adenocarcinoma, squamous cell carcinoma, and small cell carcinoma. The authors conclude that there was a noticeable modifying effect on the association between hOGG1 genotype and lung cancer risk by cigarette smoking status.

Relationships between lung adenocarcinoma and gender, age, smoking and occupational risk factors: A case-case study

BACKGROUND

The hypothesis that some risk factors for lung cancer may have more specific associations with particular histologic types remains controversial. The aim of this study was to investigate possible associations between adenocarcinoma and gender, age, smoking characteristics and selected occupational carcinogens in relation to other histologic types.

METHODS

This study included all histologically confirmed lung cancer cases diagnosed consecutively in two French University hospitals from 1997 to 2006. All medical data were obtained by face-to-face patient interviews. Occupational carcinogen exposures of each patient were assessed by an industrial hygienist. Relationships between risk factors and adenocarcinoma were analyzed by case-case comparisons using unconditional logistic regressions (ULRs).

RESULTS

A total of 1493 subjects were enrolled in this study, comprising 1303 men (87.3%), 67 nonsmokers (4.5%) and 489 adenocarcinomas (32.7%). Using ULR, no associations were observed between adenocarcinoma and age, gender or smoking characteristics except for a negative relationship with smoking duration (p<0.0001). Significant associations were observed between ADC and exposure to welding fumes and silica in the whole population and with polycyclic aromatic hydrocarbons in ever smokers.

CONCLUSION

This study demonstrated that some risk factors, such as duration of smoking and certain occupational exposures but not gender or age, have a more important influence on the incidence of lung ADC than on other histologic types. As the distribution of histologic types may reflect underlying biological mechanisms, these findings also suggest that lung carcinogenesis pathways should be studied in relation to smoking duration and other lung cancer risk factors.

Traffic air pollution and lung cancer in females in Taiwan: petrol station density as an indicator of disease development

To investigate the relationship between traffic air pollution exposure and development of lung cancer in females, studies were conducted using a matched cancer case-control model into deaths that occurred in Taiwan from 1997 through 2006. Data on all eligible lung cancer deaths in females were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. The control group consisted of women who died from causes other than neoplasms or diseases that were associated with respiratory problems. The controls were pair matched to the cancer cases by year of birth and year of death. Each matched control was selected randomly from the set of possible controls for each case. Data on the number of petrol stations in study municipalities were collected from the two major petroleum supply companies, Chinese Petroleum Corporation (CPC) and Formosa Petrochemical Corporation (FPCC). The petrol station density (per square kilometer; PSD) for study municipalities was used as an indicator of a subject's exposure to benzene and other hydrocarbons present in ambient evaporative losses of petrol or to air emissions from motor vehicles. The subjects were divided into tertiles according to PSD in their residential municipality. The results showed that there was a significant exposure-response relationship between PSD and risk of lung cancer in females after controlling for possible confounders. The findings of this study warrant further investigation of the role of traffic air pollution exposure in the etiology of lung cancer.

Molecular genetics of lung cancer in people who have never smoked

Lung cancer is a major cause of cancer-related mortality in the USA, and tobacco smoke is the major risk factor for this disease. However, many patients with lung cancer have never smoked (never smokers). Patients with lung cancer who have never smoked are more likely to have mutations in epidermal growth factor receptor (EGFR) tyrosine kinase and have better response to its inhibitors than do patients with tobacco-associated lung cancer. Furthermore, the prevalences of mutations in KRAS and P53 differ for patients with lung cancer who have never smoked and those with tobacco-associated lung cancer. Genetic mutations seem to be more common in patients with tobacco-associated lung cancer than in never smokers. Current evidence indicates that the two types of lung cancer are biologically distinct. Here, we review published studies of the molecular genetics of lung cancer in never smokers and identify the specific differences from tobacco-associated lung cancer.

Docetaxel plus gemcitabine as front-line chemotherapy in elderly patients with lung adenocarcinomas: a multicenter phase II study

BACKGROUND

The docetaxel/gemcitabine (DG) combination is an active and well-tolerated regimen against non-small cell lung cancer (NSCLC). A phase II study was conducted in order to evaluate its efficacy in elderly patients with lung adenocarcinomas.

METHODS

Chemotherapy-naive patients, aged > or =70 years, with locally advanced or metastatic lung adenocarcinomas and performance status (PS) < or =2 (ECOG) received gemcitabine 1100 mg/m(2) (days 1+8) and docetaxel 100 mg/m(2) (day 8) with rhG-CSF support.

RESULTS

Seventy-seven patients were enrolled. One (1.3%) complete and 23 (29.9%) partial responses were achieved (intention to treat analysis: ORR 31.2%; 95% CI 20.82-41.51%) whereas tumor growth control was achieved in 53.3% of patients. The median TTP was 4.1 months, the median overall survival 9.4 months and the 1- and 2-year survival rate 37.9% and 10.7%, respectively. Grade 3-4 neutropenia occurred in 18.2% and febrile neutropenia in 3 (3.9%) patients. Non-haematological toxicity was mild with grade 2-3 asthenia occurring in 22.1% patients.

CONCLUSIONS

The DG regimen is an active and well-tolerated front-line chemotherapy for elderly patients with lung adenocarcinomas and merits further evaluation in prospective randomized trials.

Ambient exposure to criteria air pollutants and female lung cancer in Taiwan

To investigate the relationship between air pollution and female lung cancer, the authors conducted a matched case-control study using female deaths that occurred in Taiwan from 1995 through 2005. Data on all eligible female lung cancer deaths were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. The control group consisted of women who died from causes other than cancer or diseases associated with respiratory problems. The controls were pair-matched to the cases by sex, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each case. Classification of exposure to municipality air pollution was based on the measured levels of nitrogen dioxide and carbon monoxide. The results of the present study show that there is a significant positive association between the levels of air pollution and female lung cancer mortality. The adjusted odds ratios (95% confidence interval) were 1.24 (1.03-1.50) for the group with medium air pollution level and 1.46 (1.18-1.81) for the group with high air pollution level when compared to the group with the low air pollution level. Trend analyses showed statistically significant trend in risk of female lung cancer with increasing air pollution level. The findings of this study warrant further investigation of the role of air pollutants in the etiology of lung cancer.