The growing burden of chronic obstructive pulmonary disease and lung cancer in women: examining sex differences in cigarette smoke metabolism

Gender differences in pulmonary regenerative response to naphthalene-induced bronchiolar epithelial cell injury

OBJECTIVES

Accumulating evidence suggests that gender affects the incidence and severity of several pulmonary diseases. Previous studies on mice have shown gender differences in susceptibility to naphthalene-induced lung injury, where Clara cell damage was found to occur earlier and to be more extensive in females than in males. However, very little is known about whether there are any gender differences in subsequent lung repair responses. The aim of this study was to investigate whether gender plays an important role in pulmonary regenerative response to naphthalene-induced Clara cell ablation.

MATERIALS AND METHODS

Adult male and female mice were injected with a low, medium, or high dose of naphthalene, and lung tissue regeneration was examined by immunohistochemical staining for cell proliferation marker (Ki-67) and mitosis marker (phosphohistone-3).

RESULTS

Histopathological analysis showed that naphthalene-induced Clara cell necrosis was more prominent in the lungs of female mice as compared to male mice. Cell proliferation and mitosis in both the distal bronchiolar airway epithelium and peribronchiolar interstitium of female mice was significantly greater than that of male mice after treatment with the low and medium doses. However, after treatment with high dose of naphthalene, lung regeneration was delayed in female mice, while male mice mounted a timely regenerative response.

CONCLUSIONS

These findings show that there are clear gender differences in naphthalene-induced lung injury and repair.

Chronic obstructive lung diseases and risk of non-small cell lung cancer in women

INTRODUCTION

The link between lung cancer and chronic obstructive lung diseases (COPD) has not been well studied in women even though lung cancer and COPD account for significant and growing morbidity and mortality among women.

METHODS

We evaluated the relationship between COPD and non-small cell lung cancer in a population-based case-control study of women and constructed a time course of chronic lung diseases in relation to onset of lung cancer. Five hundred sixty-two women aged 18 to 74, diagnosed with non-small cell lung cancer and 564 population-based controls matched on race and age participated. Multivariable unconditional logistic regression models were used to estimate risk associated with a history of COPD, chronic bronchitis, or emphysema.

RESULTS

Lung cancer risk increased significantly for white women with a history of COPD (odds ratios [OR] = 1.85; 95% confidence intervals [CI]: 1.21-2.81), but this was not seen in African American women. Risk associated with a history of chronic bronchitis was strongest when diagnosed at age 25 or earlier (OR = 2.35, 95% CI: 1.17-4.72); emphysema diagnosed within 9 years of lung cancer was also associated with substantial risk (OR = 6.36, 95% CI: 2.36-17.13). Race, pack-years of smoking, exposure to environmental tobacco smoke as an adult, childhood asthma, and exposure to asbestos were associated with a history of COPD among lung cancer cases.

CONCLUSIONS

In women, COPD is associated with risk of lung cancer differentially by race. Untangling whether COPD is in the causal pathway or simply shares risk factors will require future studies to focus on specific COPD features, while exploring underlying genetic susceptibility to these diseases.

Lung cancer and chronic obstructive pulmonary disease: needs and opportunities for integrated research

Lung cancer and chronic obstructive pulmonary disease (COPD) are leading causes of morbidity and mortality in the United States and worldwide. They share a common environmental risk factor in cigarette smoke exposure and a genetic predisposition represented by the incidence of these diseases in only a fraction of smokers. The presence of COPD increases the risk of lung cancer up to 4.5-fold. To investigate commonalities in disease mechanisms and perspectives for disease chemoprevention, the National Heart, Lung, and Blood Institute (NHLBI) and the National Cancer Institute (NCI) held a workshop. The participants identified four research objectives: 1) clarify common epidemiological characteristics of lung cancer and COPD; 2) identify shared genetic and epigenetic risk factors; 3) identify and validate biomarkers, molecular signatures, and imaging-derived measurements of each disease; and 4) determine common and disparate pathogenetic mechanisms. These objectives should be reached via four research approaches: 1) identify, publicize, and enable the evaluation and analysis of existing datasets and repositories of biospecimens; 2) obtain phenotypic and outcome data and biospecimens from large studies of subjects with and/or at risk for COPD and lung cancer; 3) develop and use animal and other preclinical models to investigate pathogenetic links between the diseases; and 4) conduct early-phase clinical trials of potential chemopreventive agents. To foster much needed research interactions, two final recommendations were made by the participants: 1) incorporate baseline phenotyping and outcome measures for both diseases in future longitudinal studies of each disease and 2) expand collaborative efforts between the NCI and NHLBI.

Women and lung cancer: clinical and molecular profiling as a determinate for treatment decisions: a literature review

In the past decade the incidence of lung cancer among women has risen, whereas among men it has slightly declined. Important differences in lung cancer have been demonstrated between men and women, although many areas still remain controversial. Some biologic differences may justify the increase in response of women to therapy for lung cancer and can partially explain the improved survival of women compared with men. We extensively reviewed the published scientific literature on this topic in order to investigate the clinical and genetic profiling underlying lung cancer in women and to use this information as a tool for medical therapy.

Gender and chronic obstructive pulmonary disease: why it matters

The prevalence of chronic obstructive pulmonary disease (COPD) in women is increasing, as is hospitalization for COPD. The number of women dying of COPD in the United States now surpasses men. Despite this, research suggests that physicians are still more likely to correctly diagnose men with COPD than women. Increased tobacco use in women likely explains some of the increase in the prevalence of COPD in women, but data suggest that women may actually be at greater risk of smoking-induced lung function impairment, more severe dyspnea, and poorer health status for the same level of tobacco exposure. The degree to which these observations represent biologic, physiologic, or sociologic differences is not known. Nonsmokers with COPD are also more likely to be female. In addition, new evidence is emerging that men and women may be phenotypically different in their response to tobacco smoke, with men being more prone to an emphysematous phenotype and women an airway predominant phenotype. Inasmuch as COPD is a disease of inflammation, it is also possible that sexual dimorphism of the human immune response may also be responsible for gender differences in the disease. More data are still needed on what the implications of these findings are on therapy. In this clinical commentary, we present current knowledge regarding how gender influences the epidemiology, diagnosis, and presentation of COPD in addition to physiologic and psychologic impairments and we attempt to offer insight into why these differences might exist and how this may influence therapeutic management.

Six-second spirometry for detection of airway obstruction: a population-based study in Austria

RATIONALE

The presence of airway obstruction is currently defined by Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines on the basis of the post-bronchodilator (BD) FEV(1)/FVC. It has been proposed that the traditional FVC can be replaced with the shorter and less demanding FEV(6) for detecting airway obstruction.

OBJECTIVES

A comparison of FEV(1)/FVC and FEV(1)/FEV(6) for the detection of airway obstruction in population-based post-bronchodilator spirometry data.

METHODS

A population-based sample of 1,349 adults participated in the Burden of Obstructive Lung Disease study in Austria. Specially trained and certified technicians conducted pre-BD and post-BD spirometry according to American Thoracic Society guidelines and administered standardized questionnaires. A total of 93% of the post-BD test sessions were acceptable, and were included in this analysis. The Third National Health and Nutrition Examination Survey reference equations were used to calculate predicted values and lower limits of normal (LLN) for FEV(1), FEV(6), FVC, FEV(1)/FVC, and FEV(1)/FEV(6).

MEASUREMENTS AND MAIN RESULTS

The post-BD FEV(1)/FVC was below the LLN in 199 (15.8%) subjects. The sensitivity of the FEV(1)/FEV(6) for airway obstruction depended greatly on the threshold of percent predicted FEV(1) also used in the definition. The overall sensitivity of FEV(1)/FEV(6) for a diagnosis of airway obstruction, as defined by FEV(1)/FVC (including participants with an FEV(1) above the LLN), was 72.9%, with 98.8% specificity. The sensitivity increased to 98.0% when a low FEV(1) was also required to diagnose post-BD airway obstruction. The discordant cases had long forced expiratory times, often showed a flow-volume curve pattern consistent with two-compartment emptying, and were more often never-smokers.

CONCLUSIONS

Six-second spirometry maneuvers (which measure FEV(6)) are as sensitive and specific for post-BD airway obstruction as traditional (prolonged exhalation time) FVC maneuvers only when the definition of airway obstruction includes a low FEV(1).