The influence of fluticasone inhalation on markers of carcinogenesis in bronchial epithelium

Inhaled corticosteroids and risk of lung cancer: A systematic review and meta-analysis

INTRODUCTION

Current studies investigating the association between inhaled corticosteroid (ICS) use and risk of lung cancer have yielded inconsistent findings. The aim of this systematic review and meta-analysis was to pool all currently available data to estimate this association.

METHODS

We systematically searched MEDLINE (1946 to July 2020), EMBASE (1974 to July 2020) and the Cochrane Library (June 2020) via Ovid to identify relevant articles investigating the association between the ICS use and the risk of lung cancer. Random-effects analysis was used to calculate pooled relative risks (RRs) with 95% confidence intervals (CIs).

RESULTS

Ten articles including 234 920 patients were analysed. ICS use was identified to have a decreased risk of lung cancer in chronic obstructive pulmonary disease (8 studies, 1806 patients; RR = 0.73, 95% CI: 0.61-0.87, P < .01; I²  = 60.0 %), asthma (1 study, 41 438 patients; RR = 0.44, 95% CI: 0.34-0.57, P < .01) and mixed (1 study, 46 225 patients; RR = 0.79, 95% CI: 0.69-0.90, P < .01) patients. The findings of reduced risk of lung cancer were consistent in all subgroup analyses except for the short-term follow-up (≤5 years) (RR = 0.94, 95% CI: 0.81-1.07, P = .34) and free of immortal time bias (RR = 0.94, 95% CI: 0.82-1.08, P = .38) subgroups.

CONCLUSIONS

The present study suggested that ICS use was associated with decreased risk of lung cancer. However, our findings should be interpreted with caution because most original studies were judged to be at high risk of immortal time bias.

Role of chronic obstructive pulmonary disease in lung cancer pathogenesis

Chronic obstructive pulmonary disease (COPD) and lung cancer are two important smoking related conditions. However, COPD has been shown to be an independent risk factor for lung cancer regardless of smoking history, suggesting that COPD and lung cancer may share a common pathogenesis. This review summarizes the epidemiology of lung cancer and COPD briefly, as well as discussing the potential for shared genetic risk, and shared genomic mechanisms, such as epigenetic changes or DNA damage induced by smoking. How key areas of COPD pathogenesis, such as inflammation, oxidative stress and protease imbalance may contribute to subsequent development of cancer will also be covered. Finally the possibility that consequences of COPD, such as hypoxia, influence carcinogenesis will be reviewed. By understanding the pathogenesis of COPD and lung cancer in detail it is possible that new treatments may be developed and the risk of lung cancer in COPD may be reduced.

Chronic obstructive pulmonary disease and lung cancer: new molecular insights

Both chronic obstructive pulmonary disease (COPD) and lung cancer are major causes of death worldwide. In most cases this reflects cigarette smoke exposure which is able to induce an inflammatory response in the airways of smokers. Indeed, COPD is characterized by lower airway inflammation, and importantly, the presence of COPD is by far the greatest risk factor for lung cancer amongst smokers. Cigarette smoke induces the release of many inflammatory mediators and growth factors including TGF-β, EGFR, IL-1, IL-8 and G-CSF through oxidative stress pathways and this inflammation may persist for decades after smoking cessation. Mucus production is also increased by these inflammatory mediators, further linking airway inflammation to an important mechanism of lung cancer. A greater understanding of the molecular and cellular pathobiology that distinguishes smokers with lung cancer from smokers with and without COPD is needed to unravel the complex molecular interactions between COPD and lung cancer. By understanding the common signalling pathways involved in COPD and lung cancer the hope is that treatments will be developed that not only treat the underlying disease process in COPD, but also reduce the currently high risk of developing lung cancer in these patients.

Common pathogenic mechanisms and pathways in the development of COPD and lung cancer

INTRODUCTION

Lung cancer and COPD commonly coexist in smokers, and the presence of COPD increases the risk of developing lung cancer. In addition to smoking cessation and preventing smoking initiation, understanding the shared mechanisms of these smoking-related lung diseases is critical, in order to develop new methods of prevention, diagnosis and treatment of lung cancer and COPD.

AREAS COVERED

This review discusses the common mechanisms for susceptibility to lung cancer and COPD, which in addition to cigarette smoke, may involve inflammation, epithelial-mesenchymal transition, abnormal repair, oxidative stress, and cell proliferation. Furthermore, we discuss the underlying genomic and epigenomic changes (single nucleotide polymorphisms (SNPs), copy number variation, promoter hypermethylation and microRNAs) that are likely to alter biological pathways, leading to susceptibility to lung cancer and COPD (e.g., altered nicotine receptor biology).

EXPERT OPINION

Strategies to study genomics, epigenomics and gene-environment interaction will yield greater insight into the shared pathogenesis of lung cancer and COPD, leading to new diagnostic and therapeutic modalities.

Randomized phase II trial of inhaled budesonide versus placebo in high-risk individuals with CT screen-detected lung nodules

Screening CT identifies small peripheral lung nodules, some of which may be pre- or early invasive neoplasia. Secondary end point analysis of a previous chemoprevention trial in individuals with bronchial dysplasia showed reduction in size of peripheral nodules by inhaled budesonide. We performed a randomized, double-blind, placebo-controlled phase IIb trial of inhaled budesonide in current and former smokers with CT-detected lung nodules that were persistent for at least 1 year. A total of 202 individuals received inhaled budesonide, 800 μg twice daily or placebo for 1 year. The primary endpoint was the effect of treatment on target nodule size in a per person analysis after 1 year. The per person analysis showed no significant difference between the budesonide and placebo arms (response rate 2% and 1%, respectively). Although the per lesion analysis revealed a significant effect of budesonide on regression of existing target nodules (P = 0.02), the appearance of new lesions was similar in both groups and thus the significance was lost in the analysis of all lesions. The evaluation by nodule type revealed a nonsignificant trend toward regression of nonsolid and partially solid lesions after budesonide treatment. Budesonide was well tolerated, with no unexpected side effects identified. Treatment with inhaled budesonide for 1 year did not significantly affect peripheral lung nodule size. There was a trend toward regression of nonsolid and partially solid nodules after budesonide treatment. Because a subset of these nodules is more likely to represent precursors of adenocarcinoma, additional follow-up is needed.

The finding of premalignant lesions is not associated with smoking cessation in chemoprevention study volunteers

BACKGROUND AND STUDY AIMS

Screening programs for lung cancer may lead to a heightened awareness of the risks of smoking and enhance quitting. The aim of this study was to evaluate whether the participation on a chemoprevention study for premalignant lesions could influence smoking cessation.

METHODS

Two hundred one volunteers, current (n = 188) and former smokers (n = 13) with more than 20 pack years had been screened for the chemoprevention study. One hundred forty-six of the current smokers at time of chemoprevention study screening have been retrospectively interviewed about their smoking behavior > or =1 year after their first contact for the chemoprevention study. Structured questionnaires were used, and interviews were held by telephone. The quitters at the time of these first interviews were contacted again 4 years after the initial interview about their current smoking behavior.

RESULTS

Of the 146 smoking volunteers, 83 were diagnosed with premalignant lesions of the bronchial mucosa and participated in the chemoprevention study, and 63 had no premalignant lesions and were not included in that study.The majority of participants were men: 87 (60%). The mean age of the participants was 52 +/- 9 years, and the mean age at which volunteers started smoking was 15 +/- 3. Mean number of pack years was 47 +/- 27. Ten volunteers in the group without premalignant lesions and 19 in the group with premalignant lesions had quit smoking at time of the first interview. The smoking cessation rate of the total study group was 20%.Univariate logistic regression analysis demonstrated that smoking cessation was only significantly associated with male gender. No significant associations were found between smoking cessation and the finding of premalignant lesions, sex, age, level of addiction, educational level, marital condition, history of cancer/pulmonary diseases, age at start smoking, previous attempts to quit smoking, and motivation to quit smoking.Within the group of subjects who had quit smoking at the time of the first interview, 15 of 29 persons who had stopped smoking at the time of the first interview have reported that participation in the bronchoscopy screening and/or the trial has been of major influence on their decision to stop smoking.

CONCLUSIONS

A smoking cessation rate of 20% has been found among volunteers for a chemopreventive trial investigating smoking-related premalignant lesions after almost 2 years after initial contact has been found. Volunteers experienced screening and trial participation as having influenced their smoking cessation. Smoking cessation was significantly associated with male gender, whereas the finding of premalignant lesions by bronchoscopy was not.

Chemoprevention of lung cancer

Lung cancer is the leading cause of cancer death in the United States, and the majority of diagnoses are made in former smokers. While avoidance of tobacco abuse and smoking cessation clearly will have the greatest impact on lung cancer development, effective chemoprevention could prove to be more effective than treatment of established disease. Chemoprevention is the use of dietary or pharmaceutical agents to reverse or inhibit the carcinogenic process and has been successfully applied to common malignancies other than lung. Despite previous studies in lung cancer chemoprevention failing to identify effective agents, our ability to determine higher risk populations and the understanding of lung tumor and pre-malignant biology continues to advance. Additional biomarkers of risk continue to be investigated and validated. The World Health Organization/International Association for the Study of Lung Cancer classification for lung cancer now recognizes distinct histologic lesions that can be reproducibly graded as precursors of non-small cell lung cancer. For example, carcinogenesis in the bronchial epithelium starts with normal epithelium and progresses through hyperplasia, metaplasia, dysplasia, and carcinoma in situ to invasive squamous cell cancer. Similar precursor lesions exist for adenocarcinoma, and these pre-malignant lesions are targeted by chemopreventive agents in current and future trials. At this time, chemopreventive agents can only be recommended as part of well-designed clinical trials, and multiple trials are currently in progress and additional trials are in the planning stages. This review will discuss the principles of chemoprevention, summarize the completed trials, and discuss ongoing and potential future trials with a focus on targeted pathways.

A randomized phase II chemoprevention trial of 13-CIS retinoic acid with or without alpha tocopherol or observation in subjects at high risk for lung cancer

No chemoprevention strategies have been proven effective for lung cancer. We evaluated the effect of 13-cis retinoic acid (13-cis RA), with or without alpha tocopherol, as a lung cancer chemoprevention agent in a phase II randomized controlled clinical trial of adult subjects at high risk for lung cancer as defined by the presence of sputum atypia, history of smoking, and airflow obstruction, or a prior surgically cured nonsmall cell lung cancer (disease free, >3 years). Subjects were randomly assigned to receive either 13-cis RA, 13-cis RA plus alpha tocopherol (13-cis RA/alpha toco) or observation for 12 months. Outcome measures are derived from histologic evaluation of bronchial biopsy specimens obtained by bronchoscopy at baseline and follow-up. The primary outcome measure is treatment "failure" defined as histologic progression (any increase in the maximum histologic score) or failure to return for follow-up bronchoscopy. Seventy-five subjects were randomized (27/22/26 to observations/13-cis RA/13-cis RA/alpha toco); 59 completed the trial; 55 had both baseline and follow-up bronchoscopy. The risk of treatment failure was 55.6% (15 of 27) and 50% (24 of 48) in the observation and combined (13 cis RA plus 13 cis RA/alpha toco) treatment arms, respectively (odds ratio adjusted for baseline histology, 0.97; 95% confidence interval, 0.36-2.66; P = 0.95). Among subjects with complete histology data, maximum histology score in the observation arm increased by 0.37 units and by 0.03 units in the treated arms (difference adjusted for baseline, -0.18; 95% confidence interval, -1.16 to 0.81; P = 0.72). Similar (nonsignificant) results were observed for treatment effects on endobronchial proliferation as assessed by Ki-67 immunolabeling. Twelve-month treatment with 13-cis RA produced nonsignificant changes in bronchial histology, consistent with results in other trials. Agents advancing to phase III randomized trials should produce greater histologic changes. The addition of alpha tocopherol did not affect toxicity.

CT detected indeterminate pulmonary nodules in a chemoprevention trial of fluticasone

INTRODUCTION

In animal models of lung carcinogenesis, inhaled corticosteroids appear to reduce the number of new lung tumors. In a trial of budesonide in smokers with bronchial dysplasia, the proportion of indeterminate CT detected pulmonary nodules that resolved was larger in the treatment group. We performed a secondary analysis of CT data of subjects at risk of lung cancer enrolled in a chemoprevention trial of fluticasone.

METHODS

Subjects with bronchial squamous metaplasia or dysplasia had a baseline chest CT scan. They were randomized to fluticasone or a placebo. After 6 months a repeat CT was performed and the change in number and size of nodules was evaluated.

RESULTS

Two hundred and one subjects were screened. Of the 108 volunteers included in the study, 74 were male, mean age was 53 years and mean number of pack years 48. Baseline: 35 subjects had 91 nodules in total, 62% <4mm. In the fluticasone arm more subjects had a decrease and fewer had an increase in number of nodules, however this trend did not reach statistical significance.

CONCLUSION

In this preliminary study there was a tendency of nodules to resolve, however, studies with CT detected nodules as inclusion criterion are needed.