Chest CT screening of asbestos-exposed workers: lung lesions and incidental findings

ERS/ESTS/ESTRO/ESR/ESTI/EFOMP statement on management of incidental findings from low dose CT screening for lung cancer

BACKGROUND

Screening for lung cancer with low radiation dose computed tomography has a strong evidence base, is being introduced in several European countries and is recommended as a new targeted cancer screening programme. The imperative now is to ensure that implementation follows an evidence-based process that will ensure clinical and cost effectiveness. This European Respiratory Society (ERS) task force was formed to provide an expert consensus for the management of incidental findings which can be adapted and followed during implementation.

METHODS

A multi-European society collaborative group was convened. 23 topics were identified, primarily from an ERS statement on lung cancer screening, and a systematic review of the literature was conducted according to ERS standards. Initial review of abstracts was completed and full text was provided to members of the group for each topic. Sections were edited and the final document approved by all members and the ERS Science Council.

RESULTS

Nine topics considered most important and frequent were reviewed as standalone topics (interstitial lung abnormalities, emphysema, bronchiectasis, consolidation, coronary calcification, aortic valve disease, mediastinal mass, mediastinal lymph nodes and thyroid abnormalities). Other topics considered of lower importance or infrequent were grouped into generic categories, suitable for general statements.

CONCLUSIONS

This European collaborative group has produced an incidental findings statement that can be followed during lung cancer screening. It will ensure that an evidence-based approach is used for reporting and managing incidental findings, which will mean that harms are minimised and any programme is as cost-effective as possible.

ERS/ESTS/ESTRO/ESR/ESTI/EFOMP statement on management of incidental findings from low dose CT screening for lung cancer

BACKGROUND

Screening for lung cancer with low radiation dose computed tomography has a strong evidence base, is being introduced in several European countries and is recommended as a new targeted cancer screening programme. The imperative now is to ensure that implementation follows an evidence-based process that will ensure clinical and cost effectiveness. This European Respiratory Society (ERS) task force was formed to provide an expert consensus for the management of incidental findings which can be adapted and followed during implementation.

METHODS

A multi-European society collaborative group was convened. 23 topics were identified, primarily from an ERS statement on lung cancer screening, and a systematic review of the literature was conducted according to ERS standards. Initial review of abstracts was completed and full text was provided to members of the group for each topic. Sections were edited and the final document approved by all members and the ERS Science Council.

RESULTS

Nine topics considered most important and frequent were reviewed as standalone topics (interstitial lung abnormalities, emphysema, bronchiectasis, consolidation, coronary calcification, aortic valve disease, mediastinal mass, mediastinal lymph nodes and thyroid abnormalities). Other topics considered of lower importance or infrequent were grouped into generic categories, suitable for general statements.

CONCLUSIONS

This European collaborative group has produced an incidental findings statement that can be followed during lung cancer screening. It will ensure that an evidence-based approach is used for reporting and managing incidental findings, which will mean that harms are minimised and any programme is as cost-effective as possible.

Lung Cancer Screening in Asbestos-Exposed Populations

Asbestos exposure is the most important cause of occupational lung cancer mortality. Two large randomized clinical trials in the U.S. and Europe conclusively demonstrate that annual low-dose chest CT (LDCT) scan screening reduces lung cancer mortality. Age and smoking are the chief risk factors tested in LDCT studies, but numerous risk prediction models that incorporate additional lung cancer risk factors have shown excellent performance. The studies of LDCT in asbestos-exposed populations shows favorable results but are variable in design and limited in size and generalizability. Outstanding questions include how to: (1) identify workers appropriate for screening, (2) organize screening programs, (3) inform and motivate people to screen, and (4) incorporate asbestos exposure into LDCT decision-making in clinical practice. Conclusion: Screening workers aged ≥50 years with a history of ≥5 years asbestos exposure (or fewer years given intense exposure) in combination with either (a) a history of smoking at least 10 pack-years with no limit on time since quitting, or (b) a history of asbestos-related fibrosis, chronic lung disease, family history of lung cancer, personal history of cancer, or exposure to multiple workplace lung carcinogens is a reasonable approach to LDCT eligibility, given current knowledge. The promotion of LDCT-based screening among asbestos-exposed workers is an urgent priority.

Asbestosis Mimicking Metastatic Lung Cancer: Case Report

The clinical diagnosis of asbestosis is primarily based on chest radiographic evidence of pleural thickening and interstitial fibrosis combined with a history of exposure to asbestos. We report herein the case of a 65-year-old man with asbestosis pathologically diagnosed after surgical lung biopsy. He had a work history including farming, cementing, and casting and was admitted with dyspnea. Chest computed tomography revealed multiple well-defined nodules in both lungs and a 4.1 cm peribronchial consolidation with fibrotic changes in the right lower lobe. We suspected metastatic lung cancer and video-assisted thoracoscopic biopsy was performed in the lung lesion of the right lower lobe. Asbestosis was confirmed following histological examination. The patient is currently completing outpatient visits without significant changes.

Screening for Occupational Lung Cancer: An Unprecedented Opportunity

Selected occupational populations are at the highest risk of lung cancer, because they smoke at increased rates and are concurrently exposed to workplace lung carcinogens. Low-dose computed tomography (CT)-based lung cancer screening has an enormous potential to reduce lung cancer mortality in these populations, as shown both in the lung cancer screening studies in the general population and in studies of workers at high risk of lung cancer. Pulmonologists can play a key role in identifying workers at high risk of lung cancer and ensuring that they are offered annual low-dose CT scans for early lung cancer detection.

ACR Appropriateness Criteria® Occupational Lung Diseases

Ordering the appropriate diagnostic imaging for occupational lung disease requires a firm understanding of the relationship between occupational exposure and expected lower respiratory track manifestation. Where particular inorganic dust exposures typically lead to nodular and interstitial lung disease, other occupational exposures may lead to isolated small airway obstruction. Certain workplace exposures, like asbestos, increase the risk of malignancy, but also produce pulmonary findings that mimic malignancy. This publication aims to delineate the common and special considerations associated with occupational lung disease to assist the ordering physician in selecting the most appropriate imaging study, while still stressing the importance of a multidisciplinary approach. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Low-dose computed tomography screening for lung cancer in people with workplace exposure to asbestos

OBJECTIVES

Smoking is the main risk factor for lung cancer, but environmental and occupational exposure to carcinogens also increase lung cancer risk. We assessed whether extending low-dose computed tomography (LDCT) screening to persons with occupational exposure to asbestos may be an effective way reducing lung cancer mortality.

MATERIALS AND METHODS

We conducted a nested case-control study within the COSMOS screening program, assessing past asbestos exposure with a questionnaire. LDCT scans of asbestos-exposed participants were reviewed to assess the presence of pulmonary, interstitial and pleural alterations in comparison to matched unexposed controls. We also performed an exhaustive review, with meta-analysis, of the literature on LDCT screening in asbestos-exposed persons.

RESULTS

Exposure to asbestos, initially self-reported by 9.8% of COSMOS participants, was confirmed in 216 of 544 assessable cases, corresponding to 2.6% of the screened population. LDCT of asbestos-exposed persons had significantly more pleural plaques, diaphragmatic pleural thickening and pleural calcifications, but similar frequency of parenchymal and interstitial alterations to unexposed persons. From 16 papers, including this study, overall lung cancer detection rates at baseline were 0.81% (95% CI 0.50-1.19) in asbestos-exposed persons, 0.94% (95% CI 0.47-1.53) in asbestos-exposed smokers (12 studies), and 0.11% (95% CI 0.00-0.43) in asbestos-exposed non-smokers (9 studies).

CONCLUSION

Persons occupationally exposed to asbestos should be monitored to gather more information about risks. Although LDCT screening is effective in the early detection lung cancer in asbestos-exposed smokers, our data suggest that screening of asbestos-exposed persons with no additional risk factors for cancer does is not viable due to the low detection rate.

Managing Incidental Findings on Thoracic CT: Mediastinal and Cardiovascular Findings. A White Paper of the ACR Incidental Findings Committee

The ACR Incidental Findings Committee presents recommendations for managing incidentally detected mediastinal and cardiovascular findings found on CT. The Chest Subcommittee was composed of thoracic radiologists who developed the provided guidance. These recommendations represent a combination of current published evidence and expert opinion and were finalized by informal iterative consensus. The recommendations address the most commonly encountered mediastinal and cardiovascular incidental findings and are not intended to be a comprehensive review of all incidental findings associated with these compartments. Our goal is to improve the quality of care by providing guidance on how to manage incidentally detected thoracic findings.

Imaging of malignant pleural mesothelioma: it is possible a screening or early diagnosis program?-a systematic review about the use of screening programs in a population of asbestos exposed workers

Malignant pleural mesothelioma (MPM) in an uncommon neoplasia with high mortality rate, mostly related to professional asbestos exposure. Clinical manifestations are not specific so that diagnosis is performed at advanced stage and screening protocols are not feasible now. On the other hand, asbestos-exposed workers have a high incidence of developing lung cancer. Low-dose computed tomography (LDCT) is a volumetric acquisition technique with high spatial resolution and a low dose exposure; it is used in many trials to detect lung tumours at an early stage in screening protocols, reducing mortality rate in smoker subjects. In recent papers, the possibly role of lung cancer screening was evaluated and recommended also in subjects exposed to asbestos. This article summarizes previous and present clinical trials validated for lung cancer screening, to discuss the possibility of early diagnosis or screening programs in a population of asbestos exposed workers by LDCT.

Coronary artery calcification is common on nongated chest computed tomography imaging

BACKGROUND

Coronary artery calcification as assessed by computed tomography (CT) is a validated predictor of cardiovascular risk, whether identified on a dedicated cardiac study or on a routine non-gated chest CT. The prevalence of incidentally detected coronary artery calcification on non-gated chest CT imaging and consistency of reporting have not been well characterized.

HYPOTHESIS

Coronary calcification is present on chest CT in some patients not taking statin therapy and may be under-reported.

METHODS

Non-gated chest CT images dated 1/1/2012 to 1/1/2013 were retrospectively reviewed. Demographics and medical history were obtained from charts. Patients with known history of coronary revascularization and/or pacemaker/defibrillator were excluded. Two independent readers with cardiac CT expertise evaluated images for the presence and anatomical distribution of any coronary calcification, blinded to all clinical information including CT reports. Original clinical CT reports were subsequently reviewed.

RESULTS

Coronary calcification was identified in 204/304 (68%) chest CTs. Patients with calcification were older and had more hyperlipidemia, smoking history, and known coronary artery disease. Of patients with calcification, 43% were on aspirin and 62% were on statin medication at the time of CT. Coronary calcification was identified in 69% of reports when present.

CONCLUSIONS

A high prevalence of coronary calcification was found in non-gated chest CT scans performed for non-cardiac indications. In one-third, coronary calcification was not mentioned in the clinical report when actually present. In this population of patients with cardiac risk factors, standard reporting of the presence of coronary calcification may provide an opportunity for risk factor modification.

Chest ultrasonography in health surveillance of asbestos-related lung diseases

Objectives:

Exposure to asbestos fibers can lead to different lung diseases, such as pleural thickening and effusion, asbestosis, mesothelioma, and lung cancer. These diseases are expected to peak in the next few years. The aim of the study was to validate ultrasonography (US) as a diagnostic tool in the management of lung diseases in subjects with a history of occupational exposure to asbestos.

Methods:

Fifty-nine retired male workers previously exposed to asbestos were enrolled in the study. Chest US was performed in all the subjects. The US operator was blinded to earlier performed computed tomography (CT) scan reports and images. The sonographic pathological findings were pleural thickening (with or without calcifications), peripheral lung consolidation, and focal sonographic interstitial syndrome and diffuse pneumogenic sonographic interstitial syndrome (pulmonary asbestosis). Significant US findings were recorded, stored, and subsequently compared with CT scans.

Results:

With some patients falling into more than one category, on CT scan, pleural thickening was reported in 33 cases (56%, 26 with calcifications), focal interstitial peripheral alterations in 23 (39%), asbestosis in 6 (10%), and peripheral lung consolidation in 13 cases (22%). Comparing each pathological condition to CT scan reports, US findings had high levels of sensitivity, specificity, positive, and negative predictive values. US did not prove effective for the detection of central lung nodules or diaphragmatic pleural thickenings. Chest US was considered to be the best technique to detect minimal pleural effusions (six subjects, 10%).

Conclusions:

Chest US might be considered an additional tool to follow up subjects occupationally exposed to asbestos who have already undergone CT scan examination and whose pathology is detectable by US as well.

Diagnostic Performance of Ultra-Low-Dose Computed Tomography for Detecting Asbestos-Related Pleuropulmonary Diseases: Prospective Study in a Screening Setting

Objective

To evaluate the diagnostic performance of Ultra-Low-Dose Chest CT (ULD CT) for the detection of any asbestos-related lesions (primary endpoint) and specific asbestos-related abnormalities, i.e. non-calcified and calcified pleural plaques, diffuse pleural thickening, asbestosis and significant lung nodules (secondary endpoints).

Material and Methods

55 male patients (55.7±8.1 years old) with occupational asbestos exposure for at least 15 years and where CT screening was indicated were prospectively included. They all underwent a standard unenhanced chest CT (120kV, automated tube current modulation), considered as the reference, and an ULD CT (135kV, 10mA), both with iterative reconstruction.

Two chest radiologists independently and blindly read the examinations, following a detailed protocol. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy and error rate of ULD CT were calculated using the exact method of Pearson with a confidence interval of 95%.

Results

Radiation dose was 17.9±1.2mGy.cm (0.25mSv) for the ULD-CT versus 288.8 ±151mGy.cm (4mSv); p <2.2e^-16.

Prevalence of abnormalities was 20%. The ULD CT’s diagnostic performance in joint reading was high for the primary endpoint (sensitivity = 90.9%, specificity = 100%, positive predictive value = 100%, negative predictive value = 97.8%), high for lung nodules, diffuse pleural thickening and calcified pleural plaques (sensitivity, specificity, PPV and NPV = 100%) and fair for asbestosis (sensitivity = 75%, specificity = 100%, PPV = 00%, NPV = 98.1%).

Intra-reader accuracy between the ULD CT and the reference CT for the primary endpoint was 98% for the senior and 100% for the junior radiologist. Inter-reader agreement for the primary endpoint was almost perfect (Cohen’s Kappa of 0.81).

Conclusion

ULD CT in the screening of asbestos exposure related diseases has 90.9% sensitivity and 100% specificity, and could therefore be proposed as a first line examination.

ACR Appropriateness Criteria Review ACR Appropriateness Criteria® Occupational Lung Diseases

Occupational lung disease is a category of disease entities characterized by a reaction of the lung parenchyma to inhaled aerosolized particles found in the environment. This document summarizes the imaging appropriateness data for silicosis, coal worker pneumoconiosis, and asbestosis. The main points of the document are that computed tomography is more sensitive than radiography, computed tomography without contrast generally suffices for evaluation, and fluorodeoxyglucose-positron emission tomography may have utility in patients with mesothelioma. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review includes an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

[Early recognition of lung cancer in workers occupationally exposed to asbestos]

Despite the fact that working with asbestos and placing it on the market have been banned in Germany since 1993 according to the Ordinance on Hazardous Substances, asbestos-related diseases of the lungs and pleura are still the leading cause of death in occupational diseases. The maximum industrial usage of asbestos was reached in former West Germany in the late 1970s and in former East Germany the late 1980s. Occupational diseases, mainly mesotheliomas and lung cancer emerging now are thus caused by asbestos exposure which occurred 30-40 years earlier. It is known that the combination of smoking and asbestos exposure results in a superadditive increase in the risk to develop lung cancer. No suitable screening methods for early detection of malignant mesothelioma are currently available and the therapeutic options are still very limited; however, the national lung screening trial (NLST) has shown for the first time that by employing low-dose computed tomography (LDCT) in heavy smokers, lung cancer mortality can be significantly reduced. According to current knowledge the resulting survival benefits far outweigh the potential risks involved in the diagnostic work-up of suspicious lesions. These results in association with the recommendations of international medical societies and organizations were pivotal as the German statutory accident insurance (DGUV) decided to provide LDCT as a special occupational medical examination for workers previously exposed to asbestos and with a particularly high risk for developing lung cancer.

CT screening for lung cancer: Frequency of enlarged adrenal glands identified in baseline and annual repeat rounds

OBJECTIVES

To determine the frequency of adrenal enlargement of participants in a CT-screening program for lung cancer and demonstrate the progression during follow-up, separately for baseline and annual repeat rounds.

MATERIALS AND METHODS

HIPAA-compliant informed consent was obtained in 4,776 participants. The adrenal gland was defined as enlarged if it measured ≥6 mm at its largest diameter. Logistic regression analyses were performed.

RESULTS

At baseline, 202 (4 %) of 4,776 participants had adrenal enlargement. Significant factors were age (OR = 1.4, 95 % CI: 1.2-1.7) and current smoker (OR = 1.8, 95 % CI: 1.3-2.4). Follow-up 7-18 months after baseline for 133 cases with adrenal enlargement <40 mm showed it decreased or was stable in 85 (64 %), and increased by <10 mm in 48 (36 %). Five (0.04 %) cases of adrenal enlargement were newly identified, none increased beyond 40 mm on follow-up. Adrenal enlargement was a significant predictor of a subsequent diagnosis of lung cancer (OR = 2.0, 95 % CI: 1.2-3.4).

CONCLUSION

Participants with adrenal enlargement <40 mm identified at baseline and on repeat screening could be reasonably assessed on subsequent annual screening. Adrenal enlargement increased with increasing pack-years of smoking. Adrenal enlargement was an independent predictor of a subsequent diagnosis of lung cancer.

KEY POINTS

• Adrenal enlargement was seen in 4 % of participants at baseline screening. • Age and currently smoking were significantly associated with adrenal enlargement. • 0.04 % of participants were newly identified with adrenal enlargement. • Annual follow-up for adrenal enlargement <40 mm was appropriate. • Adrenal enlargement was an independent predictor of a diagnosis of lung cancer.

Role of a serum-based biomarker panel in the early diagnosis of lung cancer for a cohort of high-risk patients

BACKGROUND

This study applied a combined cancer biomarker panel to clinically identify small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) in a high-risk population.

METHODS

The serum levels of 4 biomarkers (progastrin-releasing peptide [ProGRP], carcinoembryonic antigen [CEA], squamous cell carcinoma antigen [SCC], and cytokeratin 19 fragment [CYFRA21-1]) were determined in 153 patients with a high risk of lung cancer (12 with a new diagnosis of SCLC, 52 with NSCLC, and 89 without lung cancer). Information about diagnosis delays was collected through interviews of all participants.

RESULTS

Significantly higher serum levels of ProGRP (P < .0001) were found among the SCLC patients versus the rest of the population. A receiver operating characteristic curve analysis established the cutoff values of ProGRP, CEA, SCC, and CYFRA21-1 as 300 pg/mL, 7.3 ng/mL, 3 ng/mL, and 6.5 ng/mL, respectively. The sensitivity and specificity of ProGRP in diagnosing SCLC were 75% and 100%, respectively. Among the 14 lung cancer patients with a false-negative computed tomography (CT) result, the diagnostic panel detected 8 additional cancers.

CONCLUSIONS

This panel increased the diagnostic specificity for high-risk subjects (those with renal failure being excluded), and auxiliary to a CT scan, it increased the sensitivity for patients with lung cancer. These results might be applied to shorten the diagnosis delay at health care institutions in China.

Screening of miners and millers at decreasing levels of asbestos exposure: comparison of chest radiography and thin-section computed tomography

BACKGROUND

Chest radiography (CXR) is inferior to Thin-section computed tomography in the detection of asbestos related interstitial and pleural abnormalities. It remains unclear, however, whether these limitations are large enough to impair CXR´s ability in detecting the expected reduction in the frequency of these asbestos-related abnormalities (ARA) as exposure decreases.

METHODS

Clinical evaluation, CXR, Thin-section CT and spirometry were obtained in 1418 miners and millers who were exposed to progressively lower airborne concentrations of asbestos. They were separated into four groups according to the type, period and measurements of exposure and/or procedures for controlling exposure: Group I (1940-1966/tremolite and chrysotile, without measurements of exposure and procedures for controlling exposure); Group II (1967-1976/chrysotile only, without measurements of exposure and procedures for controlling exposure); Group III (1977-1980/chrysotile only, initiated measurements of exposure and procedures for controlling exposure) and Group IV (after 1981/chrysotile only, implemented measurements of exposure and a comprehensive procedures for controlling exposure).

RESULTS

In all groups, CXR suggested more frequently interstitial abnormalities and less frequently pleural plaques than observed on Thin-section CT (p<0.050). The odds for asbestosis in groups of decreasing exposure diminished to greater extent at Thin-section CT than on CXR. Lung function was reduced in subjects who had pleural plaques evident only on Thin-section CT (p<0.050). In a longitudinal evaluation of 301 subjects without interstitial and pleural abnormalities on CXR and Thin-section CT in a previous evaluation, only Thin-section CT indicated that these ARA reduced as exposure decreased.

CONCLUSIONS

CXR compared to Thin-section CT was associated with false-positives for interstitial abnormalities and false-negatives for pleural plaques, regardless of the intensity of asbestos exposure. Also, CXR led to a substantial misinformation of the effects of the progressively lower asbestos concentrations in the occurrence of asbestos-related diseases in miners and millers.

Chest CT scan screening for lung cancer in asbestos occupational exposure: a systematic review and meta-analysis

OBJECTIVE

Lung cancer is the most frequent malignant asbestos-related pathology and remains the most fatal cancer of industrialized countries. In heavy smokers, early detection of lung cancer with chest CT scan leads to a 20% mortality reduction. However, the use of CT scan screening for early detection of lung cancer in asbestos-exposed workers requires further investigation. This study aimed to determine whether CT scan screening in asbestos-exposed workers is effective in detecting asymptomatic lung cancer using a systematic review and meta-analysis.

METHODS

We reviewed all cohort studies involving chest CT scan screening in former asbestos-exposed workers. The search strategy used the following keywords: "asbestos," "lung cancer," "screening," and "occupation*" or "work." Databases were PubMed, Cochrane Library, Science Direct, and Embase.

RESULTS

Seven studies matched our inclusion criteria. Baseline screening detected 49 asymptomatic lung cancers among 5,074 asbestos-exposed workers. Of the 49 reported lung cancers, at least 18 were in the earliest stage (stage I), accessible to complete removal surgery. The prevalence of all lung cancers detected by CT scan screening in asbestos-exposed workers was 1.1% (95% CI, 0.6%-1.8%).

CONCLUSIONS

CT scan screening in asbestos-exposed workers is effective in detecting asymptomatic lung cancer. Detection of lung cancer in asbestos-exposed workers using CT scanning is at least equal to the prevalence in heavy smokers (1%; 95% CI, 0.09%-1.1%) and also shared a similar proportion of stage I diagnoses. Screening asbestos-exposed workers could reduce mortality in proportions previously observed among heavy smokers and, thus, should not be neglected, particularly for individuals combining both exposures.

Chest HRCT signs predict deaths in long-term follow-up among asbestos exposed workers

OBJECTIVES

To study associations between chest HRCT signs and subsequent deaths in long-term follow-up.

METHODS

Lung and pleural signs of 633 asbestos exposed workers (age 45-86, mean 65) screened with HRCT were recorded by using the International Classification of Occupational and Environmental Respiratory Diseases (ICOERD) system, which contains detailed instructions for use and reference images. Subsequent mortality was checked from the national register. Cox regression adjusted for covariates (age, sex, BMI, asbestos exposure, pack-years) was used to explore the relations between HRCT signs and all-cause deaths, cardiovascular and benign respiratory deaths, and deaths from neoplasms - all according to the ICD-10 diagnostic system.

RESULTS

The follow-up totalled 5271.9 person-years (mean 8.3 y/person, range .04-10.3). 119 deaths were reported. Irregular/linear opacities, honeycombing, emphysema, large opacities, visceral pleural abnormalities and bronchial wall thickening were all significantly related to all-cause deaths. Most of these signs were associated also with deaths from neoplasms and benign respiratory disease. Deaths from cardiovascular disease were predicted by emphysema and visceral pleural abnormalities.

CONCLUSIONS

Several HRCT signs predicted deaths. Careful attention should be paid on subjects with radiological signs predictive of deaths and new secondary preventive strategies developed. This calls for further focused studies among different populations.

Comparison of the ultra-low-dose Veo algorithm with the gold standard filtered back projection for detecting pulmonary asbestos-related conditions: a clinical observational study

OBJECTIVES

Radiation delivered during CT is a major concern, especially for individuals undergoing repeated screening. We aimed to compare a new ultra-low-dose algorithm called Veo with the gold standard filtered back projection (FBP) for detecting pulmonary asbestos-related conditions.

SETTING

University Hospital CHU G. Montpied, Clermont-Ferrand, France

PARTICIPANTS

Asbestos-exposed workers were recruited following referral to screening for asbestos-related conditions. Two acquisitions were performed on a 64-slice CT: the gold standard FBP followed by Veo reconstruction.

OUTCOME MEASURES

Two radiologists independently assessed asbestos-related abnormalities, pulmonary nodules, radiation doses and image quality (noise).

RESULTS

We included 27 asbestos-exposed workers (63.3±6.5 years with 11.9±9.7 years of asbestos exposure). We observed 297 pleural plaques in 20 participants (74%). All patients (100%) had pulmonary nodules, totalling 167 nodules. Detection rates did not differ for pleural plaques (Veo 87% vs FBP 97%, NS), pleural thickening (100% for both) and pulmonary nodules (80% for both). Interstitial abnormalities were depicted less frequently with Veo than FBP. False negative and false positive did not exceed 2.7%. Compared with FBP, Veo decreased the radiation dose up to 87% (Veo 0.23±0.07 vs FBP 1.83±0.88 mSv, p<0.001). The objective image noise also decreased with Veo as much as 23% and signal-to-noise ratio increased up to 33%.

CONCLUSIONS

A low-dose CT with Veo reconstruction substantially reduced radiation. Veo compared favourably with FBP in detecting pleural plaques, pleural thickening and pulmonary nodules. These results should be confirmed on a larger sample size before the use of Veo in clinical routine practice in asbestos-related conditions, especially regarding the low prevalence of interstitial abnormalities in this study.

TRIAL REGISTRATION NUMBER

NCT01955018.

Management of patients with incidental findings in imaging tests: a large prospective single-center study

We prospectively followed up patients with an incidental finding detected in an image test to assess the additional interventions carried out and the clinical implications of the incidental findings detected. Out of 474 patients with an incidental finding, 63 (13.3%) were further evaluated, and of these patients, 25 (39.7%) had clinical implications. Patients who had an X-ray (24/76, 31.6%), with a preoperative examination (19/77 24.7%), and with an incidental finding in the thoracic cavity (34/117, 29.1%) or in the head/neck (6/28, 21.4%) were more likely to have additional evaluations.

Genes involved in innate immunity associated with asbestos-related fibrotic changes

Objectives

To determine whether genetic polymorphisms in several candidate genes related to innate immunity and protease–antiprotease balance modify individual susceptibility to develop asbestos-related fibrotic pleuropulmonary changes.

Methods

Sixteen polymorphisms from nine genes (NLRP3, CARD8, TNF, TGFB1, GC, MMP1, MMP9, MMP12 and TIMP2) were genotyped from 951 Finnish asbestos-exposed workers. The genotype/haplotype data were compared to signs of fibrosis and pleural thickenings using linear and logistic regression analysis adjusted for potential confounders.

Results

A functional polymorphism (Q705K; rs35829419) in the NLRP3 gene was associated with interstitial lung fibrosis (p=0.013), and the TGFB1 rs2241718 SNP with visceral pleural fibrosis (VPF) (p=0.044). In stratified analysis, the carriage of at least one NLRP3 variant allele conferred a 2.5-fold increased risk for pathological interstitial lung fibrosis (OR 2.44, 95% CI 0.97 to 6.14). Conversely, the carriage of at least one TGFB1 rs2241718 variant allele protected against VPF (OR 0.62, 95% CI 0.39 to 0.98). The TIMP2 rs2277698 SNP and a haplotype consisting of the TGFB1 rs1800469 and rs1800470 SNPs were associated with the degree of pleural thickening calcification (p=0.037 and p=0.035), and the CARD8 rs2043211 SNP with the greatest thickness of pleural plaques (p=0.015).

Conclusions

Our results support the hypothesis that the NLRP3 inflammasome is important in the development of fibrotic lung disease by associating the NLRP3 rs35829419 variant allele with increased risk of asbestos-related interstitial lung fibrosis, and the TGFB1 rs2241718 variant allele with decreased risk of asbestos-related VPF. Polymorphisms in CARD8 and TIMP2 are proposed to modify the development and/or calcification of pleural thickenings.

Asbestos and the lung in the 21st century: an update

The asbestos-related disorders (ARDs) are currently of significant occupational and public health concern. Asbestos usage has been banned in most developed countries, but asbestos is still used in many developing countries and the number of cases of ARDs worldwide is rising. Many countries are now experiencing an epidemic of ARDs that is the legacy of occupational exposure in the 1960s-1980s because of the long latency period between asbestos exposure and manifestation of disease. It is likely that asbestos-related mortality and morbidity will continue to increase. Although the most feared complications of asbestos inhalation are the malignant conditions such as mesothelioma and lung cancer, asbestos inhalation more frequently results in benign conditions such as pleural plaques, diffuse pleural thickening, and asbestosis (pulmonary fibrosis due to asbestos exposure). Over recent years, there have been changes in the epidemiology of mesothelioma, in clinical management of ARDs and developments in new techniques for early detection of malignancy. This review provides an update on the respiratory manifestations of asbestos exposure and also considers advances in screening methods that may affect future management in the workplace.

Association of genes of protease-antiprotease balance pathway to lung function and emphysema subtypes

Background

The imbalance between proteases and antiproteases has been proposed to participate to the pathogenesis of chronic obstructive pulmonary disease (COPD) and emphysema. Gene level variation in different metalloproteinases, metalloproteinase inhibitors, and cytokines affecting them may contribute to this imbalance and destruction of the lung parenchyma. We investigated whether polymorphisms in selected protease-antiprotease balance pathway genes predispose to different emphysema subtypes (centrilobular, paraseptal, panlobular, and bullae) and airflow limitation among Finnish construction workers.

Methods

Eleven single nucleotide polymorphisms (SNPs) from seven genes (GC: rs7041 and rs4588; MMP1: rs1799750; MMP9: rs3918242; MMP12: rs652438; TIMP2: rs2277698; TNF: rs1799724 and rs1800629; TGFB1: rs1800469, rs1800470, and rs2241718) were analyzed from 951 clinically and radiologically characterized construction workers. The genotype and haplotype data was compared to different emphysematous signs confirmed with high resolution computed tomography (HRCT), forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and maximal expiratory flow at 50% of FVC (MEF50) by using linear and logistic regression analyses, adjusted for potential confounders.

Results

The TIMP2 rs2277698 SNP was associated with overall (p = 0.022) and paraseptal (p = 0.010) emphysema, as well as with FEV₁/FVC ratio (p = 0.035) and MEF50 (p = 0.008). The TGFB1 rs2241718 and MMP9 rs3918242 SNPs were associated with centrilobular emphysema (p = 0.022 and p = 0.008), and the TNF rs1800629 SNP with paraseptal emphysema (p = 0.017). In stratified analysis, individuals with at least one TIMP2 rs2277698 or TNF rs1800629 variant allele were found to be at around two-fold risk for pathological paraseptal changes (OR 1.94, 95% CI 1.14-3.30; OR 2.10, 95% CI 1.24-3.56). On the contrary, the risk for pathological centrilobular changes was halved for individuals with at least one MMP9 rs3918242 (OR 0.51, 95% CI 0.30-0.86) or TGFB1 rs2241718 (OR 0.53, 95% CI 0.30-0.90) variant allele, or TGFB1 rs1800469-rs1800470 AT-haplotype (OR 0.55, 95% CI 0.33-0.93). MEF50, in turn, was significantly reduced among individuals with at least one TIMP2 rs2277698 variant allele (p = 0.011).

Conclusion

Our findings strengthen the hypothesis of the importance of protease-antiprotease balance in pathogenesis of emphysema and shed light on the aetiology of different emphysema subtypes by associating MMP9 and TGFB1 to centrilobular emphysema, and TIMP2 and TNF to paraseptal emphysema and/or airflow obstruction.

Asbestos-related pleuropulmonary diseases: benign and malignant

Asbestos is known for its desirable properties of thermal and heat resistance along with excellent strength and durability. It was widely used in many industries since the late 19th century, until its adverse effects on health were recognized. The occurrence of pleuropulmonary changes from exposure to asbestos often has a latency period of 20 to 30 years. The use of asbestos has been banned, regulated, and minimized in many countries, but in several developing countries, the use of asbestos in industries is still a common practice. In this article, the benign and malignant clinical manifestations of asbestos exposure are discussed.

Early detection of malignant pleural mesothelioma in asbestos-exposed individuals with a noninvasive proteomics-based surveillance tool

BACKGROUND

Malignant pleural mesothelioma (MM) is an aggressive, asbestos-related pulmonary cancer that is increasing in incidence. Because diagnosis is difficult and the disease is relatively rare, most patients present at a clinically advanced stage where possibility of cure is minimal. To improve surveillance and detection of MM in the high-risk population, we completed a series of clinical studies to develop a noninvasive test for early detection.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted multi-center case-control studies in serum from 117 MM cases and 142 asbestos-exposed control individuals. Biomarker discovery, verification, and validation were performed using SOMAmer proteomic technology, which simultaneously measures over 1000 proteins in unfractionated biologic samples. Using univariate and multivariate approaches we discovered 64 candidate protein biomarkers and derived a 13-marker random forest classifier with an AUC of 0.99±0.01 in training, 0.98±0.04 in independent blinded verification and 0.95±0.04 in blinded validation studies. Sensitivity and specificity at our pre-specified decision threshold were 97%/92% in training and 90%/95% in blinded verification. This classifier accuracy was maintained in a second blinded validation set with a sensitivity/specificity of 90%/89% and combined accuracy of 92%. Sensitivity correlated with pathologic stage; 77% of Stage I, 93% of Stage II, 96% of Stage III and 96% of Stage IV cases were detected. An alternative decision threshold in the validation study yielding 98% specificity would still detect 60% of MM cases. In a paired sample set the classifier AUC of 0.99 and 91%/94% sensitivity/specificity was superior to that of mesothelin with an AUC of 0.82 and 66%/88% sensitivity/specificity. The candidate biomarker panel consists of both inflammatory and proliferative proteins, processes strongly associated with asbestos-induced malignancy.

SIGNIFICANCE

The SOMAmer biomarker panel discovered and validated in these studies provides a solid foundation for surveillance and diagnosis of MM in those at highest risk for this disease.

Chest imaging and lung function impairment after long-term occupational exposure to low concentrations of chrysotile

The aim of the present study was the investigation of radiographic findings in relation to lung function after occupational exposure to permissible levels of relatively pure chrysotile (0.5-3% amphiboles). We studied 266 out of the total 317 employees who have worked in an asbestos cement factory during the period 1968-2004 with chest x-ray, high-resolution computed tomography (HRCT) and lung function tests. Sensitivity of chest x-ray was 43% compared to HRCT. Abnormal HRCT findings were found in 75 subjects (67%) and were related to age, occupational exposure duration, and spirometric data. The presence of parenchymal or visceral pleural lesions (exclusively or as the predominant abnormality) was being accompanied by lower total lung capacity and diffusion capacity. HRCT was much more sensitive than chest x-ray for occupational chrysotile exposure. Lung function impairment was related with parenchymal but not with pleural HRCT abnormalities.

SERPINE2 haplotype as a risk factor for panlobular type of emphysema

Background

SERPINE2 (serpin peptidase inhibitor, clade E, member 2) has previously been identified as a positional candidate gene for chronic obstructive pulmonary disease (COPD) and has subsequently been associated to COPD and emphysema in several populations. We aimed to further examine the role of SERPINE2 polymorphisms in the development of pulmonary emphysema and different emphysema subtypes.

Methods

Four single nucleotide polymorphisms (SNPs) in SERPINE2 were analyzed from 951 clinically and radiologically examined Finnish construction workers. The genotype and haplotype data was compared to different emphysematous signs confirmed with high-resolution computed tomography (HRCT), forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), diffusing capacity (DL_CO), and specific diffusing capacity (DL_CO/VA).

Results

Three of the studied SERPINE2 SNPs (rs729631, rs975278, and rs6748795) were found to be in tight linkage disequilibrium. Therefore, only one of these SNPs (rs729631) was included in the subsequent analyses, in addition to the rs840088 SNP which was in moderate linkage with the other three studied SNPs. The rs729631 SNP showed a significant association with panlobular emphysema (p = 0.003). In further analysis, the variant allele of the rs729631 SNP was found to pose over two-fold risk (OR 2.22, 95% CI 1.05-4.72) for overall panlobular changes and over four-fold risk (OR 4.37, 95% CI 1.61-11.86) for pathological panlobular changes. A haplotype consisting of variant alleles of both rs729631 and rs840088 SNPs was found to pose an almost four-fold risk for overall panlobular (OR 3.72, 95% CI 1.56-8.90) and subnormal (OR 3.98, 95% CI 1.55-10.20) emphysema.

Conclusions

Our results support the previously found association between SERPINE2 polymorphisms and pulmonary emphysema. As a novel finding, our study suggests that the SERPINE2 gene may in particular be involved in the development of panlobular changes, i.e., the same type of changes that are involved in alpha-1-antitrypsin (AAT) -deficiency.

Incidental findings from lung CT scans: implications for research

INTRODUCTION

We aimed to evaluate the number and nature of incidental findings in CT chest scans in the context of a study of the pulmonary effects of cannabis.

METHODS

Three hundred fifty-seven participants were recruited: 78 cannabis-only smokers, 92 tobacco-only smokers, 106 smokers of cannabis and tobacco and 81 never smokers. All participants underwent a high-resolution CT scan of their thorax. Two radiologists read the scans. Associations between abnormalities and age, sex, tobacco and cannabis smoking status were expressed as odds ratios (OR) with 95% confidence interval.

RESULTS

Seventy-six findings requiring referral or further investigations were found in 71/357 (19.9%) of participants. In multivariate analyses, only older age, OR (per decade) 2.1 (1.4 to 3.0), was associated with a respiratory abnormality on the CT scan. A total of 37/76 (48.7%) of the abnormalities detected were extra-pulmonary, with findings observed across a wide range of organ systems. Only older age, OR (per decade) 1.7 (1.2 to 2.5), was associated with a non-respiratory abnormality.

CONCLUSION

The common occurrence of abnormal findings requiring referral or further investigations raises practical, ethical and medico-legal issues which need to be carefully considered in research programmes utilising chest CT scanning.

[What are the tools for post-occupational follow-up, how should they be performed and what are their performance, limits and benefit/risk ratio? Chest X-Ray and CT scan]

Chest radiography and computed tomography (CT) are the two radiological techniques used for the follow-up of people exposed to asbestos. Since the last conference of consensus (1999), the scientific literature has primarily covered high-resolution CT and high-resolution volume CT (HR-VCT). We consider in turn the contribution of digital thoracic radiography, recommendations for the performance of HR-VCT to ensure the quality of examination while controlling the delivered radiation dose, and the need to refer to the "CT atlas of benign diseases related to asbestos exposure", published by a group of French experts in 2007, for interpretation. The results of the published studies concerning radiography or CT are then reviewed. We note the great interobserver variability in the recognition of pleural plaques and asbestosis, indicating the need for adequate training of radiologists, and the importance of defining standardized, quantified criteria for CT abnormalities. The very low agreement between thoracic and general radiologists must be taken into account. The reading of CT scans in cases of occupational exposure to asbestos should be entrusted to thoracic radiologists or to general radiologists having validated specific training. A double interpretation of CT could be considered in medicosocial requests. CT is more sensitive than chest radiography in the detection of bronchial carcinoma but generates a great number of false positive results (96 to 99%). No scientific data are available to assess the role of imaging by either CT or chest radiography in the early detection of mesothelioma.

Occupational toxicology of asbestos-related malignancies

INTRODUCTION

Asbestos is banned in most Western countries but related malignancies are still of clinical concern because of their long latencies. This review identifies and addresses some controversial occupational and clinical aspects of asbestos-related malignancies.

METHODS

Papers published in English from 1980 to 2009 were retrieved from PubMed. A total of 307 original articles were identified and 159 were included.

ASSESSMENT OF EXPOSURE

The retrospective assessment of exposure is usually performed by using questionnaires and job exposure matrices and by careful collection of medical history. In this way crucial information about manufacturing processes and specific jobs can be obtained. In addition, fibers and asbestos bodies are counted in lung tissue, broncho-alveolar lavage, and sputum, but different techniques and interlaboratory variability hamper the interpretation of reported measurements. SCREENING FOR MALIGNANCIES: The effectiveness of low-dose chest CT screening in exposed workers is debatable. Several biomarkers have also been considered to screen individuals at risk for lung cancer and mesothelioma but reliable signatures are still missing. ATTRIBUTION OF LUNG CANCER: Exposures correlating with lung cancer are high and in the same range where asbestosis occurs. However, the unresolved question is whether the presence of fibrosis is a requirement for the attribution of lung cancer to asbestos. The etiology of lung cancer is difficult to define in cases of low-level asbestos exposure and concurrent smoking habits. MESOTHELIOMA: The diagnosis of malignant mesothelioma may also be difficult, because of procedures in sampling, fixation, and processing, and uses of immunohistochemical probes.

CONCLUSIONS

Assessment of exposure is crucial and requires accurate medical and occupational histories. Quantitative analysis of asbestos body burden is better performed in digested lung tissues by counting asbestos bodies by light microscopy and/or uncoated fibers by transmission electron microscopy. The benefits of screenings for asbestos-related malignancies are equivocal. The attribution of lung cancer to asbestos exposure is difficult in a clinical setting because of the need to assess asbestos body burden and the fact that virtually all these patients are also tobacco smokers or former smokers. Given the premise that asbestosis is necessary to causally link lung cancer to asbestos, it follows that the assessment of both lung fibrosis and asbestos body burden is necessary.

Incidental findings in imaging diagnostic tests: a systematic review

The objective of this review is to summarise the available evidence on the frequency and management of incidental findings in imaging diagnostic tests. Original articles were identified by a systematic search of the MEDLINE, EMBASE and Cochrane Library Plus databases using appropriate medical headings. Extracted variables were study design; sample size; type of imaging test; initial diagnosis; frequency and location of incidental findings; whether clinical follow-up was performed; and whether a definitive diagnosis was made. Study characteristics were assessed by one reviewer and checked by a second reviewer. Any disagreement was solved by consensus. The relationship between the frequency of incidental findings and the study characteristics was assessed using a one-way ANOVA test, as was the frequency of follow-up of incidental findings and the frequency of confirmation. 251 potentially relevant abstracts were identified and 44 articles were finally included in the review. Overall, the mean frequency of incidental findings was 23.6% (95% confidence interval (CI) 15.8-31.3%). The frequency of incidental findings was higher in studies involving CT technology (mean 31.1%, 95% CI 20.1-41.9%), in patients with an unspecific initial diagnosis (mean 30.5, 95% CI 0-81.6) and when the location of the incidental findings was unspecified (mean 33.9%, 95% CI 18.1-49.7). The mean frequency of clinical follow-up was 64.5% (95% CI 52.9-76.1%) and mean frequency of clinical confirmation was 45.6% (95% CI 32.1-59.2%). Although the optimal strategy for the management of these abnormalities is still unclear, it is essential to be aware of the low clinical confirmation in findings of moderate and major importance.

Assessing the impact of incidental findings in a lung cancer screening study by using low-dose computed tomography

PURPOSE

To assess the prevalence and nature of incidental findings (IF) seen in low-dose computed tomographies (LDCT) from a lung cancer screening study for at-risk individuals.

MATERIALS AND METHODS

Radiology reports from LDCTs of 4073 participants of a lung cancer screening study were retrospectively reviewed for findings other than lung nodules, that is, IFs, which were regarded as actionable. The frequency, nature, and expected cost of these IFs, and their anticipated follow-up were estimated.

RESULTS

There were 880 IFs described in 782 study participants (19%); the median age of the participants was 62 years (range, 46-80 years). More IFs were found in men (55%) than in women. The majority of these findings were noncardiovascular (76%), for which imaging was suggested for 74%. There were 7 severe IFs (0.8%) that merited immediate attention. Seven known cancers were diagnosed from follow-ups of the IFs. The majority of IFs (n = 486 [55%]) would require imaging follow-up if clinically indicated, with an estimated total a cost of CAN$45,500 to CAN$51,000 to provide initial diagnostic workup.

CONCLUSION

IFs on lung cancer screening studies are not uncommon and frequently require imaging or other follow-up for definitive diagnoses and to assess their clinical relevance. The implication of IFs has to be considered when determining a cost-effective and ethical protocol for the utilisation of LDCT in a high-risk population.

Current status of screening for malignant pleural mesothelioma

Malignant mesothelioma is characterized by its association with asbestos, its long latency period, and the propensity for the diagnosis to be obtained in the later stages of the disease. Because the high-risk cohorts for mesothelioma are fairly well defined by the association with asbestos, and the exposure is usually in the workplace, it is hypothesized that early detection of the disease could (1) find patients at an earlier, more treatable stage and (2) result in prolonged survival over the present median 12 months from the start of therapy. Many studies have used standard chest X-ray to characterize changes associated with asbestos-exposed individuals, but the insensitivity of X-ray in screening patients with mesothelioma has never supported the wide-scale adaptation of such an effort. With the advent of computerized tomography, prospective trials, many of which are chiefly prevalence detection studies, have been performed and stress the importance for proper detailing by carefully qualifying suspicious changes, as well as defining the correct cohort to screen. Most recently, serum biomarkers with the potential to discriminate asbestos-exposed, non-cancer-bearing individuals from those with mesothelioma have been investigated both at single institutions and with multi-institutional-blinded trials. These markers, including soluble mesothelin-related protein, osteopontin, and megakaryocyte potentiating factor, may, in the future, be incorporated into a screening algorithm for high-risk asbestos-exposed individuals to help monitor these cohorts in a noninvasive fashion and guide the use of computerized tomography.

Clinical and HRCT screening of heavily asbestos-exposed workers

PURPOSE

To characterize asbestosis today and to clarify the indications for high-resolution computed tomography (HRCT) in the surveillance of heavily exposed workers.

METHODS

Six hundred and twenty-seven workers were screened and HRCT findings were classified and divided in two groups: pulmonary fibrosis (n = 86) and no fibrosis (n = 541).

RESULTS

Most (65/86 = 76%) of the detected fibrosis cases were mild. The magnitude of asbestos exposure showed an unexpected inverse relation with fibrosis. In multivariate analyses, age, forced expiratory volume in 1 s/forced vital capacity ratio, and poor diffusing capacity were associated with HRCT fibrosis, but asbestos exposure was not.

CONCLUSIONS

Asbestosis seems to be characterized by mild fibrosis today even in heavily exposed workers. To avoid radiation exposure in HRCT, age and lung function data may be used only to a limited extent to select imaging candidates. Selection and recollection biases may distort the relation between asbestos exposure and fibrosis.