Contribution of environmental fibers to respiratory cancer

DTPA clearance test: a sensitive method for detecting radiation-induced lung fibrosis in lung cancer patients

OBJECTIVE

The aim of this study is to analyze the frequency of lung injury and the sensitivity of the diethylenetriamine penta-acetic acid (DTPA) clearance test in detecting lung injury in patients undergoing radiotherapy (RT) to the thorax.

MATERIAL AND METHOD

Twenty individuals scheduled for RT for lung cancer were included as the patient group. The healthy control group consisted of 20 age and gender-matched individuals who were nonsmokers with no history of comorbidities. We conducted follow-up with patients at 0-1-6 months, performing carbon monoxide diffusion test (DLCO), DTPA clearance test (excluding the first month), and high-resolution computed tomography of the thorax. The control group was followed up with DLCO between the baseline and 6th months.

RESULTS

Ninety percent of the patient group was male, and the median age was 62 years. Seventy percent of the patients had squamous cell carcinoma and adenocarcinoma. Pneumonitis was detected in the patient group in the first month (100%) and fibrosis in the sixth month (%100) Both at the beginning and in the sixth month, the DLCO values of patients who received RT were lower than those of the control group ( P  = 0.001 and P  < 0.001, respectively). While DTPA clearance was similar between irradiated and non-radiated lungs at the beginning, there was a substantial decrease in the irradiated lung in the sixth month( P  = 0.001). There was no significant correlation between malignancy type, RT dose, and tumor size( P  > 0.05).

CONCLUSION

The DTPA clearance test could be an alternative method for demonstrating radiation injury in patients receiving RT.

Unravelling hub genes as potential therapeutic targets in lung cancer using integrated transcriptomic meta-analysis and in silico approach

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide. Smoking has been identified as the main contributing cause of the disease's development. The study aimed to identify the key genes in small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), the two major types of LC. Meta-analysis was performed with two datasets GSE74706 and GSE149507 obtained from Gene Expression Omnibus (GEO). Both the datasets comprised samples from cancerous and adjacent non-cancerous tissues. Initially, 633 differentially expressed genes (DEGs) were identified. To understand the underlying molecular mechanism of the identified genes, pathway enrichment, gene ontology (GO) and protein-protein interaction (PPI) analyses were done. A total of 9 hub genes were identified which were subjected to mutation study analysis in LC patients using cBioPortal. These   9 genes (i.e. AURKA, AURKB, KIF23, RACGAP1, KIF2C, KIF20A, CENPE, TPX2 and PRC1) have shown overexpression in LC patients and can be explored as potential candidates for prognostic biomarkers. TPX2 reported a maximum mutation of 4 % . This was followed with high throughput screening and docking analysis to identify the potential drug candidates following competitive inhibition of the AURKA-TPX2 complex. Four compounds, CHEMBL431482, CHEMBL2263042, CHEMBL2385714, and CHEMBL1206617 were identified. The results signify that the selected 9 genes can be explored as biomarkers in disease prognosis and targeted therapy. Also, the identified 4 compounds can be further analyzed as promising therapeutic candidates.Communicated by Ramaswamy H. Sarma.

How Does Environmental and Occupational Exposure Contribute to Carcinogenesis in Genitourinary and Lung Cancers?

Environmental and occupational exposures have been associated with an increased risk of different types of cancers, although the exact mechanisms of higher carcinogenesis risk are not always well understood. Lung cancer is the leading cause of global cancer mortality, and, also, genitourinary neoplasms are among the main causes of cancer-related deaths in Western countries. The purpose of this review is to describe the main environmental and occupational factors that increase the risk of developing lung and genitourinary cancers and to investigate carcinogenesis mechanisms that link these agents to cancer onset. Further objectives are to identify methods for the prevention or the early detection of carcinogenic agents and, therefore, to reduce the risk of developing these cancers or to detect them at earlier stages.

18F-Fluoro-2-Deoxy-d-Glucose PET/Computed Tomography Evaluation of Lung Cancer in Populations with High Prevalence of Tuberculosis and Other Granulomatous Disease

Pulmonary tuberculosis infects one-third of world's population and is responsible for the high mortality and morbidity in developing countries. The presence of a high number of macrophages and lymphocytes in active tuberculosis granulomas is associated with high uptake of ¹⁸F-fluoro-2-deoxy-d-glucose on PET imaging mimicking lung cancer. In many cases, radiological features of pulmonary tuberculosis are undistinguishable from lung cancer, which makes the diagnosis difficult. Clinical history and computed tomographic (CT) findings on a hybrid PET/CT are as important as findings on a PET in the diagnosis of lung cancer.

Plastic and Human Health: A Micro Issue?

Microplastics are a pollutant of environmental concern. Their presence in food destined for human consumption and in air samples has been reported. Thus, microplastic exposure via diet or inhalation could occur, the human health effects of which are unknown. The current review article draws upon cross-disciplinary scientific literature to discuss and evaluate the potential human health impacts of microplastics and outlines urgent areas for future research. Key literature up to September 2016 relating to accumulation, particle toxicity, and chemical and microbial contaminants was critically examined. Although microplastics and human health is an emerging field, complementary existing fields indicate potential particle, chemical and microbial hazards. If inhaled or ingested, microplastics may accumulate and exert localized particle toxicity by inducing or enhancing an immune response. Chemical toxicity could occur due to the localized leaching of component monomers, endogenous additives, and adsorbed environmental pollutants. Chronic exposure is anticipated to be of greater concern due to the accumulative effect that could occur. This is expected to be dose-dependent, and a robust evidence-base of exposure levels is currently lacking. Although there is potential for microplastics to impact human health, assessing current exposure levels and burdens is key. This information will guide future research into the potential mechanisms of toxicity and hence therein possible health effects.

Investigating palygorskite's role in the development of mesothelioma in southern Nevada: Insights into fiber-induced carcinogenicity

Similar to asbestos fibers, nonregulated mineral fibers can cause malignant mesothelioma (MM). Recently, increased proportions of women and young individuals with MM were identified in southern Nevada, suggesting that environmental exposure to carcinogenic fibers was causing the development of MM. Palygorskite, a fibrous silicate mineral with a history of possible carcinogenicity, is abundant in southern Nevada. In this study, our aim was to determine whether palygorskite was contributing to the development of MM in southern Nevada. While palygorskite, in vitro, displayed some cytotoxicity toward primary human mesothelial (HM) cells and reduced their viability, the effects were roughly half of those observed when using similar amounts of crocidolite asbestos. No Balb/c (0/19) or MexTAg (0/18) mice injected with palygorskite developed MM, while 3/16 Balb/c and 13/14 MexTAg mice injected with crocidolite did. Lack of MM development was associated with a decreased acute inflammatory response, as injection of palygorskite resulted in lower percentages of macrophages (p = .006) and neutrophils (p = .02) in the peritoneal cavity 3 d after exposure compared to injection of crocidolite. Additionally, compared to mice injected with crocidolite, palygorskite-injected mice had lower percentages of M2 (tumor-promoting) macrophages (p = .008) in their peritoneal cavities when exposed to fiber for several weeks. Our study indicates that palygorskite found in the environment in southern Nevada does not cause MM in mice, seemingly because palygorskite, in vivo, fails to elicit inflammation that is associated with MM development. Therefore, palygorskite is not a likely contributor to the MM cases observed in southern Nevada.

The ticking time-bomb of asbestos: its insidious role in the development of malignant mesothelioma

The relationship between asbestos exposure and malignant mesothelioma (MM) has been well established. Despite bans on asbestos use in an increasing number of nations, the prolonged latency from exposure to diagnosis, and the ongoing presence and use of these dangerous fibres, have led to the increasing prevalence of this deadly disease worldwide. Whilst occupational contact has been implicated in the bulk of diagnosed cases over the past 50 years, a significant proportion of disease has been linked to para-occupational, domestic and environmental exposure. In this review, we will provide an update on the impact of historical and ongoing asbestos contact in both occupational and non-occupational settings. Furthermore, we will address the unresolved controversies surrounding the use of chrysotile asbestos, the effect of gender and genetics on development of this disease, childhood mesothelioma and co-aetiological factors including SV40 exposure.

Lung Cancer Mortality and Occupational Exposure to Asbestos Among Telephone Linemen: A Historical Cohort Study in France

OBJECTIVE

The authors studied the mortality by lung cancer in telephone linemen exposed to asbestos at low levels during installation of telephone cables.

METHODS

Three hundred eight lung cancers deaths were identified in the cohort. Exposure to asbestos and to other occupational carcinogens was assessed using a job-exposure matrix.

RESULTS

The relative risk for lung cancer death associated with an estimated exposure of approximately 2 f/cc-years was 2.1 (95% confidence interval = 1.1-4.0) as compared with workers exposed to less than 0.5 f/cc-years. Mean annual exposure or exposure duration were not clearly related to lung cancer. Adjustment for other occupational lung carcinogens did not change this finding.

CONCLUSION

The observed mortality by lung cancer associated with asbestos exposure at low levels is higher than the prediction based on linear downward extrapolations from highly exposed occupational cohorts.

Asbestos fiber length as related to potential pathogenicity: a critical review

BACKGROUND

Asbestos inhalation is recognized as an exposure that increases the risk for the development of lung disease. It is unique among dusts in that it is both a carcinogen and capable of inducing extrapulmonary responses such as pleural thickening and fibrosis as well as malignancy. One feature of asbestos suggested as crucial in its pathological activity is its fibrous morphology. Long fibers that have been inhaled are cleared less readily and are thus more persistent in the body. Furthermore certain experimental models link fiber length to levels of risks for development of certain diseases. The present review will survey the data on this subject.

METHODS

The review considers experimental models that have been used to assess the response to various lengths of fibers in animal models in addition to data obtained from studies of human materials. The review also emphasizes the importance in defining the method by which a sample is categorized.

RESULTS

Data are offered which support the potential for longer fibers as well as shorter fibers to contribute to pathological responses.

CONCLUSIONS

The data presented argue that asbestos fibers of all lengths induce pathological responses and that caution should be exerted when attempting to exclude any population of inhaled fibers, based on their length, from being contributors to the potential for development of asbestos-related diseases.

The inherited nature of lung cancer: a pilot study

The role of both primary and secondary cigarette smoke exposure in the causation of lung cancer appears certain. An estimated 90% of lung cancer is attributed to cigarette smoke. Remarkably, however, less then 20% of cigarette smokers develop lung cancer. Investigators have suggested that a genetic predisposition to lung cancer may contribute to familial aggregation of this cancer. To understand the contribution of familial aggregation to this type of cancer and potentially identify individuals and families, which may be important in identifying gene(s) responsible for lung cancer, we developed criteria for identification of high-risk families. We have tested the feasibility and utility of these criteria at three Denver, CO hospitals with very different patient populations. Four hundred eighteen individuals were diagnosed with lung cancer at these three hospitals between 1/1/95 and 8/31/95. Twenty-nine percent of individuals expired prior to the time of initial contact. Family history data were obtained on 182 individuals. To be considered positive (suggesting possible autosomal dominant inheritance of lung cancer), families must have at least two first-degree relatives with lung cancer, one of which must be diagnosed before the age of 55. Seventeen of 182 (9.3%) families in the study population met these criteria. We reviewed the remaining family histories that did not meet the established criteria and identified another 2.3% (5/182) of families had evidence for autosomal dominant transmission of lung cancer. An additional 15% (23/182) of families had histories which could not be classified without further information. This study suggests that at least 11.6% of individuals diagnosed with lung cancer will have a positive family history of lung cancer. Use of the criteria developed for this study may lead to an underestimation of the inherited etiology of lung cancer.

Lung cancer mortality in a cohort of older pulp and paper workers

The occurrence of deaths due to lung cancer was studied among 883 white male workers from a pulp and paper company in northern New Hampshire. All subjects had participated in a longitudinal study of respiratory morbidity, and data from interviews were used to construct lifetime cigarette smoking and occupational histories. Most of the subjects had entered follow-up in the 1960s and, at that time, their mean age was 51 years and they had worked for the pulp and paper company a mean of 25 years. By the end of follow-up in 1992, the 512 deceased subjects included 35 whose underlying cause of death had been lung cancer. With an internal comparison using the Cox proportional-hazards model, the hazard ratio for sulfite pulp mill work was 2.5 (95% CI 1.3-4.9), while controlling for the effects of age, cigarette smoking, and work in other parts of the pulping operation. In addition, the hazard ratio for the combination of >35 pack-years of smoking and >10 years sulfite mill work was greater than the product of the hazard ratios for each factor alone. While these findings are consistent with past asbestos exposure in the sulfite pulp mill environment, the absence of mesothelioma cases is inconsistent with this type of exposure.

The etiology of lung cancer

The association between tobacco smoking and lung cancer has been noted for more than 50 years and continues to dominate the etiologic milieu of this malignant disease. Other agents, many discovered in the occupational setting, have also been substantiated as lung carcinogens. Inherent predisposition to the disease has long been suspected, and recent investigations suggest several potential mechanisms and a possible mode of inheritance. Considerable progress has been made in deciphiring the molecular defects present in lung cancer cells. These recent findings have been incorporated into two well-known models of lung carcinogenesis. As the details of the carcinogenic process are unraveled, one goal is to identify intermediate (preneoplastic) markers of exposure and inherent predisposition that will help assess the risk of lung cancer for individuals as well as for groups.

The health consequences of smoking. Cancer

Smoking has now been identified as a definite cause of cancer at many sites (Table 2). Of all cancers in the United States, 30% could be prevented if cigarette smoking were eliminated. Organs in direct contact with smoke--the oral cavity, esophagus, lung, and bronchus--are at the greatest risk of malignancy among smokers. As many as 90% of these cancers are attributable to smoking. Organs and tissues distant from smoke are also at some increased risk. Among smokers, rates of cancer of the cervix, pancreas, bladder, kidney, stomach, and hematopoietic tissue are increased 50% to 200% over rates in nonsmokers. Risk of cancer at all sites increases with increasing exposure to cigarette smoke. Cigarette smoke contains potent carcinogens that influence carcinogenesis at both early and late stages. These carcinogens can interact with other exposures, such as alcohol, to synergistically increase the risk of cancer. The adverse carcinogenic effects of cigarette smoking, however, can be reduced for all smokers if tobacco use is stopped. The prevalence of smoking among the US population as a whole has declined from 40% in 1965 to 29% in 1987. This progress against the epidemic of tobacco use has already produced a decrease in the occurrence of the most common tumor among men, lung cancer. Unfortunately, the decline in smoking prevalence and cancer incidence has not occurred equally across US populations. Death rates of lung cancer in women continue to rise, and, based upon current smoking patterns, these rates will continue to increase into the next century. The challenge to physicians and public health workers is compelling and immediate: Abstaining from smoking is the single most effective way to reduce an individual's risk of cancer.

Present and past smoking history and other predisposing factors in 100 lung cancer patients

This study assessed the accuracy of obtaining smoking history, relationships between smoking and the histologic subtypes of lung cancer, past and present smoking history, and co-carcinogen history in 100 patients seen between 1982 and 1989. A standard questionnaire filled out by the patients, a data base filled out by the physician, and medical records were abstracted, and detailed information on smoking and co-carcinogen history was obtained. Eleven percent of the patients were nonsmokers and another 41 percent were former smokers who had quit smoking more than one year prior to the diagnosis of lung cancer. Mean ages at onset and cessation of smoking and diagnosis were 17, 59, and 62 years, respectively. The histologic subtypes were as follows: adenocarcinoma, 34; squamous, 18; small cell, 24; adenosquamous, nine; large cell, nine; and bronchioloalveolar carcinoma, six. Mean pack-years of cigarette smoking for the subtypes were as follows: squamous, 82; small cell, 78; large cell, 72; adenocarcinoma, 65; adenosquamous, 48; and bronchioloalveolar carcinoma, 41. The patient and physician questionnaires had comparable data on smoking status in continued smokers and never smokers. Many former smokers filled out the patient questionnaire as a nonsmoker, but on query by the physician admitted to smoking in the past. The physician data set was more accurate in former smokers than questionnaires completed by the patients. Patients with squamous and small cell carcinomas were heavier smokers than patients with adenosquamous and bronchioloalveolar carcinomas. About 50 percent were active smokers until the diagnosis of lung cancer, but only 18 percent of patients continued to smoke after the diagnosis. About 10 percent were never smokers and about 40 percent were former smokers. Most former smokers quit smoking less than five years antecedent to the diagnosis of lung cancer.

Alveolar fiber load in asbestos workers and in subjects with no occupational asbestos exposure: an electron microscopy study

The alveolar fiber load was evaluated by bronchoalveolar lavage and by scanning and transmission electron microscopy (SEM and TEM) in 50 subjects with or without occupational exposure to asbestos. The concentration of asbestos fibers in bronchoalveolar lavage was significantly higher in the groups of people currently and formerly occupationally exposed, compared to the concentration found in people only exposed environmentally, despite wide interindividual variation within the groups. Nonasbestos inorganic fibers were present in all groups, but the concentrations did not differ significantly. Both in people occupationally exposed and in those only environmentally exposed, the alveolar load consisted mainly of ultrashort and ultrathin fibers, which can be studied only with TEM. In fact, the percentage of fibers greater than 5 micron long was only around 15% in the occupationally exposed and was minimal in those only environmentally exposed. The geometric mean diameters of asbestos fibers retained in the alveoli ranged from 0.05 micron for chrysotile to 0.15 micron for amphiboles.