The etiology of lung cancer

Cross-disease analysis identified novel common genes for both lung adenocarcinoma and lung squamous cell carcinoma

Lung squamous cell carcinoma (LSCC) exhibits a number of similarities with lung adenocarcinoma (LA) in terms of copy number alterations. However, compared with LA, the range of genetic alterations in LSCC is less understood. In the present study, a large-scale literature-based search of LA-associated genes and LSCC-associated genes was performed to identify the genetic basis in common with these two diseases. For each of the LA-associated genes, a mega-analysis was performed to test its expression variations in LSCC using 11 RNA expression datasets, with significant genes identified using statistical analysis. Subsequently, a functional pathway analysis was performed to identify a possible association between any of the significant genes identified from the mega-analysis and LSCC, followed by a co-expression analysis. A multiple linear regression (MLR) model was employed to investigate the possible influence of sample size, country of origin and study date on gene expression in patients with LSCC. Disease-gene association data analysis identified 1,178 genes involved in LA, 334 in LSCC, with a significant overlap of 187 genes (P<1.02×⁻¹⁶¹). Mega-analysis revealed that three LA-associated genes, such as solute carrier family 2 member 1 (SLC2A1), endothelial PAS domain protein 1 (EPAS1) and cyclin-dependent kinase 4 (CDK4), were significantly associated with LSCC (P<1.60×10⁻⁸), with multiple potential pathways identified by functional pathway analysis, which were further validated by co-expression analysis. The present MLR analysis suggested that the country of origin was a significant factor for the levels of expression of all three genes in patients with LSCC (P<4.0×10⁻³). Collectively, the present results suggested that genes associated with LA should be further investigated for their association with LSCC. In addition, SLC2A1, EPAS1 and CDK4 may be novel risk genes associated with LA and LSCC.

On-site Basic Health Screening and Brief Health Counseling of Chronic Medical Conditions for Veterans in Methadone Maintenance Treatment

BACKGROUND: In order to improve the delivery of health services for chronic medical conditions in our methadone clinic, we added an onsite health screening and brief health counseling to the treatment plans for patients receiving methadone maintenance treatment at the Atlanta Veterans Affairs Medical Center (VAMC). We then conducted a follow up retrospective chart review to assess whether this intervention improved health outcome for those patients. METHODS: We reviewed the charts of one hundred and two patients who received treatment at Atlanta VAMC methadone clinic between 2002 and 2008. We sought to determine whether our increased health education and screening intervention was associated with improved: 1) Improved drug addiction outcome (as measured by comparing percentage of opiate and cocaine positive drug screens from admission to most recent). 2) Basic health screening, (as measured by the patient's compliance with primary care physicians (PCP) appointments and current smoking status). 3) Management of co-occurring medical conditions (as measured by levels of LDL cholesterol, hemoglobin A1c, and systolic blood pressure (SBP). 4) Presence of QTc prolongation (difference in QTc between baseline and most recent EKG). RESULTS: Illicit drug use (opiate and cocaine) markedly decreased in patients overall. The effect was more robust for those successfully "retained" (n=55, p<0.0001) in treatment, compared to those who "dropped out" (n=40, p=0.05) of treatment. Compliance with PCP appointments was high (82% and 88% before and after the onsite intervention, respectively) for "retained" patients. LDL cholesterol level was within normal range for all patients. A1c improved by 40% after the onsite intervention as reflected by the decreased percentage of patients with A1c > 7 % from before to after the intervention (90% vs. 50%, p=0.05). However, the prevalence of uncontrolled hypertension did not significantly improve after the onsite intervention (38% vs. 28%, p=0.34). As might be expected with MMT, the prevalence of QTc prolongation actually increased from 399 m sec. (+/- 92) to 439 msec. (+/- 22) after the onsite intervention (p=0.003). CONCLUSIONS: Our retrospective study supports the previous literature that methadone maintenance therapy is effective in reducing illicit drug use. Although patients with history of heroin dependence and in methadone maintenance treatment are at increased risk for chronic medical conditions like hepatitis C and diabetes, there are minimal federal guidelines for medical care, except than a physical exam upon admission, and basic screening for some infectious diseases e.g. HIV and Hepatitis C for those patients. Our study demonstrated the need for and potential benefit of enhancing the delivery of health promotion services for chronic medical conditions in methadone maintained patients. Improving management of hepatitis C, diabetes, hypertension, and other related conditions, in this high risk, difficult-to-treat, and underserved population may reduce their morbidity and premature mortality.

Benefits of retention in methadone maintenance and chronic medical conditions as risk factors for premature death among older heroin addicts

BACKGROUND

Methadone maintenance treatment reduces rates of premature mortality in heroin addicts. However, few published studies have addressed the effectiveness of treatment, mortality rates, or causes of death in older (geriatric) patients maintained on methadone. Identifying risk factors for premature mortality and potential targets for early intervention may reduce rates of premature mortality in older patients maintained on methadone.

METHODS

We conducted a retrospective chart review for patients enrolled in the methadone maintenance program at the Atlanta Veterans Affairs Medical Center. We reviewed the charts of 91 patients and collected the following information: demographics (age, gender, marital status, and race); composite score at admission on the Addiction Severity Index (ASI); most recent ASI score for alcohol use, drug use, and medical, psychiatric, family, legal, and employment problems; results of urine drug screens for opiates, cocaine, and benzodiazepines (first 4 screens after admission and last 4 screens); dose and duration of methadone treatment; HIV and hepatitis B and C status; tobacco smoking; presence of diabetes mellitus, hypertension, heart disease, chronic obstructive pulmonary disease, or cancer; history of intravenous drug use; and missed primary care appointments (last five appointments).

RESULTS

A statistically significant association was found between diabetes mellitus and between liver and gastrointestinal cancer and premature mortality in this sample of older patients maintained on methadone (OR=30.79, p=0.008 for diabetes mellitus; OR=19.91, p=0.017 for cancer). Patients who remained in treatment showed statistically significant improvement in ASI scores for problems related to drug use and for psychiatric, medical, and legal problems. They showed a nonsignificant trend toward reduction of problems associated with alcohol use. The group of patients who dropped out of methadone treatment did not show statistically significant improvement on any area of the ASI except family problems. The group who remained in treatment also showed a statistically significant reduction in drug use when results of the first four and last four urine drug screens for opiates, cocaine, and benzodiazepines were compared (p<0.0001 for opiates and cocaine, p=0.02 for benzodiazepines).On the other hand, the group who dropped out of methadone treatment did not show any statistically significant reduction in drug use based on urine screens (p=0.05 for opiates, p=0.38 for cocaine, and p=0.53 for benzodiazepines).

CONCLUSIONS

The results presented here suggest potential targets for intervention related to lifestyle risk factors and comorbid medical conditions, such as nicotine dependence and diabetes mellitus, that may have the potential to improve health outcomes for older patients with opioid dependence.

The relation of cigarette smoking to incident Alzheimer's disease in a biracial urban community population

The relationship between smoking status and incident Alzheimer's disease (AD) was investigated in a random stratified sample of a biracial community in Chicago. Analyses are based on 1,064 persons (of 1,134 evaluated) who had data on smoking status, disease incidence, and key covariates such as apolipoprotein allele status. During a mean of about 4 years of follow-up, 170 persons met criteria for incident AD. Current smoking was associated with increased risk of incident AD (OR = 3.4, 95% CI = 1.4-8.0) compared to persons who never smoked. There was no apparent increase in risk of AD for former smokers compared to persons who never smoked (OR = 0.9, 95% CI = 0.5-1.7). Apolipoprotein E allele status modified this association in that former smokers with a upsilon4 allele were less likely to develop AD (p = 0.04) than those who never smoked. Former smokers also appeared to have a reduced risk of developing AD as their pack-years of smoking increased (p = 0.02)such that the odds of developing AD increased by 50% for every 10 years of smoking cessation (OR = 1.3, CI = 0.9-1.7). The results suggest that older people who currently smoke are more likely to develop AD compared to those who never smoked; the relation between those who used to smoke but quit and the risk of AD is complex and requires further research.

DNA methylation as a cancer-specific biomarker: from molecules to populations

Cancer contributes to a large proportion of the mortality and morbidity in the United States and worldwide. Despite advances in diagnosis and treatment of various cancers, early detection and treatment of cancer remain a challenge. Diagnosis of cancer often occurs once the disease has progressed to a point where currently available intervention options provide limited success. Therefore, techniques that enable early detection followed by targeted interventions would influence stage at diagnosis and, in turn, mortality associated with cancer. Identification of molecular biomarkers, especially those that are associated with cancer initiation and progression, shows promise as an effective strategy in this regard. One potential early detection biomarker is DNA methylation of the promoter region of certain cancer-associated genes, which results in gene inactivation. Examination of serum for circulating tumor DNA with abnormal methylation patterns offers a possible method for early detection of several cancers and serves as a point for early intervention and prevention strategies. Additionally, it is imperative to consider how such a screening mechanism can be implemented in populations at risk, especially in resource-poor settings. Thus, the challenge is to validate DNA methylation as a cancer-specific biomarker, with the ultimate goal of designing a research plan that integrates the current knowledge base regarding cancer detection and diagnosis into specific prevention and intervention strategies that can be applied at a population level.

Epidemiology of lung cancer

This review article presents lung cancer epidemiology, describing main epidemiologic characteristics including epidemiological situation in cancer incidence, mortality and survival in Europe in comparison with situation in the Czech Republic. Influence of environmental and life style risk factors like smoking, passive smoking, risk factors of work environment, ionizing radiation, air pollution, nutrition and genetic and hormonal factors are discussed.

Expression of metallothionein in lung carcinoma: correlation with histological type and grade

AIMS

Over-expression of cellular metallothionein occurs frequently in human tumours but the underlying mechanism remains unknown. The aim of this study was to assess metallothionein expression in cases of lung carcinoma and to correlate it with histopathological parameters.

METHODS AND RESULTS

Tumour tissue samples from 89 patients with lung carcinoma were immunostained by the streptavidin-biotin-peroxidase technique, using a monoclonal antibody against both metallothionein-1 and -2 isoforms. Positive matallothionein immunostaining was prominent in 44 out of 89 (49%) and negative in 45 out of 89 (51%) cases of lung carcinoma examined. Metallothionein positivity was prominent in 32 out of 43 (74%) cases of squamous cell lung carcinoma, and in 12 out of 35 (34%) cases of adenocarcinoma, while it was negative in all 11 cases of small-cell lung carcinoma examined, presenting a statistically significant difference between the different histological types. The intensity of metallothionein staining revealed a statistically significant difference between the squamous cell and adenocarcinoma cases examined. The pattern and extent of metallothionein staining in tumour cells and the expression of metallothionein in stromal cells were not correlated with histopathological parameters (type and grade) in metallothionein-positive cases of lung carcinoma examined. No association was found between metallothionein expression and lymph node status in the examined cases of lung carcinoma.

CONCLUSIONS

Our findings indicate that expression of metallothionein was evident in squamous cell lung carcinoma and adenocarcinoma, but absent in small-cell lung carcinoma, supporting evidence for participation of this protein in the biological mechanisms underlying the carcinogenic evolution in the lung.

Altered DNA repair capacity and bleomycin sensitivity as risk markers for non-small cell lung cancer

DNA repair capacity in human peripheral blood lymphocytes was monitored by the repair rate of bleomycin-induced DNA damage using an alkaline single-cell gel electrophoresis assay (comet assay). DNA repair capacity, after 15 min repair time, in lymphocytes of non-small cell lung cancer patients (n = 160) and controls (n = 180) was 67% and 79.3%, respectively (p < 0.0004). Bleomycin sensitivity defined as the tail moment of bleomycin-treated peripheral blood lymphocytes, without allowing time for DNA repair, was significantly higher in lung cancer patients than in tumor-free hospital controls (p < 0.0001). There was no correlation, in either patient or control group, between the bleomycin sensitivity and DNA repair capacity with age or gender. The median values of DNA repair capacity and sensitivity in controls were used as the cut-off points for calculating odds ratios (OR). After adjustment for age, gender and smoking status, the cases vs. controls had reduced DNA repair capacity (OR = 2.1; 95% confidence limit [CL] 1.1-4.0) and increased bleomycin sensitivity (OR = 4; 95% CL 2.2-7.4). For current smokers, the adjusted risk associated with bleomycin sensitivity was 2.3 (95% CL 1.1-4.9). We conclude that our standard comet assay as a phenotypical repair test has sufficient sensitivity and rapidity allowing application to both native and cryopreserved lymphocytes. Bleomycin sensitivity and DNA repair capacity were found to be 2 independent susceptibility markers for non-small cell lung cancer, confirming similar investigations with different marker end points. The latter were much more time consuming than the method used in our study. Thus, the comet assay is more suitable for screening large numbers of individuals in epidemiological studies. Validation of this assay in large prospective studies for the identification of subjects at high risk for non-small cell lung cancer is now warranted.

Benzo[a]pyrene diol-epoxide DNA adducts and levels of polycyclic aromatic hydrocarbons in autoptic samples from human lungs

Benzo[a]pyrene (BaP) and other polycyclic aromatic hydrocarbons (PAHs) which are present in cigarette smoke, are common air and food genotoxic contaminants and possible human carcinogens. We measured the following PAH levels: benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, BaP, dibenzo[a,h]anthracene, benzo[g,h,i]perylene as well as (+/-) syn and anti BaP diol-epoxide (BPDE) DNA adducts in autopsy samples from the lungs of non-smokers, ex-smokers and smokers who had lived in Florence, Italy. PAH levels in lung tissue were similar in all groups, with the exception of dibenzo[a,h]anthracene (DBA), which was higher in lung samples from smokers (n = 10, 0.18+/-0.17 ng/g d.w, mean +/- S.D.) compared to non-smokers (n = 15, 0.046+/-0.025 ng/g d.w) (P < 0.05), whereas ex-smokers (n = 5), had intermediate levels (0.07+/-0.03 ng/g d.w). The average level of total BPDE-DNA adducts was 4.46+/-5.76 per 10(8) bases in smokers, 4.04+/-2.37 per 10(8) in ex-smokers and 1.76+/-1.69 per 10(8) in non-smokers. The levels of non-smokers were significantly different (P < 0.05) from the levels of the smokers and ex-smokers combined. Total BPDE-DNA adducts were correlated with BaP levels in the lung samples in which both determinations were obtained (r = 0.63). Our results demonstrate that the biological load of PAHs due to environmental pollution is similar in individuals who smoke and those who do not, but BPDE-DNA adducts are higher in smokers and ex-smokers compared to non-smokers. This study further confirms the usefulness of BPDE-DNA adduct levels determination in the lungs from autopsy samples for monitoring long-term human exposure to BaP, a representative PAH.

United States lung carcinoma incidence trends: declining for most histologic types among males, increasing among females

BACKGROUND

Lung carcinoma is now the most frequently diagnosed major cancer in the world and is also the most common cause of cancer deaths in males and females in the United States and worldwide. Based on trends in cigarette smoking and on analysis of lung cancer rates by birth cohort, it was predicted that a decline would occur in age-adjusted lung cancer rates, initially in males, and approximately 10 years later in females. We evaluated age-adjusted lung cancer incidence rates for changes in trends by race, sex and histologic type to determine if and when rates may have started declining.

METHODS

We analyzed population-based incidence data from the National Cancer Institute's Third National Cancer Survey conducted between 1969 and 1971 and from the Surveillance, Epidemiology and End-results (SEER) program conducted between 1974 and 1991. Age-adjusted rates were plotted by time period using a logarithmic scale for the ordinate. We used regression methods for grouped time-to-response data to fit a model to the disease rate for age, and calendar year to estimate the calendar year of maximum disease rate.

RESULTS

During this period, the overall age-adjusted lung cancer incidence rate rose from 37.8 to 68.2 per 100,000. Lung cancer rates in both white and black males climaxed around 1984 and declined subsequently. Furthermore, among white and black males, the rates of squamous cell carcinoma, small cell carcinoma, and large cell carcinoma declined after peaks in 1981 and 1982, 1986 and 1987, and 1986 and 1988, respectively. The rates for adenocarcinoma in black males peaked in 1987 whereas the rates in white males appeared to have plateaued between 1989 and 1991. Total lung cancer rates in males exceeded those in females, with rates in black males exceeding rates in white males. Age-adjusted lung carcinoma rates among white and black females continued to increase for all histologic types with the exception of large cell carcinoma among whites, bronchioloalveolar carcinoma among whites and blacks, and adenosquamous carcinoma among blacks.

CONCLUSIONS

The cumulative effect of these trends has resulted in a plateau of total lung carcinoma incidence in all persons combined, and a decline might be expected soon, as has already been observed among males. Most of these changes reflect past cigarette smoking patterns. Demonstration of declines and tapering increases among several population subgroups suggests impending reductions in the incidence and mortality rate for this highly fatal cancer.

The National Cancer Data Base report on lung cancer

BACKGROUND

Previous Commission on Cancer data from the National Cancer Data Base (NCDB) have examined time trends in stage of disease, treatment patterns, and survival for selected cancers. The most current (1992) data for lung cancer are described here.

METHODS

Four Calls for Data have yielded a total of 560,455 lung cancer cases diagnosed in 1986-1987 and 599,597 cancer cases diagnosed in 1992, from hospital cancer registries across the United States.

RESULTS

A total of 91,115 lung cancer cases diagnosed in 1986-1987 and 92,182 diagnosed in 1992 were reported from cancer registries across the United States. Lung cancer occurs mainly in patients between the ages of 50 and 80 years. There was an increasing relative frequency of adenocarcinoma, and of lung cancer in women, and a noteworthy poor prognosis among African Americans. Lung cancer patients were reported from all types and sizes of hospitals in America, from smaller community hospitals to major teaching centers. Treatment by surgical resection occurred more frequently in the major cancer centers. The overall prognosis for lung cancer remains extremely poor.

CONCLUSIONS

For a selective category of patients (Stage I), cancer-directed surgery offers reasonable cure rates, but these data underline the need for earlier diagnosis and improved treatment modalities in the overall management of lung cancer patients.

Patterns of cigarette sales and lung cancer mortality in some central and eastern European countries, 1960-1989

BACKGROUND

Remarkable increases in lung cancer risk recently have been observed in the Central and Eastern European (CEE) area. This study examines the patterns of lung cancer mortality rates and cigarette sales in 1960-1989 in seven CEE countries with a total population of 97.5 million and 43,000 deaths from lung cancer in the last year under study.

METHODS

Trends in cigarette sales and mortality rates from lung cancer in seven CEE countries were compared for the years 1960-1989.

RESULTS

Among males, recent lung cancer death rates were the highest in Europe, and trends by country largely reflected the varied prevalence and duration of smoking in previous decades. For females, lung cancer mortality rates were much lower, although there were exponential rate increases. In the more recent birth cohorts, there were some declines in mortality rates among males, but not among females.

CONCLUSIONS

The rising cigarette consumption through the 1960s, 1970s, and, in some countries, the 1980s is accompanied in most of the countries by rising lung cancer mortality rates for young adults. This increasing cigarette consumption will determine future trends in lung cancer, which will increase well beyond the turn of the century and will continue longer for females than for males. This outlook underlines the urgent need for comprehensive lung cancer prevention with the concerted control of smoking as a priority. The role of cofactors and their interaction with smoking deserve further exploration.