Association between lymph node silicosis and lung silicosis in 4,384 German uranium miners with lung cancer.

This study investigates the association between lymph node-only and lung silicosis in uranium miners with lung cancer and exposure to quartz dust. Tissue slides of 4,384 German uranium miners with lung cancer were retrieved from an autopsy archive and reviewed by 3 pathologists regarding silicosis in the lungs and lymph nodes. Cumulative exposure to quartz dust was assessed with a quantitative job-exposure matrix. The occurrence of silicosis by site was investigated with regression models for exposure to quartz dust. Miners with lung silicosis had highest cumulative quartz exposure, followed by lymph node-only silicosis and no silicosis. At a cumulative quartz exposure of 40 mg/m(3) × years, the probability of lung silicosis was above 90% and the likelihood of lymph node-only silicosis and no silicosis do not differ anymore. The results support that lymph node silicosis can precede lung silicosis, at least in a proportion of subjects developing silicosis, and that lung silicosis strongly depends on the cumulative quartz dose.

Major histopathological patterns of lung cancer related to arsenic exposure in German uranium miners.

OBJECTIVE: The mechanisms of action of arsenic in the development of lung cancer are still not yet elucidated. Considering the relationship between arsenic and squamous cell carcinomas of the skin, we hypothesized that arsenic exposure may be more closely associated with squamous cell carcinoma of the lung. METHODS: A comprehensive histopathological database and a detailed job-exposure matrix developed for former German uranium miners with exposure to arsenic, radon, and quartz were analyzed to quantitatively assess the effect of arsenic regarding cell type of lung cancer. The distributions of major lung cancer cell types in 1,786 German uranium miners were associated with levels of arsenic exposure under control for the other lung carcinogens. To evaluate the arsenic effects in association with a frequent occupational lung disease in miners stratification by silicosis was performed. RESULTS: There was an arsenic-related increase of the proportion of squamous cell carcinoma of the lung but restricted to miners without silicosis. The increase was found at all levels of co-exposure to radon and quartz dust. In miners with silicosis, the proportion of adenocarcinoma increased with rising arsenic exposure. Arsenic exposure was associated with non-small cell lung cancer. Silicosis turned out as major determinant of the cell type related with arsenic. CONCLUSION: These results indicate a cell type characteristic effect of arsenic in the development of lung cancer.

A study on lung cancer mortality related to radon, quartz, and arsenic exposures in German uranium miners.

Between 1946 and 1990 uranium mining was undertaken on a large scale in East Germany. This study evaluates the proportional lung cancer risk of German uranium miners from radon, quartz, and arsenic exposure during mining operations at the WISMUT Corporation. The database of the WISMUT tissue repository and a comprehensive job-exposure matrix were used to compare exposure levels of lung cancer cases with deaths from diseases of the circulatory system for risk analysis. In addition, the ratio of lung cancer cases was compared to cases from diseases of the circulatory system to the corresponding ratio in the general population. The proportional lung cancer mortality of German uranium miners was 2.9-fold higher than in the general population of East Germany. Cumulative radon, quartz, and arsenic exposure were determined as risk factors for lung cancer among German uranium miners, where silicosis modified the risk of cumulative radon and quartz exposure. Silicotics were exposed to higher levels of quartz, radon, and arsenic than nonsilicotics. Because selection of the study population was based on a tissue repository, the results need to be interpreted with caution.

Mortality among Thorotrast-exposed patients and an unexposed comparison group in the German Thorotrast study.

Thorotrast was the brand name of a stabilised colloidal solution of thorium dioxide which was used preferentially as an X-ray contrast medium for arteriography between 1930 and 1950. The administration of the medium led to lifelong chronic alpha-particle irradiation by thorium decay products, mainly in the organs of deposition. Several epidemiological follow-up studies were set up after recognition of these side-effects among which the German study was the largest. After an extended follow-up, by 2004 only nine out of 2326 originally exposed subjects were still alive (while 151 of the comparison group, which originally numbered 1890 subjects, survived) and partially more than 70 years observation and chronic exposure time could be studied allowing for further observations to be made about long-term mortality effects of Thorotrast exposure. Median life-expectancy was shortened by 14 years and mortality increased, affecting total mortality SMR=287 for males, SMR=387 for females) as well as cause-specific, especially liver cancer (SMR=16,695 and SMR=12,680, respectively), and the haematopoietic system (SMR=556 and SMR=504, respectively), but not lung cancer. Mortality (total and selected cause-specific) increased with cumulative time since first exposure.

Investigating the formation and growth of alpha-particle radiation-induced foci of altered hepatocytes: a model-based approach.

The effect of alpha-particle radiation on the formation and increase in volume of preneoplastic liver lesions was investigated in an animal experiment. Mice were divided into four groups; two groups received different doses of the alpha-particle-labeled antibody (213)Bi-anti CD19 ((213)Bi-CD19), Thorotrast was administered to one group, and one group was left untreated. Hematoxylin and eosin-stained liver sections were evaluated for preneoplastic foci of altered hepatocytes 6, 12 and 17 months after treatment. The density and size distribution of focal transections were described by a mechanistic model for the formation and growth of foci of altered hepatocytes. The negative control and the (213)Bi-CD19 groups were combined to investigate the dose-response relationship for model parameters describing the formation and growth of foci of altered hepatocytes. Although (213)Bi-CD19 was given by single injection, the effect on formation of foci of altered hepatocytes lasted for the entire experiment. Likelihood-ratio tests comparing nested models showed that (213)Bi-CD19 increases the rates of both the formation and growth of foci of altered hepatocytes. Comparing the effects of Thorotrast with those of (213)Bi-CD19 revealed that Thorotrast had an effect similar to that of a low dose of (213)Bi-CD19, but the effect on focus formation was slightly smaller whereas the effect on focus growth was slightly higher for Thorotrast, in contrast to a low dose of (213)Bi-CD19.

Role of exposure to radon and silicosis on the cell type of lung carcinoma in German uranium miners.

BACKGROUND: In East Germany, uranium mining was undertaken on a large scale from 1946 to 1990. Poor working conditions led to a high level of exposure to ionizing radiation and quartz dust. This analysis evaluates the histopathology of lung carcinoma in uranium miners in relation to radon exposure and silicosis. METHODS: A database developed for autopsy cases ascertained in a pathological tissue repository of German uranium miners was used to estimate odds ratios for developing lung carcinoma by major cell type with regard to radon exposure and silicosis. Silicosis information was extracted from autopsy protocols. Working level months (WLM) were calculated with a job-exposure matrix to assess lifetime radon exposure. Risk estimates were based on 3414 male miners who died from small cell lung carcinoma (SCLC, n = 1446), squamous cell carcinoma (SqCC, n = 1006), or adenocarcinoma (AC, n = 962) between 1957 and 1990. RESULTS: SCLC and SqCC seem more likely to be associated with high radon exposure than AC. Mean cumulative radon exposure was 868 (SD 631) WLM in SCLC, 871 (SD 652) WLM in SqCC, and 743 (SD 598) WLM in AC. Silicosis prevalence was 26% in SCLC, 38% in SqCC, and 30% in AC. In silicotics, AC and SqCC had a relatively higher frequency at the expense of SCLC. SCLC occurred earlier than AC and SqCC. CONCLUSION: High radon exposure was associated with a higher relative frequency of SCLC and SqCC than AC. Silicosis tended to increase the appearance of SqCC and AC.

Apoptosis and age-dependant induction of nuclear and mitochondrial etheno-DNA adducts in Long-Evans Cinnamon (LEC) rats: enhanced DNA damage by dietary curcumin upon copper accumulation.

Long-Evans Cinnamon (LEC) rats, a model for human Wilson's disease, develop chronic hepatitis and liver tumors owing to accumulation of copper and induced oxidative stress. Lipid peroxidation (LPO)-induced etheno-DNA adducts in nuclear- and mitochondrial-DNA along with apoptosis was measured in LEC rat liver. Levels of etheno-DNA adducts (1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxycytidine) increased with age reaching a peak at 8 and 12 weeks in nuclear and mitochondrial DNA, respectively. This is the first demonstration that etheno-DNA adducts are also formed in mitochondrial DNA. Apoptosis was assessed by TUNEL+ cells in liver sections. CD95L RNA expression was also measured by in situ hybridization in the same sections. The highest nuclear DNA adduct levels coincided with a reduced apoptotic rate at 8 weeks. Mitochondrial-DNA adducts peaked at 12 weeks that coincided with the highest apoptotic rate, suggesting a link of etheno-DNA adducts in mitochondrial DNA to apoptosis. The DNA damage in liver was further enhanced and sustained by 0.5% curcumin in the diet. Treatment for 2 weeks elevated etheno-DNA adducts 9- to 25-fold in nuclear DNA and 3- to 4-fold in mitochondrial-DNA, providing a plausible explanation as to why in our earlier study [Frank et al. (2003) Mutat. Res., 523-524, 127-135], curcumin failed to prevent liver tumors in LEC rats. Our results also confirm the reported in vitro DNA damaging potential of curcumin in the presence of copper ions by reactive oxygen species. LPO-induced adduct formation in nuclear and mitochondrial DNA appear as early lesions in LEC rat liver carcinogenesis and are discussed in relation to apoptotic events in the progression of malignant disease.

No prevention of liver and kidney tumors in Long-Evans Cinnamon rats by dietary curcumin, but inhibition at other sites and of metastases.

Long-Evans Cinnamon (LEC) rats, an inbred mutant strain which accumulates copper due to an aberrant copper-transporting ATPase gene, develop acute hepatitis, chronic liver injury and liver tumors as a result of copper-induced oxidative stress, lipid peroxidation and DNA damage. Curcumin, an antioxidant and anti-inflammatory agent, has shown anticancer properties in many rodent models. We investigated the modulating role of curcumin in liver and kidney carcinogenesis in LEC rats. Two groups of 4-week-old LEC rats (n = 60 each) were fed either a standard diet (control) or received 0.5% curcumin in the diet for life. In untreated LEC rats, the rate of acute liver failure, the incidence of liver tumors and of kidney tumors were 32, 100 and 10% respectively, which was not altered by curcumin treatment. However, curcumin reduced tumor incidence at other organ sites (15% versus 0%; P = 0.025) and suppressed formation of metastases (18% versus 0%; P = 0.01). Median survival time was decreased from 88.7 to 78.1 weeks in curcumin-treated rats (P = 0.002). The lack of chemoprevention of liver and kidney tumors in LEC rats by curcumin may be caused by enhanced toxicity and oxidative stress due to excess copper. We conclude that curcumin should be contra-indicated for patients suffering from inherited and acquired metal storage diseases that include patients with hepatitis C virus infection.