Lung cancer risk and occupational exposure to meat and live animals

Lung cancer risk associated with occupations in women: a pooling study

BACKGROUND

Occupation is an important risk factor for lung cancer. This knowledge is mainly based on studies conducted on men, with the results being generalized to women.

AIMS

We aimed to identify the relationship between different occupations and lung cancer in women.

METHODS

Pooling study in which data were pooled from six case-control studies conducted at 13 Spanish hospitals and 1 hospital in Portugal. Each woman's longest held job was coded as per the ISCO-08. Results were adjusted for age, smoking, and exposure to residential radon.

RESULTS

The study population comprised 1262 women: 618 cases and 644 controls. The reference group were white-collar workers. The adjusted multivariate analysis showed a higher risk of developing lung cancer among teaching professionals (odds ratio [OR]: 4.36; 95% confidence interval [CI] 1.73-11.02), cooks (OR: 3.59; 95% CI 1.52-8.48), domestic cleaners and helpers (OR: 2.98; 95% CI 1.54-5.78), homemakers (OR: 2.30; 95% CI 1.26-4.21) and crop farmers, livestock farmers and gardeners (OR: 2.06, 95% CI: 1.11-3.81). For adenocarcinoma, the highest risk was observed in teaching professionals, and for small-cell carcinoma, the highest risk was observed in cooks. Higher risks were observed for small-cell carcinoma compared to other histological types.

CONCLUSIONS

Some occupations may be associated with an increased risk of lung cancer in women and this risk could vary by histologic subtype; however, further research is needed to confirm these associations. In any case, protection measures must be implemented in the workplace aimed at reducing the risk of lung cancer among women workers, and more studies exclusively focused on women are warranted.

Infectious Agents in Bovine Red Meat and Milk and Their Potential Role in Cancer and Other Chronic Diseases

Red meat and dairy products have frequently been suggested to represent risk factors for certain cancers, chronic neurodegenerative diseases, and autoimmune and cardiovascular disorders. This review summarizes the evidence and investigates the possible involvement of infectious factors in these diseases. The isolation of small circular single-stranded DNA molecules from serum and dairy products of Eurasian Aurochs (Bos taurus)-derived cattle, obviously persisting as episomes in infected cells, provides the basis for further investigations. Gene expression of these agents in human cells has been demonstrated, and frequent infection of humans is implicated by the detection of antibodies in a high percentage of healthy individuals. Epidemiological observations suggest their relationship to the development multiple sclerosis, to heterophile antibodies, and to N-glycolylneuraminic acid (Neu5Gc) containing cell surface receptors.

Excess lung cancer occurrence in poultry plants. Occupational risk factors: Findings for oncogenic viruses exposure and other occupational exposures

Certain viruses naturally infect and cause cancer in chickens and turkeys. Humans are widely exposed. The viruses cause cancer in primates, and transform human cells in vitro, but it is not known if they cause cancer in humans, mainly because of the lack of epidemiologic evidence. We conducted cohort mortality studies of workers in poultry slaughtering/processing plants across the United States, because they have the highest human exposures. An excess of lung cancer and other deaths was recorded in the poultry workers. Here, we report on a case-cohort study of the lung cancer deaths nested within these cohorts, that was conducted to provide epidemiologic evidence linking these viruses with human cancer occurrence, while adjusting for possible confounders, including workplace chemical carcinogens. We obtained interviews for 339 lung cancer deaths and 457 controls, selected from our combined cohorts of 30,411 poultry plant workers and 16,405 non-poultry workers, belonging to United Food & Commercial Workers unions. Data was analyzed by both logistic regression and Cox regression, adjusting for smoking and other confounders. Lung cancer risk was independently associated with tasks or work areas indicative of exposure to both poultry oncogenic viruses and to workplace chemical carcinogens. The study provides an incremental piece of evidence (epidemiologic), indirectly linking the oncogenic viruses of poultry with the occurrence of cancer in humans, and thus may have public health implications, but the limitations highlighted must be considered. Confirmatory studies, particularly molecular studies providing definitive proof of poultry oncogenic retrovirus integration in human DNA are needed, before the findings observed in this study can be put into proper perspective.

Association between butchers and cancer mortality and incidence: A systematic review and meta-analysis

BACKGROUND

In this study, we evaluated whether increased risks of mortality and cancer incidence exist among butchers worldwide. To achieve this goal, we conducted a systematic review and meta-analysis to investigate the correlations of the risks of cancer death and incidence with male and female butchers.

METHODS

We obtained data by performing a comprehensive literature search in several databases for eligible studies published before March 2017. Multivariable-adjusted standardized mortality ratios (SMRs) and odds ratio (OR), as well as associated 95% confidence intervals (CIs) and those by subgroups, were extracted and pooled.

RESULTS

A total of 17 observational studies comprising 397,726 participants were included in the meta-analysis. The butcher occupation was not associated with all-cancer mortality risk, with pooled overall SMRs of 1.07 (95% CI 0.96-1.20). However, the pooled ORs revealed that butchers hold an elevated risk of total cancer incidence (OR, 1.51; 95% CI, 1.33-1.73). No proof of publication bias was obtained, and the findings were consistent in the subgroup analyses.

CONCLUSION

Our results suggest that working as butchers did not significantly influence all-cancer mortality risk but significantly contributed to elevated all-cancer incidence risk. Nevertheless, well-designed observational studies on this topic are necessary to confirm and update our findings.

Jaagsiekte sheep retrovirus detected in human lung cancer tissue arrays

Background

Adenocarcinoma is the most common type of non-small cell lung cancer and is frequently observed in non-smoking patients. Adenocarcinoma in-situ (formerly referred to as bronchioloalveolar carcinoma) is a subset of lung adenocarcinoma characterized by growth along alveolar septae without evidence of stromal, vascular, or pleural invasion, that disproportionately affects never-smokers, women, and Asians. Adenocarcinoma in-situ is morphologically and histologically similar to a contagious lung neoplasm of sheep called ovine pulmonary adenocarcinoma (OPA). OPA is caused by infection with the exogenous betaretrovirus, jaagsiekte sheep retrovirus (JSRV), whose envelope protein (Env) is a potent oncogene. Several studies have reported that a proportion of human lung adenocarcinomas are immunopositive for an antigen related to the Gag protein of JSRV, however other groups have been unable to verify these observations by PCR.

Methods

Here we examine human lung cancer tissue arrays (TA) for evidence of JSRV Env protein and DNA by immunohistochemical staining and PCR, respectively.

Results

Our results reveal that a subset of human lung cancers express an antigen that reacts with a JSRV Env-specific monoclonal antibody in immunohistochemistry and that exogenous JSRV-like env and gag sequences can be amplified from TA tumor samples, albeit inefficiently.

Conclusions

While a causative role has not been established, these data suggest that a JSRV-like virus might infect humans. With next generation sequencing approaches, a JSRV-like virus in human lung cancers may be identified which could have profound implications for prevention, diagnosis and therapy.

Metagenomic detection of viruses in aerosol samples from workers in animal slaughterhouses

Published studies have shown that workers in animal slaughterhouses are at a higher risk of lung cancers as compared to the general population. No specific causal agents have been identified, and exposures to several chemicals have been examined and found to be unrelated. Evidence suggests a biological aetiology as the risk is highest for workers who are exposed to live animals or to biological material containing animal faeces, urine or blood. To investigate possible biological exposures in animal slaughterhouses, we used a metagenomic approach to characterise the profile of organisms present within an aerosol sample. An assessment of aerosol exposures for individual workers was achieved by the collection of personal samples that represent the inhalable fraction of dust/bioaerosol in workplace air in both cattle and sheep slaughterhouses. Two sets of nine personal aerosol samples were pooled for the cattle processing and sheep processing areas respectively, with a total of 332,677,346 sequence reads and 250,144,492 sequence reads of 85 bp in length produced for each. Eukaryotic genome sequence was found in both sampling locations, and bovine, ovine and human sequences were common. Sequences from WU polyomavirus and human papillomavirus 120 were detected in the metagenomic dataset from the cattle processing area, and these sequences were confirmed as being present in the original personal aerosol samples. This study presents the first metagenomic description of personal aerosol exposure and this methodology could be applied to a variety of environments. Also, the detection of two candidate viruses warrants further investigation in the setting of occupational exposures in animal slaughterhouses.

Risk of lung cancer and occupational history: results of a French population-based case-control study, the ICARE study

OBJECTIVES

To assess the risk of lung cancer associated with occupations and industries.

METHODS

A French population-based case-control study included 2923 cases and 3555 controls. Lifelong occupational history was collected. Two lists of occupations known (A) or suspected (B) to be associated with lung cancer were used. Occupations and industries not included in these lists were also explored.

RESULTS

Among men, the smoking-adjusted odds ratio was 1.97 for list A (attributable fraction: 12.3%), 1.4 for list B (due especially to carpenters/joiners and transport workers). Among unlisted occupations, excess risks were found for welders, plumbers, and several construction crafts. Odds ratios among women were elevated for list A, list B (due especially to launderers/dry cleaners), cleaners and hairdressers.

CONCLUSIONS

These results confirm the role of known occupations and give insight into new occupational risk factors among men and women.

Red meat consumption and cancer: reasons to suspect involvement of bovine infectious factors in colorectal cancer

An increased risk for colorectal cancer has been consistently reported for long-time consumption of cooked and processed red meat. This has frequently been attributed to chemical carcinogens arising during the cooking process of meat. Long-time fish or poultry consumption apparently does not increase the risk, although similar or higher concentrations of chemical carcinogens were recorded in their preparation for consumption. The geographic epidemiology of colorectal cancer seems to correspond to regions with a high rate of beef consumption. Countries with a virtual absence of beef in the diet (India) or where preferably lamb or goat meat is consumed (several Arabic countries) reveal low rates of colorectal cancer. In China, pork consumption has a long tradition, with an intermediate colorectal cancer rate. In Japan and Korea, large scale beef and pork imports started after World War II or after the Korean War. A steep rise in colorectal cancer incidence was noted after 1970 in Japan and 1990 in Korea. The consumption of undercooked beef (e.g., shabu-shabu, Korean yukhoe and Japanese yukke) became very popular in both countries. The available data are compatible with the interpretation that a specific beef factor, suspected to be one or more thermoresistant potentially oncogenic bovine viruses (e.g., polyoma-, papilloma- or possibly single-stranded DNA viruses) may contaminate beef preparations and lead to latent infections in the colorectal tract. Preceding, concomitant or subsequent exposure to chemical carcinogens arising during cooking procedures should result in increased risk for colorectal cancer synergistic with these infections.

Occupational exposure to dusts and risk of renal cell carcinoma

BACKGROUND

Occupational exposures to dusts have generally been examined in relation to cancers of the respiratory system and have rarely been examined in relation to other cancers, such as renal cell carcinoma (RCC). Although previous epidemiological studies, though few, have shown certain dusts, such as asbestos, to increase renal cancer risk, the potential for other occupational dust exposures to cause kidney damage and/or cancer may exist. We investigated whether asbestos, as well as 20 other occupational dust exposures, were associated with RCC risk in a large European, multi-center, hospital-based renal case-control study.

METHODS

General occupational histories and job-specific questionnaires were reviewed by occupational hygienists for subject-specific information. Odds ratios (ORs) and 95% confidence intervals (95% CIs) between RCC risk and exposures were calculated using unconditional logistic regression.

RESULTS

Among participants ever exposed to dusts, significant associations were observed for glass fibres (OR: 2.1; 95% CI: 1.1-3.9), mineral wool fibres (OR: 2.5; 95% CI: 1.2-5.1), and brick dust (OR: 1.5; 95% CI: 1.0-2.4). Significant trends were also observed with exposure duration and cumulative exposure. No association between RCC risk and asbestos exposure was observed.

CONCLUSION

Results suggest that increased RCC risk may be associated with occupational exposure to specific types of dusts. Additional studies are needed to replicate and extend findings.

Lung cancer and occupation: A New Zealand cancer registry-based case-control study

BACKGROUND

There are many proven and suspected occupational causes of lung cancer, which will become relatively more important over time, as smoking prevalence decreases.

METHODS

We interviewed 457 cases aged 20-75 years notified to the New Zealand Cancer Registry during 2007-2008, and 792 population controls. We collected information on demographic details, potential confounders, and employment history. Associations were estimated using logistic regression adjusted for gender, age, ethnicity, smoking, and socio-economic status.

RESULTS

Among occupations of a priori interest, elevated odds ratios (ORs) were observed for sawmill, wood panel and related wood-processing plant operators (OR 4.63; 95% CI 1.05-20.29), butchers (OR 8.77, 95% CI 1.06-72.55), rubber and plastics products machine operators (4.27; 1.16-15.66), heavy truck drivers (2.24; 1.19-4.21) and workers in petroleum, coal, chemical and associated product manufacturing (1.80; 1.11-2.90); non-significantly elevated risks were also observed for loggers (4.67; 0.81-27.03), welders and flame-cutters (2.50; 0.86-7.25), pressers (5.74; 0.96-34.42), and electric and electronic equipment assemblers (3.61; 0.96-13.57). Several occupations and industries not of a priori interest also showed increased risks, including nursing associate professionals (5.45; 2.29-12.99), enrolled nurses (7.95; 3.10-20.42), care givers (3.47; 1.40-8.59), plant and machine operators and assemblers (1.61; 1.20-2.16), stationary machine operators and assemblers (1.67; 1.22-2.28), food and related products processing machine operators (1.98; 1.23-3.19), laborers and related elementary service workers (1.45; 1.05-2.00), manufacturing (1.34; 1.02-1.77), car retailing (3.08; 1.36-6.94), and road freight transport (3.02; 1.45-6.27).

CONCLUSIONS

Certain occupations and industries have increased lung cancer risks in New Zealand, including wood workers, metal workers, meat workers, textile workers and drivers. Am. J. Ind. Med. 54:89-101, 2011. © 2010 Wiley-Liss, Inc.

Occupational sunlight exposure and risk of renal cell carcinoma

BACKGROUND

Recent findings indicate that vitamin D obtained from ultraviolet (UV) exposure may reduce the risk of several different cancers. Vitamin D is metabolized to its active form within the kidney, which is the major organ for vitamin D metabolism and activity. Because both the incidence of renal cell carcinoma (RCC) and the prevalence of vitamin D deficiency have increased over the past few decades, in the current study, the authors explored whether occupational UV exposure was associated with RCC risk.

METHODS

A hospital-based, case-control study of 1097 patients with RCC (cases) and 1476 controls was conducted in 4 Central and Eastern European countries. Demographic and occupational information was collected to examine the association between occupational UV exposure and RCC risk.

RESULTS

A significant reduction (24%-38%) in the risk of RCC was observed with increasing occupational UV exposure among men who participated in the study. No association between UV exposure and RCC risk was observed among women who participated. When the analyses were stratified by latitude as another estimate of sunlight intensity, a stronger reduction (71%-73%) in the risk of RCC was observed between UV exposure and cancer risk among men who resided at the highest latitudes.

CONCLUSIONS

The current results suggested that, among men, there is an inverse association between occupational UV exposure and the risk of RCC. Replication studies are warranted to confirm these results.

Renal cell carcinoma, occupational pesticide exposure and modification by glutathione S-transferase polymorphisms

This study investigated associations between occupational pesticide exposure and renal cell carcinoma (RCC) risk. To follow-up on a previous report by Buzio et al., we also considered whether this association could be modified by glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) genotypes. About 1097 RCC cases and 1476 controls from Central and Eastern Europe were interviewed to collect data on lifetime occupational histories. Occupational information for jobs held for at least 12 months duration was coded for pesticide exposures and assessed for frequency and intensity of exposure. GSTM1 and GSTT1 gene deletions were analyzed using TaqMan assays. A significant increase in RCC risk was observed among subjects ever exposed to pesticides [odds ratio (OR): 1.60; 95% confidence interval (CI): 1.00-2.55]. After stratification by genotypes, increased risk was observed among exposed subjects with at least one GSTM1 active allele (OR: 4.00; 95% CI: 1.55-10.33) but not among exposed subjects with two GSTM1 inactive alleles compared with unexposed subjects with two inactive alleles (P-interaction: 0.04). Risk was highest among exposed subjects with both GSTM1 and GSTT1 active genotypes (OR: 6.47; 95% CI: 1.82-23.00; P-interaction: 0.02) compared with unexposed subjects with at least one GSTM1 or T1 inactive genotype. In the largest RCC case-control study with genotype information conducted to date, we observed that risk associated with pesticide exposure was exclusive to individuals with active GSTM1/T1 genotypes. These findings further support the hypothesis that glutathione S-transferase polymorphisms can modify RCC risk associated with occupational pesticide exposure.

Occupational exposures, environmental tobacco smoke, and lung cancer

BACKGROUND

There is uncertainty regarding the association of occupational exposures with lung cancer. We have studied the association between 52 high-risk job titles and lung cancer incidence in a large prospective study, with more than 200,000 participants followed for more than 6 years and 809 incident cases of lung cancer.

METHODS

Hazard ratios and 95% confidence intervals were computed by the Cox proportional-hazard regression model, adjusting for country, age, sex, social class, diet, physical activity, and smoking habits. We used a CAREX-based job-exposure matrix to infer exposure to lung carcinogens. False-positive report probability was calculated as a measure of potentially false-positive results.

RESULTS

Eighteen occupations, mainly related with agriculture, constructions, and metal processing, were associated with increased risk. In addition, incidence tended to increase with the number of hazardous jobs reported. When the occupations were classified according to the presumed exposure to specific carcinogenic agents, the hazard ratios were 1.5 (95% confidence interval = 1.2-1.9) for asbestos, 1.4 (1.1-1.8) for heavy metals, 1.4 (1.1-1.8) for polycyclic aromatic hydrocarbons, and 1.6 (1.2-2.1) for work-related environmental tobacco smoke. The estimated population attributable risk for employment in at least 1 at-risk job was 16% in men and 12% in women.

CONCLUSIONS

This large prospective study suggests that exposure to occupational lung carcinogens is still a problem, with such exposures producing moderate to large increases in risk.