Cancer in asbestos-exposed occupational cohorts: a meta-analysis

Association between Asbestos Exposure and the Incidence of Kidney Cancer: a Weight-of-Evidence Evaluation and Meta-analysis

PURPOSE OF REVIEW

Occupational asbestos exposure has been extensively linked to various cancers, with ongoing debates regarding its association with kidney cancer. This study aims to investigate the correlation between occupational asbestos exposure and kidney cancer incidence. Additionally, potential influencing factors are analyzed to enhance the comprehension of the relationship between asbestos exposure and kidney cancer.

RECENT FINDING

While asbestos has established strong associations with malignant mesothelioma and lung cancer, its connection to other malignancies such as gastric, colorectal, and kidney cancers remains under scrutiny. The current study presents mixed opinions on the relationship between asbestos exposure and kidney cancer. Our analysis revealed a potential association between asbestos exposure and the incidence of kidney cancer. Notably, among different types of asbestos, exposure to amphibole appeared to be particularly linked to a higher incident risk of kidney cancer.

Oral Cavity Squamous Cell Carcinoma Risk Factors: State of the Art

Head and neck (HN) squamous cell carcinomas (SCCs) originate from the epithelial cells of the mucosal linings of the upper aerodigestive tract, which includes the oral cavity, the pharynx, the larynx, and the sinonasal cavities. There are many associated risk factors, including alcohol drinking coupled with tobacco use, which accounts for 70% to 80% of HNSCCs. Human papilloma virus (HPV) is another independent risk factor for oropharyngeal SCC, but it is only a minor contributor to oral cavity SCC (OSCC). Betel quid chewing is also an established risk factor in southeast Asian countries. However, OSCC, and especially oral tongue cancer, incidence has been reported to be increasing in several countries, suggesting risk factors that have not been identified yet. This review summarizes the established risk factors for oral cavity squamous cell carcinomas and examines other undemonstrated risk factors for HNSCC.

Attributable Fraction of Cancer Related to Occupational Exposure in Italy

BACKGROUND

Exposure to occupational carcinogens is an important and avoidable cause of cancer. We aimed to provide an evidence-based estimate of the burden of occupation-related cancers in Italy.

METHODS

The attributable fraction (AF) was calculated based on the counterfactual scenario of no occupational exposure to carcinogens. We included exposures classified as IARC group 1 and with reliable evidence of exposure in Italy. Relative risk estimates for selected cancers and prevalences of exposure were derived from large-scale studies. Except for mesothelioma, a 15-20-year latency period between exposure and cancer was considered. The data on cancer incidence in 2020 and mortality in 2017 in Italy were obtained from the Italian Association of Cancer Registries.

RESULTS

The most prevalent exposures were UV radiation (5.8%), diesel exhaust (4.3%), wood dust (2.3%) and silica dust (2.1%). Mesothelioma had the largest AF to occupational carcinogens (86.6%), followed by sinonasal cancer (11.8%) and lung cancer (3.8%). We estimated that 0.9% of cancer cases (N~3500) and 1.6% of cancer deaths (N~2800) were attributable to occupational carcinogens in Italy. Of these, about 60% were attributable to asbestos, 17.5% to diesel exhaust, followed by chromium and silica dust (7% and 5%).

CONCLUSIONS

Our estimates provide up-to-date quantification of the low, but persistent, burden of occupational cancers in Italy.

From properties to toxicity: Comparing microplastics to other airborne microparticles

Microplastic (MP) debris is considered as a potentially hazardous material. It is omnipresent in our environment, and evidence that MP is also abundant in the atmosphere is increasing. Consequently, the inhalation of these particles is a significant exposure route to humans. Concerns about potential effects of airborne MP on human health are rising. However, currently, there are not enough studies on the putative toxicity of airborne MP to adequately assess its impact on human health. Therefore, we examined potential drivers of airborne MP toxicity. Physicochemical properties like size, shape, ζ-potential, adsorbed molecules and pathogens, and the MP's bio-persistence have been proposed as possible drivers of MP toxicity. Since their role in MP toxicity is largely unknown, we reviewed the literature on toxicologically well-studied non-plastic airborne microparticles (asbestos, silica, soot, wood, cotton, hay). We aimed to link the observed health effects and toxicology of these microparticles to the abovementioned properties. By comparing this information with studies on the effects of airborne MP, we analyzed possible mechanisms of airborne MP toxicity. Thus, we provide a basis for a mechanistic understanding of airborne MP toxicity. This may enable the assessment of risks associated with airborne MP pollution, facilitating effective policymaking and product design.

Increased Risk of Gastric Cancer in Asbestos-Exposed Workers: A Retrospective Cohort Study Based on Taiwan Cancer Registry 1980-2015

Asbestos has been recognized as a human carcinogen associated with malignant mesothelioma, cancers of lung, larynx, and ovary. However, a putative association between gastric cancer and asbestos exposure remains controversial. In this study, we aimed to explore gastric cancer risk of workers potentially exposed to asbestos in Taiwan. The asbestos occupational cohort was established from 1950 to 2015 based on the Taiwan Labor Insurance Database, and Taiwan Environmental Protection Agency regulatory datasets, followed by the Taiwan Cancer Registry for the period 1980–2015. Standardized incidence ratios (SIRs) for cancer were computed for the whole cohort using reference rates of the general population, and also reference labor population. Compared with the general population, SIR of the asbestos occupational cohort for the gastric cancer increased both in males (1.05, 95% confidence interval (CI): 1.02–1.09) and females (1.10, 95% CI: 1.01–1.18). A total of 123 worksites were identified to have cases of malignant mesothelioma, where increased risk for gastric cancer was found with a relative risk of 1.76 (95% CI: 1.63–1.90). This 35-year retrospective cohort study of asbestos-exposed workers in Taiwan may provide support for an association between occupational exposure to asbestos and gastric cancer.

Association between longest-held occupation and Social Security Disability Insurance benefits receipt

INTRODUCTION

The cost of the Social Security Disability Insurance (DI) program has increased over time though recent reports showed that disability incidence and prevalence rates have started declining. We explored whether occupation was one of the risk factors for the rising number of disabled workers who received DI benefits during 1992-2016.

METHODS

We used a cohort of 16 196 Health and Retirement Survey respondents between the age of 51 and 64 years who were followed from their date of entry until they received DI benefits, died, reached full retirement age, or reached the end of the follow-up period (2016). We used the extended stratified Cox proportional hazard model. Because one-third of the respondents in our cohort did not report their longest-held occupation, we used a multiple-imputation method.

RESULTS

The hazard of receiving DI benefits was 51%, 78%, 81%, and 85% higher among workers with longest-held occupations in sales, mechanics and repair, protective services, and personal services, respectively than among workers with longest-held occupations in the reference managerial occupation. The hazard of receiving DI benefits was more than double among workers with longest-held occupations in the construction trade and extractors, transportation operation, machine operators, handlers, and food preparation than among workers with the longest-held occupation in the reference managerial occupation.

CONCLUSION

Improving the overall working conditions in these occupations would help reduce worker suffering and the number of applicants for DI benefits, thereby reducing the burden of workplace injury and illness on the DI program.

Silica and asbestos exposure at work and the risk of bladder cancer in Canadian men: a population-based case-control study

Background

Silica and asbestos are recognized lung carcinogens. However, their role in carcinogenesis at other organs is less clear. Clearance of inhaled silica particles and asbestos fibers from the lungs may lead to translocation to sites such as the bladder where they may initiate carcinogenesis. We used data from a Canadian population-based case-control study to evaluate the associations between these workplace exposures and bladder cancer.

Methods

Data from a population-based case-control study were used to characterize associations between workplace exposure to silica and asbestos and bladder cancer among men. Bladder cancer cases (N = 658) and age-frequency matched controls (N = 1360) were recruited within the National Enhanced Cancer Surveillance System from eight Canadian provinces (1994–97). Exposure concentration, frequency and reliability for silica and asbestos were assigned to each job, based on lifetime occupational histories, using a combination of job-exposure profiles and expert review. Exposure was modeled as ever/never, highest attained concentration, duration (years), highest attained frequency (% worktime) and cumulative exposure. Odds ratios (OR) and their 95% confidence intervals (CI) were estimated using adjusted logistic regression.

Results

A modest (approximately 20%) increase in bladder cancer risk was found for ever having been exposed to silica, highest attained concentration and frequency of exposure but this increase was not statistically significant. Relative to unexposed, the odds of bladder cancer were 1.41 (95%CI: 1.01–1.98) times higher among men exposed to silica at work for ≥27 years. For asbestos, relative to unexposed, an increased risk of bladder cancer was observed for those first exposed ≥20 years ago (OR:2.04, 95%CI:1.25–3.34), those with a frequency of exposure of 5–30% of worktime (OR:1.45, 95%CI:1.06–1.98), and for those with < 10 years of exposure at low concentrations (OR:1.75, 95%CI:1.10–2.77) and the lower tertile of cumulative exposure (OR:1.69, 95%CI:1.07–2.65). However, no clear exposure-response relationships emerged.

Conclusions

Our results indicate a slight increase in risk of bladder cancer with exposure to silica and asbestos, suggesting that the effects of these agents are broader than currently recognized. The findings from this study inform evidence-based action to enhance cancer prevention efforts, particularly for workers in industries with regular exposure.

Global and regional burden of cancer in 2016 arising from occupational exposure to selected carcinogens: a systematic analysis for the Global Burden of Disease Study 2016

OBJECTIVES

This study provides a detailed analysis of the global and regional burden of cancer due to occupational carcinogens from the Global Burden of Disease 2016 study.

METHODS

The burden of cancer due to 14 International Agency for Research on Cancer Group 1 occupational carcinogens was estimated using the population attributable fraction, based on past population exposure prevalence and relative risks from the literature. The results were used to calculate attributable deaths and disability-adjusted life years (DALYs).

RESULTS

There were an estimated 349 000 (95% Uncertainty Interval 269 000 to 427 000) deaths and 7.2 (5.8 to 8.6) million DALYs in 2016 due to exposure to the included occupational carcinogens-3.9% (3.2% to 4.6%) of all cancer deaths and 3.4% (2.7% to 4.0%) of all cancer DALYs; 79% of deaths were of males and 88% were of people aged 55 -79 years. Lung cancer accounted for 86% of the deaths, mesothelioma for 7.9% and laryngeal cancer for 2.1%. Asbestos was responsible for the largest number of deaths due to occupational carcinogens (63%); other important risk factors were secondhand smoke (14%), silica (14%) and diesel engine exhaust (5%). The highest mortality rates were in high-income regions, largely due to asbestos-related cancers, whereas in other regions cancer deaths from secondhand smoke, silica and diesel engine exhaust were more prominent. From 1990 to 2016, there was a decrease in the rate for deaths (-10%) and DALYs (-15%) due to exposure to occupational carcinogens.

CONCLUSIONS

Work-related carcinogens are responsible for considerable disease burden worldwide. The results provide guidance for prevention and control initiatives.

Asbestos exposure and haematological malignancies: a Danish cohort study

Environmental asbestos exposure and occupational asbestos exposure increase the risk of several types of cancer, but the role of such exposures for haematological malignancies remains controversial. We aimed to examine the risk of haematological malignancies: first, in subjects exposed early in life, independently of any occupational exposure occurring later; second, in subjects exposed occupationally. We established an environmentally exposed cohort from four schools located near the only former asbestos cement production plant in Denmark. We identified nearly all pupils in the seventh grade and created an age and sex-matched 1:9 reference cohort from the Danish Central Population Register. Participants were born 1940-1970 and followed up in national registers until the end of 2015. Occupational asbestos exposure was assessed for all participants using two different job exposure matrices. The school cohort included 12,111 participants (49.7% girls) and the reference cohort 108,987 participants. Eight subgroups of haematological malignancy were identified in the Danish Cancer Registry. These cases were analysed for combined overall haematological malignancy, a combined subgroup of lymphomas and a combined subgroup of leukaemias. The data were analysed using Cox regression (hazard ratios (HR)) including other cancers and death as competing risks. Haematological malignancy was identified in 1125 participants. The median follow-up was 49.3 years (0.1-63.4). Early environmental asbestos exposure was not associated with an increased risk of haematological malignancy. Long-term occupational asbestos exposure was associated with overall haematological malignancy (HR 1.69, 95% CI 1.04-2.73); in particular for the leukaemia subgroup (HR 2.14, 95% CI 1.19-3.84). This large follow-up study suggests that long-term occupational asbestos exposure is associated with increased leukaemia risk. However, further studies are needed to confirm these observations.

Exposure to asbestos and the risk of colorectal cancer mortality: a systematic review and meta-analysis

Asbestos exposure is associated with mesothelioma and cancer of the lung, larynx and ovary. However, the association between asbestos exposure and colorectal cancer is controversial despite several systematic reviews of the literature, including a number of meta-analyses. We performed a systematic review and meta-analysis to evaluate quantitatively the association between exposure to asbestos and colorectal cancer. We searched for articles on occupational asbestos exposure and colorectal cancer in PubMed, EMBASE and Web of Science published before April 2018. In total, 44 articles were selected and 46 cohort studies were analysed. The overall pooled risk estimates and corresponding 95% CIs of the association between occupational asbestos exposure and colorectal cancer were calculated using a random-effects model. Subgroup analyses and sensitivity tests were also performed. There was a significantly increased risk of colorectal cancer mortality among workers exposed to asbestos occupationally, with an overall pooled SMR of 1.16 (95% CI: 1.05 to 1.29). The pooled SMR for colorectal cancer was elevated in studies in which the asbestos-associated risk of lung cancer was also elevated (1.43; 95% CI: 1.30 to 1.56). This implies that the risk of colorectal cancer mortality increases as the level of asbestos exposure rises. A sensitivity analysis showed robust results and there was no publication bias. Although the effect size was small and the heterogeneity among studies was large, our findings indicate that occupational exposure to asbestos is a risk factor for colorectal cancer.

Heavy metals, welding fumes, and other occupational exposures, and the risk of kidney cancer: A population-based nested case-control study in three Nordic countries

OBJECTIVES

To determine whether occupational exposure to heavy metals (chromium (VI), iron, nickel, lead) and welding fumes is associated with the risk of kidney cancer and to describe whether other occupational exposures included in the Job Exposure Matrix of the Nordic Occupational Cancer (NOCCA) study are associated with the risk.

MATERIALS AND METHODS

Nested case-control study among individuals registered in population censuses in Finland, Iceland, and Sweden in 1960-1990. A total of 59,778 kidney cancer cases, and 298,890 controls matched on sex, age, and country. Cumulative occupational exposures to metals (chromium (VI), iron, nickel, lead), welding fumes, and 24 other occupational exposure covariates, lagged 0, 10, and 20 years.

RESULTS

Overall, there was no or very little association between kidney cancer and exposures studied. The risk was elevated in individuals with high exposure to asbestos (OR 1.19, 95%CI 1.08-1.31). The risk was significantly decreased for individuals characterized with high perceived physical workload (OR 0.86, 95%CI 0.82-0.91), high exposure to ultraviolet radiation (OR 0.85, 95%CI 0.79-0.92), and high exposure to wood dust (OR 0.82, 95%CI 0.71-0.94). The risk of kidney cancer under the age of 59 was elevated in individuals with high exposure to nickel (OR 1.49, 95%CI 1.03-2.17). The risk of kidney cancer in age 59-74 years was elevated for individuals with high exposure to iron (OR 1.41, 95%CI 1.07-1.85), and high exposure to welding fumes (OR 1.43, 95%CI 1.09-1.89).

CONCLUSIONS

The only markedly elevated risks of kidney cancer were seen for the highest exposures of nickel and iron/welding fumes in specific age strata.

Population-based cohort study on health effects of asbestos exposure in Japan

Occupational asbestos exposure occurs in many workplaces and is a well‐known cause of mesothelioma and lung cancer. However, the association between nonoccupational asbestos exposure and those diseases is not clearly described. The aim of this study was to investigate cause‐specific mortality among the residents of Amagasaki, a city in Japan with many asbestos factories, and evaluate the potential excess mortality due to established and suspected asbestos‐related diseases. The study population consisted of 143 929 residents in Amagasaki City before 1975 until 2002, aged 40 years or older on January 1, 2002. Follow‐up was carried out from 2002 to 2015. Standardized mortality ratio (SMR) with its 95% confidence interval (CI) was calculated by sex, using the mortality rate of the Japanese population as reference. A total of 38 546 deaths (including 303 from mesothelioma and 2683 from lung cancer) were observed. The SMRs in the long‐term residents’ cohort were as follows: death due to all causes, 1.12 (95% CI, 1.10‐1.13) in men and 1.07 (95% CI, 1.06‐1.09) in women; lung cancer, 1.28 (95% CI, 1.23‐1.34) in men and 1.23 (95% CI, 1.14‐1.32) in women; and mesothelioma, 6.75 (95% CI, 5.83‐7.78) in men and 14.99 (95% CI, 12.34‐18.06) in women. These SMRs were significantly higher than expected. The increased SMR of mesothelioma suggests the impact of occupational asbestos exposure among men and nonoccupational asbestos exposure among women in the long‐term residents’ cohort. In addition, the high level of excess mortality from mesothelioma has persisted, despite the mixture of crocidolite and chrysotile no longer being used for three or four decades.

Review of refractory ceramic fiber (RCF) toxicity, epidemiology and occupational exposure

This literature review on refractory ceramic fibers (RCF) summarizes relevant information on manufacturing, processing, applications, occupational exposure, toxicology and epidemiology studies. Rodent toxicology studies conducted in the 1980s showed that RCF caused fibrosis, lung cancer and mesothelioma. Interpretation of these studies was difficult for various reasons (e.g. overload in chronic inhalation bioassays), but spurred the development of a comprehensive product stewardship program under EPA and later OSHA oversight. Epidemiology studies (both morbidity and mortality) were undertaken to learn more about possible health effects resulting from occupational exposure. No chronic animal bioassay studies on RCF have been conducted since the 1980s. The results of the ongoing epidemiology studies confirm that occupational exposure to RCF is associated with the development of pleural plaques and minor decrements in lung function, but no interstitial fibrosis or incremental lung cancer. Evidence supporting a finding that urinary tumors are associated with RCF exposure remains, but is weaker. One reported, but unconfirmed, mesothelioma was found in an individual with prior occupational asbestos exposure. An elevated SMR for leukemia was found, but was absent in the highly exposed group and has not been observed in studies of other mineral fibers. The industry will continue the product stewardship program including the mortality study.

Malignant Mesothelioma of the Pleuraand Other Malignancies in the Same Patient

Aims and background

The co-existence of mesothelioma, mostly asbestos-related, and other primary malignancies has repeatedly been reported. The present study evaluated the frequency of such an occurrence.

Methods

In the period October 1979-June 2002, 215 cases of malignant pleural mesothelioma were diagnosed at the Hospital of Monfalcone, Italy. All the cases of the above series, examined at necropsy (169), were included in the study. Occupational histories had been obtained from the patients or from their relatives by personal or telephone interviews. In 132 cases, asbestos bodies were isolated after chemical digestion of lung samples. The thoracic cavities were examined for pleural plaques.

Results

Additional malignancies were observed in 32 cases (18.9%). Multiple tumors were synchronous in 22 cases, metachronous in 8 cases, and synchronous and metachronous in 2. Four different tumors were found in 2 cases, 3 malignancies were detected in 6 patients, and 2 malignancies in the remaining 24. The most frequent additional malignancies were prostate adenocarcinoma (7 cases), non-Hodgkin lymphoma or chronic lymphocytic leukaemia (5 cases), bladder carcinoma (4 cases), kidney carcinoma (4 cases), large bowel carcinoma (4 cases), and liver cell carcinoma (4 cases). All the patients had histories of exposure to asbestos, mostly in shipbuilding. Lung asbestos body burdens ranged between 60 and 230,000 per gram of dried tissue. Pleural plaques were found in 26 cases.

Conclusions

In contrast with other series of the literature, in the present cases the co-existence of mesothelioma and other malignancies appeared as a relatively frequent event. The lack of a control group does not allow definite conclusions about the meaning of the occurrence. However, the co-existence of certain tumors with asbestos-related mesothelioma suggests that mesothelioma and associated malignancies might share some etiologic factors (asbestos and others).

Italian pool of asbestos workers cohorts: mortality trends of asbestos-related neoplasms after long time since first exposure

OBJECTIVE

Asbestos is a known human carcinogen, with evidence for malignant mesothelioma (MM), cancers of lung, ovary, larynx and possibly other organs. MM rates are predicted to increase with a power of time since first exposure (TSFE), but the possible long-term attenuation of the trend is debated. The asbestos ban enforced in Italy in 1992 gives an opportunity to measure long-term cancer risk in formerly exposed workers.

METHODS

Pool of 43 previously studied Italian asbestos cohorts (asbestos cement, rolling stock, shipbuilding), with mortality follow-up updated to 2010. SMRs were computed for the 1970â€"2010 period, for the major causes, with consideration of duration and TSFE, using reference rates by age, sex, region and calendar period.

RESULTS

The study included 51 801 subjects (5741 women): 55.9% alive, 42.6% died (cause known for 95%) and 1.5% lost to follow-up. Mortality was significantly increased for all deaths (SMR: men: 1.05, 95% CI 1.03 to 1.06; women: 1.17, 95% CI to 1.12 to 1.22), all malignancies combined (SMR: men: 1.17, 95% CI to 1.14 to 1.20; women: 1.33, 95% CI 1.24 to 1.43), pleural and peritoneal malignancies (SMR: men: 13.28 and 4.77, 95% CI 12.24 to 14.37 and 4.00 to 5.64; women: 28.44 and 6.75, 95% CI 23.83 to 33.69 and 4.70 to 9.39), lung (SMR: men: 1.26, 95% CI 1.21 to 1.31; women: 1.43, 95% CI 1.13 to 1.78) and ovarian cancer (SMR=1.38, 95% CI 1.00 to 1.87) and asbestosis (SMR: men: 300.7, 95% CI 270.7 to 333.2; women: 389.6, 95% CI 290.1 to 512.3). Pleural cancer rate increased during the first 40 years of TSFE and reached a plateau after.

DISCUSSION

The study confirmed the increased risk for cancer of the lung, ovary, pleura and peritoneum but not of the larynx and the digestive tract. Pleural cancer mortality reached a plateau at long TSFE, coherently with recent reports.

Modifiable risk factors for the prevention of bladder cancer: a systematic review of meta-analyses

Each year, 430,000 people are diagnosed with bladder cancer. Due to the high recurrence rate of the disease, primary prevention is paramount. Therefore, we reviewed all meta-analyses on modifiable risk factors of primary bladder cancer. PubMed, Embase and Cochrane database were systematically searched for meta-analyses on modifiable risk factors published between 1995 and 2015. When appropriate, meta-analyses (MA) were combined in meta-meta-analysis (MMA). If not, the most comprehensive MA was selected based on the number of primary studies included. Probability of causation was calculated for individual factors and a subset of lifestyle factors combined. Of 1496 articles identified, 5 were combined in MMA and 21 were most comprehensive on a single risk factor. Statistically significant associations were found for current (RR 3.14) or former (RR 1.83) cigarette smoking, pipe (RR 1.9) or cigar (RR 2.3) smoking, antioxidant supplementation (RR 1.52), obesity (RR 1.10), higher physical activity levels (RR 0.86), higher body levels of selenium (RR 0.61) and vitamin D (RR 0.75), and higher intakes of: processed meat (RR 1.22), vitamin A (RR 0.82), vitamin E (RR 0.82), folate (RR 0.84), fruit (RR 0.77), vegetables (RR 0.83), citrus fruit (RR 0.85), and cruciferous vegetables (RR 0.84). Finally, three occupations with the highest risk were tobacco workers (RR 1.72), dye workers (RR 1.58), and chimney sweeps (RR 1.53). The probability of causation for individual factors ranged from 4 to 68 %. The combined probability of causation was 81.8 %. Modification of lifestyle and occupational exposures can considerably reduce the bladder cancer burden. While smoking remains one of the key risk factors, also several diet-related and occupational factors are very relevant.

A case of laryngeal cancer induced by exposure to asbestos in a construction site supervisor

Background

Construction site supervisors are exposed to many chemicals, dusts, and metals including asbestos. Asbestos is a hazardous chemical that is carcinogenic. Laryngeal cancer is not a rare disease in Korea. The most common causes of this disease are tobacco and alcohol, and representative occupational cause is asbestos. However, up to now, no case of laryngeal cancer induced by asbestos has been reported in Korea. In this study, we report such a case in a construction site supervisor.

Case presentation

A 60-year-old man who had been experiencing hoarseness for 2 months was diagnosed with laryngeal cancer. The pathologic diagnosis was squamous cell carcinoma in situ, based on examination of a biopsy specimen obtained by resection of the lesion. The patient had been exposed to asbestos for 38 years at construction sites where he worked until diagnosed with laryngeal cancer. He had been exposed to asbestos when demolishing buildings and inspecting materials.

Conclusion

The patient in this case worked with construction materials including asbestos and supervised construction for 38 years, and was thus exposed to asbestos at construction sites. Much of the asbestos was highly concentrated especially during demolition processes. We therefore consider the laryngeal cancer of this patient to be a work-related disease.

Working with asbestos and the possible health risks

BACKGROUND

The generic term asbestos refers to a group of crystalline mineral silicates that occur naturally in various forms. Because of their properties of strength, heat and electrical resistance and their ability to withstand corrosion by acids and sea water, asbestos was used extensively both in the UK and worldwide.

AIMS

To provide a historical perspective of this ubiquitous occupational hazard, consider the key changes in UK legislation aimed at improving the management of this occupational health risk and describe the evidence from the scientific literature concerning asbestos and disease.

METHODS

Original articles, reviews (including reference textbooks) and scientific literature in PubMed and other principal medical science databases, 1960-2014, were searched. Publications by regulatory agencies and by governmental organizations were also considered and included where relevant.

RESULTS

Asbestos remains the biggest cause of cancer deaths worldwide. For malignant mesothelioma deaths alone, it is estimated that in the UK, between 2015 and 2020, the number of cases will peak at 2500 cases annually. It is not clear whether there is a safe level of asbestos fibres in air. Evidence for the efficacy of health surveillance is lacking.

CONCLUSIONS

Although the use of asbestos was banned in the UK in 1985 (amosite and crocidolite) and 1999 (chrysotile), it remains a significant occupational risk factor for work-related morbidity and mortality, causing both benign and malignant diseases, often with long latency. Further research is needed regarding exposure levels and health surveillance.

Malignant tumors of the larynx: Clinicopathologic profile and implication for late disease presentation

Background:

Malignant laryngeal tumors are uncommon. Late presentation of the disease may worsen management outcomes. We described the epidemiologic, clinicopathologic profile, and management outcomes of laryngeal tumors in a tertiary health institution in Nigeria.

Materials and Methods:

An 11-year retrospective review of medical records of patients managed for malignant laryngeal tumor at the University College Hospital, Ibadan, Nigeria, was performed.

Results:

There were 97 patients comprising 74 (76.3%) males and 23 (23.7%) females with a mean age of 60.48 ± 12.15 years. The mean duration of illness was 7.3 ± 3.8 months. History of cigarette smoking and alcohol consumption was in 2.1% and 14.4% patients, respectively. The most common clinical presentations were hoarseness, cough, and dyspnea. Transglottis (91.8%) was the most common anatomic tumor location and 92.8% patients presented in advanced disease stage. Four histologic types were identified with squamous cell carcinoma accounting for 96.9%. About 92% patients had emergency tracheostomy and 56 (57.7%) patients had total laryngectomy. The postoperative complications were pharyngocutaneous fistula (5.2%) and peristomal recurrence (3.1%). The 5-year survival rate was 52.5%.

Conclusions:

Malignant laryngeal tumors are uncommon, but more females are getting the disease. Squamous cell carcinoma is the most common histologic variant. Late stage disease presentation and initial wrong diagnosis contributed to the poor management outcome.

Asbestos exposure and laryngeal cancer mortality

OBJECTIVES/HYPOTHESIS

Occupational exposure to asbestos occurs in many workplaces and is well known to cause asbestosis, lung cancer, and mesothelioma. However, the link between asbestos exposure and other malignancies was not confirmed. The aim of the current meta-analysis was to provide a summary measure of risk for laryngeal cancer associated with occupational asbestos exposure.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

Electronic databases were searched for studies characterizing the association between asbestos and laryngeal cancer. Standardized mortality rate (SMR) with its 95% confidence interval (CI) of each study was combined using a fixed or random effect model.

RESULTS

Significantly increased SMR for laryngeal cancer was observed when subjects were exposed to asbestos (SMR = 1.69, 95% CI = 1.45-1.97, P < .001), with little evidence of heterogeneity among studies (Q = 15.39, P = .803, I(2) = 0.0%). Effect estimates were larger for cohorts controlling for male subjects, Europe and Oceania, mining and textile industries, exposure to crocidolite, long study follow-up (>25 years), and SMR for lung cancer > 2.0. Publication bias was not detect by Begg test (P = .910) and Egger test (P = .340).

CONCLUSIONS

Our study supports the association of exposure to asbestos with an increased risk of laryngeal cancer mortality among male workers.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:1169-1174, 2016.

Stomach cancer and occupational exposure to asbestos: a meta-analysis of occupational cohort studies

Background:

A recent Monographs Working Group of the International Agency for Research on Cancer concluded that there is limited evidence for a causal association between exposure to asbestos and stomach cancer.

Methods:

We performed a meta-analysis to quantitatively evaluate this association. Random effects models were used to summarise the relative risks across studies. Sources of heterogeneity were explored through subgroup analyses and meta-regression.

Results:

We identified 40 mortality cohort studies from 37 separate papers, and cancer incidence data were extracted for 15 separate cohorts from 14 papers. The overall meta-SMR for stomach cancer for total cohort was 1.15 (95% confidence interval 1.03–1.27), with heterogeneous results across studies. Statistically significant excesses were observed in North America and Australia but not in Europe, and for generic asbestos workers and insulators. Meta-SMRs were larger for cohorts reporting a SMR for lung cancer above 2 and cohort sizes below 1000.

Conclusions:

Our results support the conclusion by IARC that exposure to asbestos is associated with a moderate increased risk of stomach cancer.

Respiratory risks from household air pollution in low and middle income countries

A third of the world's population uses solid fuel derived from plant material (biomass) or coal for cooking, heating, or lighting. These fuels are smoky, often used in an open fire or simple stove with incomplete combustion, and result in a large amount of household air pollution when smoke is poorly vented. Air pollution is the biggest environmental cause of death worldwide, with household air pollution accounting for about 3·5-4 million deaths every year. Women and children living in severe poverty have the greatest exposures to household air pollution. In this Commission, we review evidence for the association between household air pollution and respiratory infections, respiratory tract cancers, and chronic lung diseases. Respiratory infections (comprising both upper and lower respiratory tract infections with viruses, bacteria, and mycobacteria) have all been associated with exposure to household air pollution. Respiratory tract cancers, including both nasopharyngeal cancer and lung cancer, are strongly associated with pollution from coal burning and further data are needed about other solid fuels. Chronic lung diseases, including chronic obstructive pulmonary disease and bronchiectasis in women, are associated with solid fuel use for cooking, and the damaging effects of exposure to household air pollution in early life on lung development are yet to be fully described. We also review appropriate ways to measure exposure to household air pollution, as well as study design issues and potential effective interventions to prevent these disease burdens. Measurement of household air pollution needs individual, rather than fixed in place, monitoring because exposure varies by age, gender, location, and household role. Women and children are particularly susceptible to the toxic effects of pollution and are exposed to the highest concentrations. Interventions should target these high-risk groups and be of sufficient quality to make the air clean. To make clean energy available to all people is the long-term goal, with an intermediate solution being to make available energy that is clean enough to have a health impact.

Occupational asbestos exposure and lung cancer--a systematic review of the literature

The objective of this study was to evaluate the scientific literature concerning asbestos and lung cancer, emphasizing low-level exposure. A literature search in PubMed and Embase resulted in 5,864 citations. Information from included studies was extracted using SIGN. Twenty-one statements were evidence graded. The results show that histology and location are not helpful in differentiating asbestos-related lung cancer. Pleural plaques, asbestos bodies, or asbestos fibers are useful as markers of asbestos exposure. The interaction between asbestos and smoking regarding lung cancer risk is between additive and multiplicative. The findings indicate that the association between asbestos exposure and lung cancer risk is basically linear, but may level off at very high exposures. The relative risk for lung cancer increases between 1% and 4% per fiber-year (f-y)/mL, corresponding to a doubling of risk at 25-100 f-y/mL. However, one high-quality case-control study showed a doubling at 4 f-y/mL.

Lung cancer correlates in Lebanese adults: a pilot case--control study

BACKGROUND

Lung cancer is one of the most prevalent types of cancers. However, there are no epidemiological studies concerning lung cancer and its risk factors in Lebanon. This study was carried out to determine the association between lung cancer and its most common risk factors in a sample of the Lebanese population.

METHODS

A hospital-based case-control study was conducted. Patients were recruited in a tertiary health care center. A questionnaire in Arabic was designed to assess the possible risk factors for lung cancer.

RESULTS

For females, cigarette smoking (ORa=9.76) and using fuel for heating (ORa=9.12) were found to be the main risk factors for lung cancer; for males, cigarette smoking (ORa=156.98), living near an electricity generator (ORa=13.26), consuming low quantities of fruits and vegetables (ORa=10.54) and a family history of cancer (ORa=8.75) were associated with lung cancer. Waterpipe smoking was significantly correlated with lung cancer in the bivariate analysis.

CONCLUSION

In this pilot study, it was found that in addition to smoking, outdoor and indoor pollution factors were potential risk factors of lung cancer. Additional studies would be necessary to confirm these findings.

Are metals accumulated in human hair affected by naturally occurring asbestos fiber contamination? A case study from a rural area of china

Little is known about the link between metals accumulated in human and asbestos fiber contamination in the environment. Therefore, hair samples of 368 subjects (128 males and 240 females) from a rural area contaminated by crocidolite asbestos fibers were collected to investigate the distributions of 17 metals accumulated in human. The results showed that the mean concentrations of As, Al, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Na, Ni, Pb, Sr, and Zn in hair of the total subjects were 0.23, 23.36, 4.33, 0.11, 0.05, 0.70, 10.53, 29.74, 0.37, 241.57, 3.52, 0.08, 153.21, 0.72, 4.26, 10.96, and 113.35 mg/kg, respectively. Moreover, approximately 86.14, 52.17, 73.91, 85.05, 80.98, 74.46, and 53.80 % of the hair samples of the total subjects contained much higher concentrations of Al, Ba, Fe, Mg, Mn, Na, and Sr compared with the highest reference values, respectively. The mean concentrations of the determined metals (except for As, Co, Cr, Hg, and Mo) significantly varied among different age groups for both male and females. The results of correlation analysis and cluster analysis revealed that strong correlations were found between Al, Fe, Zn, Mg, and Na accumulated in human from the study area. These might suggest that Al, Ba, Fe, Mg, Mn, Na, and Sr were significantly derived from contamination of crocidolite asbestos fibers. Zn, Mg, and Na might also originate from diet. However, Cd, Mo, Co, As, Cr, Hg, Ni, Mn, Pb, and Ba accumulated in human seemed to be mainly derived from soil. It can be concluded that metals accumulated in human hair have a link with asbestos fiber contamination in the environment.

Concentrations of asbestos fibers and metals in drinking water caused by natural crocidolite asbestos in the soil from a rural area

Asbestos fibers and metals in drinking water are of significant importance to the field of asbestos toxicology. However, little is known about asbestos fibers and metals in drinking water caused by naturally occurring asbestos. Therefore, concentrations of asbestos fibers and metals in well and surface waters from asbestos and control areas were measured by scanning electron microscopy (SEM), inductively coupled plasma (ICP) optical emission spectrometer, and ICP-mass spectrometry in this study. The results indicated that the mean concentration of asbestos fibers was 42.34 millions of fibers per liter by SEM, which was much higher than the permission exposure level. The main compositions of both asbestos fibers in crocidolite mineral and in drinking water were Na, Mg, Fe, and Si based on energy dispersive X-ray analysis. This revealed that the drinking water has been contaminated by asbestos fibers from crocidolite mineral in soil and rock. Except for Cr, Pb, Zn, and Mn, the mean concentrations of Ni, Na, Mg, K, Fe, Ca, and SiO2 were much higher in both surface water and well waters from the asbestos area than in well water from the control area. The results of principal component and cluster analyses indicated that the metals in surface and well waters from the asbestos area were significantly influenced by crocidolite mineral in soil and rock. In the asbestos area, the mean concentrations of asbestos fibers and Ni, Na, Mg, K, Fe, Ca, and SiO2 were higher in surface and well waters, indicating that asbestos fibers and the metals were significantly influenced by crocidolite in soil and rock.

Variations of lung cancer risk from asbestos exposure: impact on estimation of population attributable fraction

The purpose of this study is to investigate the potential impact of differing lung cancer risks in study populations on estimating population attributable fraction (PAF) from asbestos exposure. Studies were identified via a MEDLINE search up to September 2009 and from the reference lists of publications about asbestos exposure and lung cancer risk. Relative risk estimates were extracted from 160 studies and meta-relative risks were calculated according to random-effect models. Hypothetical PAFs were calculated based on the meta results and on the difference exposure scenarios. The risks for lung cancer from asbestos exposure were variable according to the region as well as other study characteristics. The risk estimates proved higher in Asian countries (RR=3.53), in studies with 500 or fewer subjects (RR=2.26), and papers published in the 1990s or earlier (RR=1.91), than did those for European or North American countries, studies with more than 500 subjects, and papers published in the 2000s, respectively. The differences in PAFs between Asian and North American studies were 15.5%, 30.3%, and 36.2% when the exposure prevalence was 10%, 30%, and 50%, respectively. This study suggested that it is important to apply appropriate lung cancer estimates to each study population when calculating PAF from asbestos exposure.

A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010

BACKGROUND

Quantification of the disease burden caused by different risks informs prevention by providing an account of health loss different to that provided by a disease-by-disease analysis. No complete revision of global disease burden caused by risk factors has been done since a comparative risk assessment in 2000, and no previous analysis has assessed changes in burden attributable to risk factors over time.

METHODS

We estimated deaths and disability-adjusted life years (DALYs; sum of years lived with disability [YLD] and years of life lost [YLL]) attributable to the independent effects of 67 risk factors and clusters of risk factors for 21 regions in 1990 and 2010. We estimated exposure distributions for each year, region, sex, and age group, and relative risks per unit of exposure by systematically reviewing and synthesising published and unpublished data. We used these estimates, together with estimates of cause-specific deaths and DALYs from the Global Burden of Disease Study 2010, to calculate the burden attributable to each risk factor exposure compared with the theoretical-minimum-risk exposure. We incorporated uncertainty in disease burden, relative risks, and exposures into our estimates of attributable burden.

FINDINGS

In 2010, the three leading risk factors for global disease burden were high blood pressure (7·0% [95% uncertainty interval 6·2-7·7] of global DALYs), tobacco smoking including second-hand smoke (6·3% [5·5-7·0]), and alcohol use (5·5% [5·0-5·9]). In 1990, the leading risks were childhood underweight (7·9% [6·8-9·4]), household air pollution from solid fuels (HAP; 7·0% [5·6-8·3]), and tobacco smoking including second-hand smoke (6·1% [5·4-6·8]). Dietary risk factors and physical inactivity collectively accounted for 10·0% (95% UI 9·2-10·8) of global DALYs in 2010, with the most prominent dietary risks being diets low in fruits and those high in sodium. Several risks that primarily affect childhood communicable diseases, including unimproved water and sanitation and childhood micronutrient deficiencies, fell in rank between 1990 and 2010, with unimproved water and sanitation accounting for 0·9% (0·4-1·6) of global DALYs in 2010. However, in most of sub-Saharan Africa childhood underweight, HAP, and non-exclusive and discontinued breastfeeding were the leading risks in 2010, while HAP was the leading risk in south Asia. The leading risk factor in Eastern Europe, most of Latin America, and southern sub-Saharan Africa in 2010 was alcohol use; in most of Asia, North Africa and Middle East, and central Europe it was high blood pressure. Despite declines, tobacco smoking including second-hand smoke remained the leading risk in high-income north America and western Europe. High body-mass index has increased globally and it is the leading risk in Australasia and southern Latin America, and also ranks high in other high-income regions, North Africa and Middle East, and Oceania.

INTERPRETATION

Worldwide, the contribution of different risk factors to disease burden has changed substantially, with a shift away from risks for communicable diseases in children towards those for non-communicable diseases in adults. These changes are related to the ageing population, decreased mortality among children younger than 5 years, changes in cause-of-death composition, and changes in risk factor exposures. New evidence has led to changes in the magnitude of key risks including unimproved water and sanitation, vitamin A and zinc deficiencies, and ambient particulate matter pollution. The extent to which the epidemiological shift has occurred and what the leading risks currently are varies greatly across regions. In much of sub-Saharan Africa, the leading risks are still those associated with poverty and those that affect children.

FUNDING

Bill & Melinda Gates Foundation.

Impacts of land use on spatial distribution of mortality rates of cancers caused by naturally occurring asbestos

This study investigated the spatial distributions of mortality rates of six cancers: mesothelioma, lung cancer, intestinal cancer, nasopharyngeal and laryngeal cancer, liver cancer, and stomach cancer in Dayao using Geographic Information Systems. Relationships between the mortality rates of the six cancers and land use patterns were investigated by Pearson Correlation Coefficients. The results indicated that the mortality rates of nasopharyngeal and laryngeal cancer, lung cancer, intestinal cancer, and mesothelioma were significantly associated with outcropped asbestos. Both the proportions of farmland and urban area were positively related to the mortality rates of nasopharyngeal and laryngeal cancer, lung cancer, intestinal cancer, and mesothelioma, and significant negative correlations were found between the proportion of forestland and nasopharyngeal and laryngeal cancer and intestinal cancer. It can be concluded that naturally occurring asbestos may significantly elevate the mortality rates of nasopharyngeal and laryngeal cancer, intestinal cancer, lung cancer, and mesothelioma. Moreover, higher proportions of farmland, urban area, and lower proportions of forested land may elevate the mortality rate of the four cancers.

Chapter 6: Lung cancer in never smokers: epidemiology and risk prediction models

In this chapter we review the epidemiology of lung cancer incidence and mortality among never smokers/nonsmokers and describe the never smoker lung cancer risk models used by the Cancer Intervention and Surveillance Network (CISNET) modelers. Our review focuses on those influences likely to have measurable population impact on never smoker risk, such as secondhand smoke, even though the individual-level impact may be small. Occupational exposures may also contribute importantly to the population attributable risk of lung cancer. We examine the following risk factors in this chapter: age, environmental tobacco smoke, cooking fumes, ionizing radiation including radon gas, inherited genetic susceptibility, selected occupational exposures, preexisting lung disease, and oncogenic viruses. We also compare the prevalence of never smokers between the three CISNET smoking scenarios and present the corresponding lung cancer mortality estimates among never smokers as predicted by a typical CISNET model.

Environmental and modifiable risk factors in renal cell carcinoma

OBJECTIVES

Prevention of disease requires a firm understanding of the relevant environmental and modifiable risk factors. We present a comprehensive review of these factors in renal cell carcinoma.

MATERIALS AND METHODS

A literature search of the PubMed database was performed to identify clinical studies examining the relationship between environmental and modifiable factors in the development of renal cell carcinoma (terms utilized: kidney cancer; renal cell carcinoma; risk factors; environment; obesity; hypertension; trichloroethylene). An emphasis was placed on more recent studies.

RESULTS

Case control and large cohort studies have examined the relationship of numerous environmental and modifiable factors and the risk of renal cell carcinoma. Of particular note are dose-dependent increases in smokers, the obese, and hypertensive patients.

CONCLUSIONS

Environmental and modifiable risk factors contribute significantly to the risk of sporadic renal cell carcinoma. Emphasis should be placed on smoking cessation and hypertension control. Emerging evidence would suggest that dietary intake and quality impact renal cell carcinoma risk.

Investigation of occupational and environmental causes of respiratory cancers (ICARE): a multicenter, population-based case-control study in France

BACKGROUND

Occupational causes of respiratory cancers need to be further investigated: the role of occupational exposures in the aetiology of head and neck cancers remains largely unknown, and there are still substantial uncertainties for a number of suspected lung carcinogens. The main objective of the study is to examine occupational risk factors for lung and head and neck cancers.

METHODS/DESIGN

ICARE is a multi-center, population-based case-control study, which included a group of 2926 lung cancer cases, a group of 2415 head and neck cancer cases, and a common control group of 3555 subjects. Incident cases were identified in collaboration with cancer registries, in 10 geographical areas. The control group was a random sample of the population of these areas, with a distribution by sex and age comparable to that of the cases, and a distribution by socioeconomic status comparable to that of the population. Subjects were interviewed face to face, using a standardized questionnaire collecting particularly information on tobacco and alcohol consumption, residential history and a detailed description of occupational history. Biological samples were also collected from study subjects. The main occupational exposures of interest are asbestos, man-made mineral fibers, formaldehyde, polycyclic aromatic hydrocarbons, chromium and nickel compounds, arsenic, wood dust, textile dust, solvents, strong acids, cutting fluids, silica, diesel fumes, welding fumes. The complete list of exposures of interest includes more than 60 substances. Occupational exposure assessment will use several complementary methods: case-by-case evaluation of exposure by experts; development and use of algorithms to assess exposure from the questionnaires; application of job-exposure matrices.

DISCUSSION

The large number of subjects should allow to uncover exposures associated with moderate increase in risks, and to evaluate risks associated with infrequent or widely dispersed exposures. It will be possible to study joint effects of exposure to different occupational risk factors, to examine the interactions between occupational exposures, tobacco smoking, alcohol drinking, and genetic risk factors, and to estimate the proportion of respiratory cancers attributable to occupational exposures in France. In addition, information on many non-occupational risk factors is available, and the study will provide an excellent framework for numerous studies in various fields.

Occupational exposures to asbestos, polycyclic aromatic hydrocarbons and solvents, and cancers of the oral cavity and pharynx: a quantitative literature review

PURPOSE

The role of occupational risk factors in oral and pharyngeal cancer is not well known and is possibly underestimated. This quantitative review summarizes epidemiological findings on exposure to asbestos, polycyclic aromatic hydrocarbons and solvents, and cancers of the oral cavity and pharynx.

METHODS

A systematic literature search was performed. We analyzed 63 publications: 8 from case-control studies and 55 from cohort studies. For agents with at least five available studies with homogenous exposure, a series of meta-analyses was conducted to provide quantitative pooled estimates of risks, using random effect models.

RESULTS

Exposure to asbestos (meta-RR 1.25; 95% CI 1.10-1.42) and to polycyclic aromatic hydrocarbons (meta-RR 1.14; 95% CI 1.02-1.28) was found to be associated with oral and pharyngeal cancer risk. On the other hand, no association was found with exposure to solvents in general (meta-RR 0.98; 95% CI 0.77-1.23) but the strong heterogeneity between studies suggested differences in exposures. The small number of studies with homogeneous exposure did not allow meta-analyses for specific solvents.

CONCLUSIONS

Future investigations should overcome common weaknesses of past studies, in terms of sample size, characterization of exposure, and classification of cancer sites.

Case-control study of pleural mesothelioma in workers with social security in Mexico

BACKGROUND

Environmental and occupational exposure to asbestos in Mexico in the past has been a cause of deaths and health damages. Its magnitude is unknown to date. Our objective was to identify the proportion of cases of malignant pleural mesothelioma (MPM) that can be attributed to and occupational exposure to asbestos.

METHODS

We carried out a case-control study of MPM in 472 workers insured by the Mexican Institute of Social Security, all Valley of Mexico residents, with 119 incident cases and 353 controls. Cases were histologically confirmed. Participants were questioned concerning their occupational history and sociodemographic data. Assignment to one of the four exposures was performed qualitatively by an expert hygienist. Odds ratios (ORs) and attributable risks (ARs) were calculated using a non-conditional logistic regression model.

RESULTS

A total of 80.6% of cases and 31.5% of controls had occupational exposure to asbestos. ORs were adjusted for age and gender and by exposure category, and exhibited an increase with probability of exposure as follows: 3.7(95% CI 1.3-10.4) for the likely category and 14.3(95% CI 8-26) for the certain category; AR in the group occupationally exposed to asbestos was 83.2%, and the population AR was 44%.

CONCLUSIONS

Our results show that the relationship between industrial uses of all forms of asbestos is generating an increase in mesothelioma-related diseases and deaths among Mexican workers. As a public health policy, Mexico should prohibit the use of asbestos in all production processes with the aim of controlling the epidemic and preventing the occurrence of new cases of MPM.

Lifestyle Factors, Exposures, Genetic Susceptibility, and Renal Cell Cancer Risk: A Review

Malignant kidney tumors account for approximately 2% of all new primary cancer cases diagnosed in the United States, with an estimated 30,000 cases occurring annually. Although a variety of agents, chemical and biological, have been implicated as causal agents in the development of renal cell carcinoma (RCC), the etiology remains enigmatic. The strongest association has been developed between cigarette smoking and renal cancer however consistent, positive associations between RCC and obesity, diabetes, and hypertension have also been reported. In addition, more recent investigations of familial kidney cancer syndromes indicate that a strong genetic component contributes to RCC development. Several genes have been identified through investigation of familial kidney cancer syndromes. This review article describes recent trends in RCC incidence and the currently identifiable etiological causes that account for approximately half of the RCC cases diagnoses. The remainder of this review then focuses on additional risk factors that have thus far not been well examined but may be helpful in explaining the increasing incidence trends and the geographic or racial variation observed nationally and worldwide.