Laryngeal and hypopharyngeal cancer and occupation: results of a case control-study

Hypopharyngeal cancer trends in a high-incidence region: A retrospective tertiary single center study

BACKGROUND

Hypopharyngeal cancer has the bleakest prognosis among head and neck cancers due to its extensive submucosal involvement, advanced tumor stage, and limited surgical reconstruction options. Its primary causes include alcohol consumption, tobacco use, genetic predisposition, 1` diet, and socioeconomic conditions. While squamous cell carcinoma (SCC) accounts for 95% of hypopharyngeal tumors, it remains a rare form, comprising only 3%-5% of all SCC cases in the head and neck region. Globally, Central and Eastern Europe have the highest incidence rates for males (3.9 per 100000) and the third highest for females (2.26 per 100000), underscoring the significance of this seemingly uncommon condition. In Romania, hypopharyngeal cancer ranked 24th in incidence rate, with 634 new cases in 2020.

AIM

To study the incidence, treatment and survival rates of hypopharyngeal tumor cases in a major ear, nose, throat (ENT) surgical center.

METHODS

A retrospective epidemiological clinical study was conducted on patients diagnosed and treated for hypopharyngeal cancer at the ENT department of "Carol Davila Central University Emergency Military Hospital" in Bucharest between January 2018 and August 2022. The study included 53 patients and was authorized by the Ethics Committee of Titu Maiorescu Doctoral School (Bucharest, Romania) and the Ethics Committee of Carol Davila Central University Emergency Military Hospital (Bucharest, Romania). Inclusion criteria required a positive histopathological diagnosis of hypopharyngeal cancer, tumor localization in the hypopharyngeal region, and informed consent for data usage. Exclusion criteria involved major psychiatric pathologies and disagreement for data usage. Diagnosis was based on ENT assessment, imaging reports, and laboratory data. Treatment methods were determined based on various factors. Additional tools, such as Adult Comorbidity Evaluation-27 and Karnofski Performance Status Scale, were used for risk assessment and functional capacity evaluation. Quality of life aspects were measured using the European Organisation for Reasearch and Treatment of Cancer Quality of Life Questionnaire Head and Neck-35 questionnaire.

RESULTS

Our retrospective study examined 53 patients with hypopharyngeal cancer between January 2018 and August 2022. The majority of patients were male (94.3%), with an average age at diagnosis of 62.5 years. Among the patients, 20.75% were employed, 66.03% were retired, and 9.43% were unemployed. Smoking was prevalent among 69.81% of patients, while alcohol consumption was frequent in 32.07% of cases. The tumors were mostly diagnosed at an advanced stage (stage IV) and were predominantly SCC. Comorbidities were present in 83.01% of patients, with cardiovascular diseases being the most common. Dysphagia and neck mass were the most common symptoms reported. Treatment methods included surgery, radiation therapy, and chemotherapy. A favorable treatment response was observed in 22.64% of cases, while relapse occurred in 6 cases. Follow-up data was unavailable for some patients.

CONCLUSION

In summary, our findings align with existing literature; however, we observed a higher severity.

Cancer and mortality in coal mine workers: a systematic review and meta-analysis

Coal mine workers are exposed to a number of workplace hazards which may increase the risk of cancer and mortality. We conducted a systematic review and meta-analysis to investigate cancer and mortality in coal mine workers We searched in Ovid Medline, PubMed, Embase and Web of Science databases using keywords and text words related to coal mines, cancer and mortality and identified 36 full-text articles using predefined inclusion criteria. Each study's quality was assessed using the Newcastle-Ottawa Scale. We performed random-effect meta-analyses including 21 of the identified articles evaluating cancer and/or mortality of coal mine workers. The meta-analysis showed an increased risk of all-cause mortality (SMR 1.14, 95% CI 1.00 to 1.30) and mortality from non-malignant respiratory disease (NMRD) (3.59, 95% CI 3.00 to 4.30) in cohorts with coal workers' pneumoconiosis (CWP). We found a somewhat increased risk of stomach cancer (1.11, 95% CI 0.97 to 1.35) and of mortality from NMRD (1.26, 95% CI 0.99 to 1.61) in the cohorts of coal miners with unknown CWP status. The meta-analysis also showed a decreased risk of prostate cancer and cardiovascular and cerebrovascular mortality among coal miners. This may be a result of the healthy worker effect and possible lower smoking rates, and perhaps also reflect the physically active nature of many jobs in coal mines. The meta-analysis for lung cancer did not show increased risk in coal miners with CWP (1.49, 95% CI 0.70 to 3.18) or for coal miners of unknown CWP status (1.03, 95% CI 0.91 to 1.18). Lower smoking rates in coal mine workers could explain why case-control studies where smoking was controlled for showed higher risks for lung cancer than were seen in cohort studies. Coal mine workers are at increased risk of mortality from NMRD but decreased risk of prostate cancer and cardiovascular and cerebrovascular mortality. Studies of coal mine workers need long-term follow-up to identify increased mortality and cancer incidence.

Occupational socioeconomic risk associations for head and neck cancer in Europe and South America: individual participant data analysis of pooled case-control studies within the INHANCE Consortium

BACKGROUND

The association between socioeconomic disadvantage (low education and/or income) and head and neck cancer is well established, with smoking and alcohol consumption explaining up to three-quarters of the risk. We aimed to investigate the nature of and explanations for head and neck cancer risk associated with occupational socioeconomic prestige (a perceptual measure of psychosocial status), occupational socioeconomic position and manual-work experience, and to assess the potential explanatory role of occupational exposures.

METHODS

Pooled analysis included 5818 patients with head and neck cancer (and 7326 control participants) from five studies in Europe and South America. Lifetime job histories were coded to: (1) occupational social prestige-Treiman's Standard International Occupational Prestige Scale (SIOPS); (2) occupational socioeconomic position-International Socio-Economic Index (ISEI); and (3) manual/non-manual jobs.

RESULTS

For the longest held job, adjusting for smoking, alcohol and nature of occupation, increased head and neck cancer risk estimates were observed for low SIOPS OR=1.88 (95% CI: 1.64 to 2.17), low ISEI OR=1.74 (95% CI: 1.51 to 1.99) and manual occupations OR=1.49 (95% CI: 1.35 to 1.64). Following mutual adjustment by socioeconomic exposures, risk associated with low SIOPS remained OR=1.59 (95% CI: 1.30 to 1.94).

CONCLUSIONS

These findings indicate that low occupational socioeconomic prestige, position and manual work are associated with head and neck cancer, and such risks are only partly explained by smoking, alcohol and occupational exposures. Perceptual occupational psychosocial status (SIOPS) appears to be the strongest socioeconomic factor, relative to socioeconomic position and manual/non-manual work.

Welding and the risk of head and neck cancer: the ICARE study

OBJECTIVE

To investigate the association between occupational exposure to welding and the risk of head and neck cancer in a large French population-based case-control study, the Investigation of occupational and environmental CAuses of REspiratory cancers study.

METHODS

Analyses were restricted to men (2703 controls and 1588 cases of squamous-cell carcinoma of the oral cavity, oropharynx, hypopharynx and larynx). Welding activity and potential confounders were assessed by detailed questionnaires. ORs and CIs (95% CI) were estimated by unconditional logistic regression, adjusted for age, area of residence, tobacco smoking, alcohol consumption and occupational exposure to asbestos.

RESULTS

Welding was associated with an increased risk of head and neck cancer overall (OR=1.31, 95% CI 1.03 to 1.67). The association was strongest for laryngeal cancer (OR=1.66, 95% CI 1.15 to 2.38) and the risk increased with the cumulative duration (p-trend <0.01) and the weighted duration (p-trend <0.01) of welding. A cumulative duration and a weighted duration of welding of more than 10 years were also associated with a significantly increased risk of oral cancer (OR=1.82, 95% CI 1.09 to 3.04; OR=2.10, 95% CI 0.99 to 4.45, respectively). A long duration of arc welding was associated with laryngeal cancer, whereas a long duration of spot welding was associated with oral cancer. Welding was not associated with the risk of oropharyngeal and hypopharyngeal cancer.

CONCLUSION

Our findings suggest that welding and several welding-related tasks increase the risk of laryngeal cancer and to a lesser extent oral cancer.

Laryngeal Cancer Risks in Workers Exposed to Lung Carcinogens: Exposure-Effect Analyses Using a Quantitative Job Exposure Matrix

INTRODUCTION

Various established occupational lung carcinogens are also suspected risk factors for laryngeal cancer. However, individual studies are often inadequate in size to investigate this relatively rare outcome. Other limitations include imprecise exposure assessment and inadequate adjustment for confounders.

METHODS

This study applied a quantitative job exposure matrix (SYN-JEM) for four established occupational lung carcinogens to five case-control studies within the International Head and Neck Cancer Epidemiology Consortium. We used occupational histories for 2256 laryngeal cancer cases and 7857 controls recruited from 1989 to 2007. We assigned quantitative exposure levels for asbestos, respirable crystalline silica, chromium-VI, and chromium-VI and nickel combined (to address highly correlated exposures) via SYN-JEM. We assessed effects of occupational exposure on cancer risk for males (asbestos, respirable crystalline silica, chromium-VI, and chromium-VI and nickel combined) and females (asbestos and respirable crystalline silica), adjusting for age, study, tobacco smoking, alcohol consumption, and asbestos exposure where relevant.

RESULTS

Among females, odds ratios (ORs) were increased for ever versus never exposed. Among males, P values for linear trend were <0.05 for estimated cumulative exposure (all agents) and <0.05 for exposure duration (respirable crystalline silica, chromium-VI, and chromium-VI and nickel combined); strongest associations were for asbestos at >90th percentile cumulative exposure (OR = 1.3, 95% confidence interval [CI] = 1.0, 1.6), respirable crystalline silica at 30+ years duration (OR = 1.4, 95% CI = 1.2, 1.7) and 75th-90th percentile cumulative exposure (OR = 1.4, 95% CI = 1.1, 1.8), chromium-VI at >75th percentile cumulative exposure (OR = 1.9, 95% CI = 1.2, 3.0), and chromium-VI and nickel combined at 20-29 years duration (OR = 1.5, 95% CI = 1.1, 2.2).

CONCLUSIONS

These findings support hypotheses of causal links between four lung carcinogens (asbestos, respirable crystalline silica, chromium-VI, and nickel) and laryngeal cancer.

Alachlor Use and Cancer Incidence in the Agricultural Health Study: An Updated Analysis

Background

The herbicide alachlor has been widely used in US agriculture since its introduction in 1969. Experimental animal studies show that alachlor causes tumors in vivo; however, few epidemiologic studies have examined associations with human cancer risk. We evaluated alachlor use and cancer incidence in the Agricultural Health Study, updating an earlier analysis that suggested associations with lymphohematopoietic cancers with an additional 540 142 person-years of follow-up and 5113 cancer cases.

Methods

Pesticide applicators in Iowa and North Carolina reported lifetime alachlor use at enrollment (1993-1997) and follow-up (1999-2005). Exposure was characterized by cumulative intensity-weighted days. We estimated relative risks (RRs) and 95% confidence intervals (CIs) using Poisson regression for incident cancers from enrollment through 2012(NC)/2013(IA). Models adjusted for age, tobacco, alcohol, and other pesticides. All statistical tests are two-sided.

Results

Among 49 685 applicators, 25 640 (51.6%) used alachlor, with 3534 alachlor-exposed cancers. The relative risks of laryngeal cancer (nexposed = 34) increased in the second (RR = 4.68, 95% CI = 1.95 to 11.23), third (RR = 6.04, 95% CI = 2.44 to 14.99), and fourth quartiles (RR = 7.10, 95% CI = 2.58 to 19.53) of intensity-weighted days of use compared with no use (Ptrend = .001). Risk of myeloid leukemia was elevated, though not statistically significantly so, in the fourth quartile of intensity-weighted days of use (RR = 1.82, 95% CI = 0.85 to 3.87, Ptrend = .17).

Conclusions

We observed a strong positive association with use of alachlor and laryngeal cancer and a weaker association with myeloid leukemia. The strength and robustness of the association with laryngeal cancer suggests that long-term occupational exposure to alachlor may be a risk factor for laryngeal cancer. This first report requires confirmation.

Occupations and the Risk of Head and Neck Cancer: A Pooled Analysis of the International Head and Neck Cancer Epidemiology (INHANCE) Consortium

OBJECTIVE

To investigate the associations between head and neck cancer (HNC) risk and occupations.

METHODS

We harmonized data on occupations in a pooled analysis of 8839 HNC cases and 13,730 controls in International Head and Neck Cancer Epidemiology (INHANCE) consortium. Logistic regression was used to estimate odds ratios (ORs) for associations of occupations and HNC risk. Population attributable fraction (PAF) for occupations was calculated using the formula PEC × (OR - 1)/OR.

RESULTS

Trend of increasing HNC risk was found with increasing duration of employment for many occupations, including cooks (OR = 1.36; 95% confidence interval [CI] 1.09 to 1.68), cleaners (OR = 1.38; 95% CI 1.13 to 1.69), painters (OR = 1.82; 95% CI 1.42 to 2.35). The PAF for a priori occupations was 14.5% (95% CI 7.1% to 21.9%) for HNC.

CONCLUSIONS

We found associations between certain occupations and HNC risks, including for subsites, with a duration-response relationship.

Prevalence and Occupation of Patients Presenting With Dysphonia in the United States

OBJECTIVE

Voice disorders are common conditions that may have a significant impact on patient quality of life, yet their prevalence and epidemiology are poorly documented. In this study, we estimated the prevalence, demographics, and occupation of patients with dysphonia.

METHODS

Using the Commercial and Medicare MarketScan databases of 146.7 million lives (2008-2012), the prevalence of dysphonia was estimated. Patient demographics and industry occupation were evaluated. Prevalence estimates overall and by industry were made using Medical Expenditure Panel Survey. Industry estimates were compared with US government employment statistics to assess differences between dysphonia and the general population.

RESULTS

A gradual increase in the diagnosis of dysphonia was noted from 1.3% to 1.7% of the population from 2008 to 2012, with an associated increase in the diagnosis of acute laryngitis, the largest diagnostic category. A strong correlation was present between diagnosis and age, with acute laryngitis more common in the younger populations and malignancies in older ages. Benign neoplasms were more prevalent in the service industry, with 2.6 times increased likelihood compared with the general population, and malignancies were more prevalent in the manufacturing industry, with 1.4 times increased likelihood. Almost 3 million laryngoscopies and stroboscopies were performed with $900 million in costs.

CONCLUSION

Prevalence rates of the diagnosis of dysphonia are increasing and are associated with large healthcare costs. Prevalence rates also differ somewhat between industries, and there appears to be a higher percentage of malignant neoplasms in the manufacturing industry and benign neoplasms in the service industry.

Occupational exposure to solvents and risk of head and neck cancer in women: a population-based case-control study in France

OBJECTIVE

Our objective was to investigate the association between head and neck cancer and occupational exposure to chlorinated, oxygenated and petroleum solvents in women.

METHODS

Investigation of occupational and environmental CAuses of REspiratory cancers (ICARE), a French population-based case-control study, included 296 squamous cell carcinomas of the head and neck (HNSCC) in women and 775 female controls. Lifelong occupational history was collected. Job-exposure matrices allowed to assess exposure to 5 chlorinated solvents (carbon tetrachloride; chloroform; methylene chloride; perchloroethylene; trichloroethylene), 5 petroleum solvents (benzene; special petroleum product; gasoline; white spirits and other light aromatic mixtures; diesel, fuels and kerosene) and 5 oxygenated solvents (alcohols; ketones and esters; ethylene glycol; diethyl ether; tetrahydrofuran). OR and 95% CIs, adjusted for smoking, alcohol drinking, age and geographical area, were estimated with logistic models.

RESULTS

Elevated ORs were observed among women ever exposed to perchloroethylene (OR=2.97, 95% CI 1.05 to 8.45) and trichloroethylene (OR=2.15, 95% CI 1.21 to 3.81). These ORs increased with exposure duration (OR=3.75, 95% CI 0.64 to 21.9 and OR=4.44, 95% CI 1.56 to 12.6 for 10 years or more, respectively). No significantly increased risk of HNSCC was found for occupational exposure to the other chlorinated, petroleum or oxygenated solvents.

CONCLUSIONS

These findings suggest that exposure to perchloroethylene or trichloroethylene may increase the risk of HNSCC in women. In our study, there is no clear evidence that the other studied solvents are risk factors for HNSCC.

Manuscript title: Geospatial analysis of Cancer risk and residential proximity to coal mines in Illinois

BACKGROUND

Studies have indicated a population-level association between coal mining and cancer incidence and mortality, but few studies specifically examined residential proximity to this exposure using spatial analysis. We utilized a Geographic Information Systems (GIS) approach to perform spatial and statistical analyses to test two coal mining exposure variables and their associations with cancer incidence and mortality in Illinois--the fourth highest coal producing state in the United States.

METHODS

Data included age-adjusted county-level cancer incidence and mortality for five cancers: all malignant, lung, colorectal, breast (female) and prostate. Coal mining exposure was defined by two variables: coal production group and distance-weighted exposure. Spatial analyses were performed to identify spatial clustering. Correlation and stepwise regression analyses were performed to explore the relationship between cancer incidence and mortality and coal mining exposures. Covariates considered in regression analyses included socioeconomic deprivation, former/current smoking prevalence, race, and rurality.

RESULTS

Global spatial autocorrelation indicated significant spatial clustering of incidence, mortality and aggregated coal production. Distance-weighted exposure was significantly correlated with coal production group, age-adjusted all cancer incidence and age-adjusted all cancer mortality. Regression analyses indicated an association between recent coal production and colorectal cancer incidence (p=0.009) and mortality (p=0.035) and prostate cancer mortality (p=0.047). Distance weighted exposure was associated with lung cancer incidence (p=0.004) and mortality (p<0.001), and all cancer mortality (p<0.001).

CONCLUSION

Coal production, incidence and mortality are spatially clustered in Illinois. Exposures to coal mining were associated with elevated risk of multiple cancers, most notably lung and colorectal. The environmental impact of the mining industry is substantial, and exposure of individuals residing near coal mines to known carcinogens is plausible. Future studies are needed to further elucidate the population exposure dynamics of coal mining, and should be explored using individual-level exposures and cancer outcomes.

Chemometric methods for studying the relationships between trace elements in laryngeal cancer and healthy tissues

A quick and reliable method for the evaluation and classification of two types of tissues is presented. Several chemometric methods were applied to evaluate multivariate data of the tissue samples with respect to the content of trace elements. The content of Pb, Al, Zn, Cd, Cu, Ni and Co was determined in samples of healthy and cancerous tissue obtained from 26 patients. Determination was done at milligram/kilogram level with inductively coupled plasma optical emission spectrometry (ICP-OES) and atomic absorption spectroscopy (AAS) techniques. Contents of trace metals in studied tissues are not normally distributed; however, normal distribution was confirmed for log values. There is a statistically significant difference in the content of Zn, Cd, Cu and Al (p<0.01) and Ni and Co (p<0.05) when healthy tissue is compared to cancerous one. Correlation between contents of trace elements for studied tissues was positive; the highest was found between Zn and Cu. A chemometric methodology seems to be a promising tool for classifications of the tissue samples.

Occupation and head and neck cancer risk in men: results from the ICARE study, a French population-based case-control study

OBJECTIVE

To investigate the associations between occupations and head and neck (HN) cancer risk in men.

METHODS

ICARE is a French population-based case-control study on HN cancer. Analyses included 1833 cases and 2747 controls. Complete occupational history was collected. Odds ratios (ORs) were estimated for occupations and industries ever held and according to duration of employment.

RESULTS

Elevated ORs, increasing with duration of employment, were observed for several occupations, including cleaners (OR = 1.7; 95% confidence interval [CI], 1.0 to 2.8), launderers (OR = 6.8; CI, 1.3 to 34.4), firefighters (OR = 3.9; CI, 1.4 to 11.2), several agricultural occupations, welders (OR = 1.9; CI, 1.3 to 2.8), structural metal preparers and erectors (OR = 2.1; CI, 1.2 to 3.7), rubber workers (OR = 2.0; CI, 1.0 to 3.9), several construction occupations, and material-handling equipment operators (OR = 1.8; CI, 1.1 to 2.9). Analyses by industry corroborated these findings.

CONCLUSIONS

These results confirmed the role of occupational exposures in HN cancer.

Risk of laryngeal and nasopharyngeal cancer associated with arsenic and cadmium in the Tunisian population

Chronic exposure to heavy metals has long been recognized as being capable of increasing head and neck cancer (HNC) incidence, such as laryngeal (LC) and nasopharyngeal (NPC), among exposed human populations. The aim of the present study was to evaluate the concentrations of arsenic (As) and cadmium (Cd) in the blood of 145 patients (LC and NPC) and 351 controls in order to establish a potential relationship between these factors and the occurrence of LC and NPC. Mean blood levels of As and Cd in patients (5.67 and 3.51 μg/L, respectively) were significantly higher than those of controls (1.57 and 0.74 μg/L, respectively). The blood levels of As and Cd were mostly significantly higher than those of controls (p<0.05) after controlling the other risk factors of HNC including tobacco smoking and chewing, and alcohol drinking. Cd levels in blood increase significantly with the number of occupational exposure years for patients (p<0.05). However, seafood was not found to be contributing as an exposure source. Among these risk factors, smoking (>30 pack years) and occupational exposure (>20 years) presented the most significant association with HNC (OR=10.22 and 10.38, respectively, p<0.001). Cd level in blood sample of cases that are occupationally exposed/tobacco users (smokers and chewers) were higher than that of non-occupationally exposed/nontobacco users (p<0.001). The logistic regression model illustrated that HNC (LC+NPC) was significantly associated with blood levels of As (OR=2.41, p<0.001) and Cd (OR=4.95, p<0.001).

A study on morbidity among automobile service and repair workers in an urban area of South India

INTRODUCTION

Service sector in Indian industrial growth has obtained significant numbers. Automobile service industry is one of the largest in the world with a majority of the workers in unorganized sector of the industry. This study was carried out among auto service industry workers in Vellore urban area to assess possible occupation related morbidity.

MATERIALS AND METHODS

A cross-sectional observation study was carried out among 106 automobile repair shop workers.

RESULTS

Half (47%) suffered work related stress, 32 (30.2%) reported exposure to dust, 81 (76%) to heat, and 50 (17%) to hazardous chemicals and heavy metals. More than 90% reported over exposure to petroleum products. A third reported cough for more than 2 weeks, more than a quarter reported gastrointestinal symptoms associated with work. Half of them reported musculoskeletal complaints associated with work with a quarter reporting un-intentional work place injuries. A tenth of them were found to have reduced pulmonary function on testing and nearly half had impaired sensory functions in peripheries. Reduced pulmonary function was found to be significantly associated with heavy metal exposure (P = 0.001). Peripheral neuropathy was significantly associated with years of occupation (P = 0.001), exposure to petroleum products (P = 0.03) and exposure to heavy metals (P = 0.018).

DISCUSSION

Half of the workers were unaware of health problems associated with their occupational exposures and thereby the use of personal protection is abysmally low. A very high proportion of workers had symptoms of cough, breathlessness, abdominal pain, abdominal discomfort and muscle aches. Almost a quarter of the workers had un-intentional occupational injuries in the last 6 months. Though they work in a high-risk environment with chances of fire hazard, falls and chemical exposures, none of the workshops had fire-extinguishers, first aid kits or any such safety devices.

Blood nickel and chromium levels in association with smoking and occupational exposure among head and neck cancer patients in Tunisia

Chronic exposure to chromium (Cr) and nickel (Ni) has long been recognized as being capable to increase head and neck cancer (HNC) incidence among exposed human populations. This study represents the first biomonitoring of Cr and Ni exposure in Tunisia and focuses on a possible association with HNC risk. The aim of the present study was to evaluate the concentrations of Cr and Ni in the blood of HNC patients and controls. Metals blood levels of 169 HNC patients and 351 controls were determined using a Perkin-Elmer Analyst 800 Atomic Absorption Spectrometer. Mean blood levels of Cr and Ni in HNC cases (52.15 and 111.60 μg/L, respectively) were significantly higher than those of controls (37.04 and 30.50 μg/L, respectively). Cases' blood levels of Cr and Ni were significantly higher than those of controls after controlling for the other risk factors of HNC, including smoking, shisha consumption, occupational exposure, and nearby environment (P<0.05). Among these risk factors, smoking and occupational exposure presented the most significant association with HNC (odds ratio (OR)=6.54 and 7.66, respectively, P<0.001). Cr and Ni levels in blood sample of cases and controls that are smoker/occupationally exposed were higher than that of non-smoker/non-occupationally exposed (P<0.05). Smokers who are occupationally exposed present the most significant association with HNC (OR=25.08, P<0.0001). High levels of blood Cr (OR=2.09) and high levels of blood Ni (OR=8.87) were strongly associated with HNC after other potential confounders were controlled (P=0.004 and P<0.0001, respectively). This study suggested a potential role of Cr and Ni in the mechanism of HNC development.

Population cancer risks associated with coal mining: a systematic review

Background

Coal is produced across 25 states and provides 42% of US energy. With production expected to increase 7.6% by 2035, proximate populations remain at risk of exposure to carcinogenic coal products such as silica dust and organic compounds. It is unclear if population exposure is associated with increased risk, or even which cancers have been studied in this regard.

Methods

We performed a systematic review of English-language manuscripts published since 1980 to determine if coal mining exposure was associated with increased cancer risk (incidence and mortality).

Results

Of 34 studies identified, 27 studied coal mining as an occupational exposure (coal miner cohort or as a retrospective risk factor) but only seven explored health effects in surrounding populations. Overall, risk assessments were reported for 20 cancer site categories, but their results and frequency varied considerably. Incidence and mortality risk assessments were: negative (no increase) for 12 sites; positive for 1 site; and discordant for 7 sites (e.g. lung, gastric). However, 10 sites had only a single study reporting incidence risk (4 sites had none), and 11 sites had only a single study reporting mortality risk (2 sites had none). The ecological study data were particularly meager, reporting assessments for only 9 sites. While mortality assessments were reported for each, 6 had only a single report and only 2 sites had reported incidence assessments.

Conclusions

The reported assessments are too meager, and at times contradictory, to make definitive conclusions about population cancer risk due to coal mining. However, the preponderance of this and other data support many of Hill’s criteria for causation. The paucity of data regarding population exposure and risk, the widespread geographical extent of coal mining activity, and the continuing importance of coal for US energy, warrant further studies of population exposure and risk.

Arsenic, cadmium, chromium and nickel in cancerous and healthy tissues from patients with head and neck cancer

Chronic exposure to heavy metals has long been recognized as being capable to increase head and neck cancer incidence among exposed human populations. Head and neck cancer is a significant public health issue in Tunisia. The aim of the present study was to evaluate the concentrations of As, Cd, Cr and Ni in healthy and tumor tissues of head and neck cancer patients. Metal concentrations were determined in tumor and healthy tissues of 101 head and neck cancer patients, using Atomic Absorption Spectrometry. The As, Cd, Cr, and Ni levels in tumor tissues were 3.4, 2.5, 1.3 and 1.5 times higher than those of healthy tissues (p<0.05), respectively. Tumor tissue metal levels were higher in men than in women. As and Cd levels in tumor and healthy tissue samples of patients smokers are significantly higher than those of non-smokers (p<0.05). A strong effect of cumulative smoking as expressed in the number of pack per year, and tumor tissue Cd levels were positively associated with three groups of age (<40, 51-60 and >60 years) in both never-smokers and ever-smokers (<20 and ≥20 pack per year). Healthy tissue Cd levels were negatively associated with age in those three groups of smokers. The highest Cd and Cr concentrations among both workers and non-workers were observed in tumor tissues. The Cd and Cr in tissues of farmers, bricklayers and painters were all significantly higher among the workers as compared with the non-workers group. Tissue metal levels have increased due to smoking and occupational exposure. Heavy metal exposure via tobacco smoking and occupational exposures may increase the risk of head and neck in the Tunisian population.

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.

Work in the metal industry and nasopharyngeal cancer mortality among formaldehyde-exposed workers

OBJECTIVE

To investigate further the possibility that the large nasopharyngeal cancer (NPC) mortality excess among a cohort of formaldehyde-exposed workers may be related to occupational factors external to the study plant.

METHODS

Subjects were 7345 workers employed at a plastics-producing plant (1941-1984) in Wallingford, Connecticut evaluated independently as part of a National Cancer Institute cohort study. Vital status for 98% of the cohort and cause of death for 95% of 2872 deaths were determined through 2003. Reconstructed worker exposures to formaldehyde were used to compute unlagged and lagged exposure measures. We computed standardized mortality ratios (SMRs) based on US and local county rates. In a nested case-control study we evaluated mortality risks from NPC and from all other pharyngeal cancers combined (AOPC) in relation to formaldehyde exposure while accounting for potential confounding or effect modification by smoking or external (non-Wallingford) employment. Job applications, Connecticut commercial city directories and a previous survey were used to assign subjects to three external job groups.

RESULTS

We observed no new deaths from NPC and one additional AOPC death (pharynx unspecified) yielding, respectively, SMRs of 4.43 (7 deaths, 95% CI=1.78-9.13) and 1.71 (16 deaths, 95% CI=1.01-2.72). Five of seven NPC cases worked in silver smithing (including brass plating and other jobs related to silver or brass) or other metal work (including steel working and welding), and this type of work was relatively rare in the remaining study population (OR=14.41, 95% CI=1.08-82.1). For AOPC, we found a moderate increase in risk for other metal work (OR=1.40, 95% CI=.31-5.1). Interaction models suggested that NPC and AOPC risks were not elevated in subjects exposed only to formaldehyde.

CONCLUSIONS

The results of our nested case-control study suggest that the large nasopharyngeal cancer mortality excess in the Wallingford cohort may not be due to formaldehyde exposure, but rather reflects the influence of external employment in the ferrous and non-ferrous metal industries of the local area that entailed possible exposures to several suspected risk factors for upper respiratory system cancer (e.g., sulfuric acid mists, mineral acid, metal dusts and heat). Our findings may also help to explain why the associations with formaldehyde and nasopharyngeal cancer reported in the 1994 update of the 10-plant NCI formaldehyde cohort study were unique to the Wallingford plant (Plant 1 in NCI study). Further updates of the NCI formaldehyde cohort study should include co-exposure data on silver smithing and other metal work for all study plants to help explain the unique findings for nasopharyngeal cancer in Plant 1 compared with the other nine plants.

Riscos ocupacionais para o câncer de laringe: um estudo caso-controle

O tabagismo e o consumo de álcool são os fatores de risco mais bem estabelecidos para o câncer de laringe. Com relação aos fatores ocupacionais, o único carcinógeno estabelecido é a exposição a névoas de ácidos inorgânicos fortes. Entretanto, asbesto, pesticidas, tintas, gases de combustão de gasolina e diesel e poeiras, entre outros, aparecem na literatura como agentes ocupacionais que aumentam o risco de câncer de laringe. Um estudo caso-controle de base hospitalar foi conduzido para investigar fatores de risco ocupacionais para câncer de laringe. Foram coletadas informações detalhadas sobre tabagismo, consumo de álcool e história ocupacional de 122 casos de câncer de laringe e 187 controles pareados por freqüência (segundo sexo e idade). Encontrou-se risco aumentado de câncer de laringe nos indivíduos com exposição à sílica cristalina livre respirável (OR = 1,83; IC95%: 1,00-3,36), à fuligem (de carvão mineral, coque, madeira, óleo combustível) (OR = 1,78; IC95%: 1,03-3,03), a fumos em geral (OR = 2,55; IC95%: 1,14-5,67) e a animais vivos (OR = 1,80; IC95%: 1,02-3,19).

Hormonal markers of aging in men with laryngeal carcinoma

BACKGROUND

Cancer of the larynx, a frequent neoplasm in older people, occurs several times more often in men than in women. Surprisingly, the highest incidence of the disease is observed in the period in which concentrations of a number of hormones (eg, androgens, growth hormone) decrease. Our objective was to look for differences in hormonal markers of aging between men with laryngeal carcinoma and healthy control subjects.

METHODS

Seventy-eight men with cancer of the larynx and 51 healthy age-matched controls were recruited for the study. In each of the examined men, serum concentrations of total testosterone, free testosterone, dihydrotestosterone, dehydroepiandrosterone sulfate, steroid-hormone binding globulin, estradiol, and insulin-like growth factor type 1 (IGF-1) were determined.

RESULTS

Men with laryngeal carcinoma had lower serum concentrations of IGF-1 (136 +/- 75 vs 318 +/- 141 ng/mL, p < .000001), lower free testosterone (11.95 +/- 5.38 vs 15.48 +/- 4.96 pg/mL, p < .001), and lower dihydrotestosterone/total testosterone ratio (0.07 +/- 0.06 vs 0.09 +/- 0.04, p < .05) than healthy controls had.

CONCLUSIONS

Somatopause seems to be more evident in men with laryngeal carcinoma than in age-matched controls. In our observation, low concentration of IGF-1 predicted the presence of laryngeal carcinoma more than low concentration of free testosterone did.

Smoking, alcohol drinking and cancer risk for various sites of the larynx and hypopharynx. A case–control study in France

The aim of this work was to study the effects of alcohol and tobacco consumption on laryngeal and hypopharyngeal cancer and to compare these across subsites (glottis, supraglottis, epilarynx, hypopharynx). Data from a hospital-based case-control study including 504 male cases (105 glottic cancers, 80 supraglottic cancers, 97 epilaryngeal cancers and 201 hypopharyngeal cancers) and 242 male controls with non-respiratory cancers were used for this analysis. Information about sociodemographic characteristics, detailed alcohol and tobacco consumption was collected through face-to-face interviews. Statistical analysis used logistic regression, and subsites were compared with polytomous logistic regressions. The risk of laryngeal and hypopharyngeal cancer increased with tobacco (duration and amount) and alcohol consumption; the effect of both agents was multiplicative. From the lowest to the highest consumption level, odds ratios ranged from 1.4 to 5.9 among regular drinkers and from 3 to 44 among current smokers. Risks among ex-smokers were approximately one-third of those for current smokers. Slightly elevated odds ratios were associated with consumption of black tobacco (OR=1.2) and hand-rolled cigarettes (OR=1.2). The risk of cancer was not clearly associated with the type of alcoholic beverage. Subsites did not differ significantly according to tobacco smoking, but differed according to alcohol consumption, with a significantly higher increased risk for hypopharyngeal than for glottic and supraglottic cancers.

Critical review of the epidemiological literature on occupational exposure to perchloroethylene and cancer

OBJECTIVES

Of an estimated 500,000 workers in the USA potentially exposed to perchloroethylene (PCE), the largest share is employed in the dry-cleaning industry. PCE, a non-flammable solvent, has commercial applications as a chemical intermediate, metal degreaser and, since the 1950s, primary solvent in the dry-cleaning industry. The International Agency for Research on Cancer (IARC) currently finds sufficient evidence to designate PCE as carcinogenic in animals, with limited evidence in humans. With regard to occupational exposure through dry-cleaning, PCE is considered to be possibly carcinogenic to humans. This review was conducted to assess the current epidemiological literature on PCE and specific cancers.

METHODS

A comprehensive search was conducted to identify all available epidemiological literature pertaining to the carcinogenic effects of PCE. Forty-four papers that provided reasonable data on up to 17 cancer sites were critically reviewed in the context of the available background literature for each cancer site and were assessed on the basis of specified methodological and scientific quality criteria.

RESULTS

While all the epidemiological studies selected for review investigated similar exposure-health outcome relationships, there was a broad diversity of proxy measurements of exposure to PCE, as well as numerous specific cancer outcomes of interest. The widespread lack of valid exposure measurements or other adequate indicators of potential for exposure were consistent limitations. We found no evidence of an association between breast, prostate, skin or brain cancer and exposure to PCE. A relationship between PCE and cancer of the following sites was considered unlikely: oral cavity, liver, pancreas, cervix lung. Scientific evidence was inadequate for laryngeal, kidney, esophageal and bladder cancers.

CONCLUSIONS

The current epidemiological evidence does not support a conclusion that occupational exposure to PCE is a risk factor for cancer of any specific site. Priority areas in which additional data are most needed include cancers of the esophagus and bladder.

Sugarcane farming, occupational solvent exposures, and the risk of oral cancer in Puerto Rico

The work history information from a population-based case-control study conducted in Puerto Rico was analyzed using a job exposure matrix to investigate the relationship between occupational exposures and cancers of the oral cavity or pharynx. After adjustment for age, alcohol, smoking, and residence in a logistic model, the risk for cancer of the oral cavity, but not the pharynx, was significantly elevated among farm workers in the sugarcane industry (OR = 4.4, 95% CI = 1.4-13.6). An exposure-response trend was seen for cumulative exposure to solvents, with an OR = 3.2 (95% CI = 0.8-12.6) in the highest exposure category. The overall contribution to the risk of cancer of the oral cavity or pharynx associated with occupational exposures in Puerto Rico appears to be small, however, the elevated risks were seen among sugarcane farmers and subjects with high cumulative exposure to solvents.

Laryngeal and hypopharyngeal cancers and occupational exposure to formaldehyde and various dusts: a case-control study in France

OBJECTIVES

A case-control study was conducted in France to assess possible associations between occupational exposures and squamous cell carcinomas of the larynx and hypopharynx.

METHODS

The study was restricted to men, and included 201 hypopharyngeal cancers, 296 laryngeal cancers, and 296 controls (patients with other tumour sites). Detailed information on smoking, alcohol consumption, and lifetime occupational history was collected. Occupational exposure to seven substances (formaldehyde, leather dust, wood dust, flour dust, coal dust, silica dust, and textile dust) was assessed with a job exposure matrix. Exposure variables used in the analysis were probability, duration, and cumulative level of exposure. Odds ratios (ORs) with their 95% confidence intervals (95% CIs) were estimated by unconditional logistic regression, and were adjusted for major confounding factors (age, smoking, alcohol, and when relevant other occupational exposures).

RESULTS

Hypopharyngeal cancer was found to be associated with exposure to coal dust (OR 2.31, 95% CI 1.21 to 4.40), with a significant rise in risk with probability (p<0.005 for trend) and level (p<0.007 for trend) of exposure. Exposure to coal dust was also associated with an increased risk of laryngeal cancer (OR 1.67, 95% CI 0.92 to 3.02), but no dose-response pattern was found. A significant relation, limited to hypopharyngeal cancer, was found with the probability of exposure to formaldehyde (p<0.005 for trend), with a fourfold risk for the highest category (OR 3.78, 95% CI 1.50 to 9.49). When subjects exposed to formaldehyde with a low probability were excluded, the risk also increased with duration (p<0.04) and cumulative level of exposure (p<0.14). No significant association was found for any other substance.

CONCLUSION

These results indicate that exposure to formaldehyde and coal dust may increase the risk of hypopharyngeal cancer.

Statistical issues in the analysis of disease mapping data

In this paper we discuss a number of issues that are pertinent to the analysis of disease mapping data. As an illustrative example we consider the mapping of larynx cancer across electoral wards in the North West Thames region of the U.K. Bayesian hierarchical models are now frequently employed to carry out such mapping. In a typical situation, a three-stage hierarchical model is specified in which the data are modelled as a function of area-specific relative risks at stage one; the collection of relative risks across the study region are modelled at stage two; and at stage three prior distributions are assigned to parameters of the stage two distribution. Such models allow area-specific disease relative risks to be 'smoothed' towards global and/or local mean levels across the study region. However, these models contain many structural and functional assumptions at different levels of the hierarchy; we aim to discuss some of these assumptions and illustrate their sensitivity. When relative risks are the endpoint of interest, it is common practice to assume that, for each of the age-sex strata of a particular area, there is a common multiplier (the relative risk) acting upon each of the stratum-specific risks in that area; we will examine this proportionality assumption. We also consider the choices of models and priors at stages two and three of the hierarchy, the effect of outlying areas, and an assessment of the level of smoothing that is being carried out. For inference, we concentrate on the description of the spatial variability in relative risks and on the association between the relative risks of larynx cancer and an area-level measure of socio-economic status.

Laryngeal and hypopharyngeal cancer and occupational exposure to asbestos and man-made vitreous fibers: results of a case-control study

BACKGROUND

The data from a case-control study performed in France between 1989 and 1991 were used to test whether exposure to either asbestos or to man-made vitreous fibers (MMVF) is a risk factor for cancer of the larynx or the hypopharynx.

METHODS

This study involved 315 incident cases of laryngeal cancer, 206 cases of hypopharyngeal cancer, and 305 hospital-based controls with other types of cancer, all recruited in 15 hospitals in six French cities. The subjects' past occupational exposure to asbestos and to four types of MMVF (mineral wool, refractory ceramic fibers, glass filaments, and microfibers) was evaluated based on their job history, with the aid of a job-exposure matrix. Odds ratios were calculated with unconditional logistic regression, with adjustment for smoking and drinking levels.

RESULTS

Exposure to asbestos resulted in a significant increase in the risk of hypopharyngeal cancer (OR = 1.80, 95% CI: 1.08-2.99) and a nonsignificant increase in the risk of laryngeal cancer (OR = 1.24, 95% CI: 0.83-1.90). Risk was highest for the epilarynx (highest cumulative level of exposure: OR = 2.22, 95% CI: 1.05-4.71). Exposure to mineral wools was of borderline significance for the risk of hypopharyngeal cancer (OR = 1.55, 95% CI: 0.99-2.41), and nonsignificantly associated with the risk of laryngeal cancer (OR-1.33, 95% CI: 0.91-1.95). The risk was again highest for the epilarynx (OR = 1.85, 95% CI: 1.08-3.17). No significant results were observed for the other MMVF.

CONCLUSIONS

These results suggest that asbestos exposure increases the risk of epilaryngeal and hypopharyngeal cancers. It is difficult to reach a conclusion about the effects of mineral wools, because nearly all the exposed subjects were also exposed to asbestos. The possible effects of other MMVF were difficult to assess in this study, because of the paucity of exposed subjects.