Occupational exposure and laryngeal and hypopharyngeal cancer risk in central and eastern Europe

Meta-Analysis of the Relationship Between Occupational/Environmental Exposure to Wood Dust and Laryngeal Cancer

OBJECTIVE

Wood dust is a human carcinogen. However, studies examining the relationship between wood dust exposure and laryngeal cancer have yielded inconsistent findings. Therefore, we systematically reviewed relevant studies examining the relationship between wood dust exposure and laryngeal cancer development, followed by a meta-analysis.

METHODS

Publications in the following databases were searched: PubMed, Medline, Embase, Cochrane Library, and China National Knowledge Infrastructure (CNKI). The Newcastle-Ottawa scale was used to evaluate the study quality. A random-effects model was used for the meta-analysis.

RESULTS

Eighteen case-control studies and one cohort study, involving a total of 4426 patients with laryngeal cancer and 319,129 control participants, were identified. The association between occupational/environmental exposure to wood dust and laryngeal cancer, if any, was unclear (adjusted combined OR: 1.11; 95% CI: 0.94-1.31). However, subgroup analyses according to the number of cases, geographic region, publication year, and follow-up duration revealed correlations between wood dust exposure correlated and laryngeal cancer, as follows: number of cases > 200 (OR: 1.14; 95% CI: 1.01-1.25 [n = 10]); studies conducted in the US (OR: 1.21; 95% CI: 1.07-1.37 [n = 5]); follow-up time > 5 years (OR: 1.19; 95% CI: 1.07-1.32 [n = 10]); and publication after the year 2000 (OR: 1.15; 95% CI: 1.04-1.28 [n = 8]). A high heterogeneity in the results was observed (I2 = 42.5%, p = 0.024). The results were stable, and no publication bias existed, according to sensitivity analysis.

CONCLUSIONS

This meta-analysis suggests that wood dust exposure is associated with laryngeal cancer. Additional large-scale studies are warranted to clarify the relationship between wood dust exposure and laryngeal cancer.

Occupational exposure to diesel exhaust and head and neck cancer: a systematic review and meta-analysis of cohort studies

Exposure to diesel exhaust (DE) and other fossil fuels in the workplace can cause several health effects including cancer. We conducted a systematic review and meta-analysis of cohort studies examining the association between occupational DE exposure and the risk of head and neck cancer (HNC), including cancer of the oral cavity, pharynx and larynx. We included cohort studies mentioned in the Monograph of the International Agency for Research on Cancer, 2014, on DE. Forest plots of relative risk (RR) were constructed for HNC overall and its anatomical subtypes. A random-effects model was used to address heterogeneity between studies. Fifteen articles were included after removing duplicates and irrelevant reports. The summary RR for DE exposure was 1.08 [95% confidence interval (CI) = 1.01-1.17, P heterogeneity = <0.001] for HNC overall, 0.98 (95% CI = 0.87-1.11) for oral cavity, 1.05 (95% CI = 0.77-1.43) for pharyngeal, 1.15 (95% CI = 0.96-1.38) for oral cavity and pharyngeal combined, and 1.13 (95% CI = 1.03-1.24) for laryngeal cancer. There were elevated RRs for incidence studies of HNC (RR = 1.13; 95% CI = 1.05-1.22, P  = 0.001), European studies (RR = 1.13; 95% CI = 1.05-1.23, P  = 0.001), and female studies (RR = 1.77; 95% CI = 1.31-2.39, P  = 0.003). Our study suggested an association between occupational DE exposure and the risk of HNC, particularly laryngeal cancer. Although residual confounding cannot be ruled out, our results support the importance of controlling occupational DE exposure.

Exposome and unhealthy aging: environmental drivers from air pollution to occupational exposures

The aging population worldwide is facing a significant increase in age-related non-communicable diseases, including cardiovascular and brain pathologies. This comprehensive review paper delves into the impact of the exposome, which encompasses the totality of environmental exposures, on unhealthy aging. It explores how environmental factors contribute to the acceleration of aging processes, increase biological age, and facilitate the development and progression of a wide range of age-associated diseases. The impact of environmental factors on cognitive health and the development of chronic age-related diseases affecting the cardiovascular system and central nervous system is discussed, with a specific focus on Alzheimer's disease, Parkinson's disease, stroke, small vessel disease, and vascular cognitive impairment (VCI). Aging is a major risk factor for these diseases. Their pathogenesis involves cellular and molecular mechanisms of aging such as increased oxidative stress, impaired mitochondrial function, DNA damage, and inflammation and is influenced by environmental factors. Environmental toxicants, including ambient particulate matter, pesticides, heavy metals, and organic solvents, have been identified as significant contributors to cardiovascular and brain aging disorders. These toxicants can inflict both macro- and microvascular damage and many of them can also cross the blood-brain barrier, inducing neurotoxic effects, neuroinflammation, and neuronal dysfunction. In conclusion, environmental factors play a critical role in modulating cardiovascular and brain aging. A deeper understanding of how environmental toxicants exacerbate aging processes and contribute to the pathogenesis of neurodegenerative diseases, VCI, and dementia is crucial for the development of preventive strategies and interventions to promote cardiovascular, cerebrovascular, and brain health. By mitigating exposure to harmful environmental factors and promoting healthy aging, we can strive to reduce the burden of age-related cardiovascular and brain pathologies in the aging population.

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.

Evaluating the Sub-Acute Toxicity of Formaldehyde Fumes in an In Vitro Human Airway Epithelial Tissue Model

Formaldehyde (FA) is an irritating, highly reactive aldehyde that is widely regarded as an asthmagen. In addition to its use in industrial applications and being a product of combustion reaction and endogenous metabolism, FDA-regulated products may contain FA or release FA fumes that present toxicity risks for both patients and healthcare workers. Exposure to airborne FA is associated with nasal neoplastic lesions in both animals and humans. It is classified as a Group 1 carcinogen by International Agency for Research on Cancer (IARC) based on the increased incidence of cancer in animals and a known human carcinogen in the Report on Carcinogens by National Toxicology Program (NTP). Herein, we systematically evaluated the tissue responses to FA fumes in an in vitro human air-liquid-interface (ALI) airway tissue model. Cultures were exposed at the air interface to 7.5, 15, and 30 ppm of FA fumes 4 h per day for 5 consecutive days. Exposure to 30 ppm of FA induced sustained oxidative stress, along with functional changes in ciliated and goblet cells as well as possible squamous differentiation. Furthermore, secretion of the proinflammatory cytokines, IL-1β, IL-2, IL-8, GM-CSF, TNF-a and IFN-γ, was induced by repeated exposures to FA fumes. Expression of MMP-1, MMP-3, MMP-7, MMP-10, MMP-12, and MMP-13 was downregulated at the end of the 5-day exposure. Although DNA-damage was not detected by the comet assay, FA exposures downregulated the DNA repair enzymes MGMT and FANCD2, suggesting its possible interference in the DNA repair capacity. Overall, a general concordance was observed between our in vitro responses to FA fume exposures and the reported in vivo toxicity of FA. Our findings provide further evidence supporting the application of the ALI airway system as a potential in vitro alternative for screening and evaluating the respiratory toxicity of inhaled substances.

Association of SIRT1 single gene nucleotide polymorphisms and serum SIRT1 levels with laryngeal squamous cell carcinoma patient survival rate

BACKGROUND

SIRT1 is a multifunctional protein, possibly essential in tumorigenesis pathways, which can act both as a tumor promoter and tumor suppressor depending on the oncogenes, specific to particular tumors. Pathogenesis of laryngeal cancer is multifactorial and the association of SIRT1 expression with the clinical characteristics and prognosis of LSCC has not been fully identified.

OBJECTIVES

The study aimed to evaluate associations between single gene nucleotide polymorphisms (SNPs) of SIRT1 (rs3818292, rs3758391, and rs7895833), serum SIRT1 levels, and 5-year survival rate in patients with laryngeal squamous cell carcinoma (LSCC).

METHODS

The study involved 302 patients with LSCC and 409 healthy control subjects. The genotyping of SNPs was performed using RT-PCR, and serum SIRT1 levels were determined by the ELISA method.

RESULTS

Our study found significant differences in genotype distributions of SIRT1 rs3758391 polymorphisms between the study groups. SIRT1 rs3758391 T/T genotype was associated with the increased LSCC development odds (OR = 1.960 95% CI = 1.028-3.737; p= 0.041). Carriers of SIRT1 rs3758391 T/T genotype had statistically significantly increased odds of LSCC development into advanced stages under the codominant and recessive genetic models (OR = 2.387 95% CI = 1.091-5.222; p= 0.029 and OR = 2.287 95% CI = 1.070-4.888; p= 0.033, respectively). There were no statistically significant differences in serum SIRT1 levels between the LSCC and control groups. However, LSCC patients with SIRT1 rs3818292 AG genotype demonstrated a tendency to significantly lower SIRT1 serum levels than controls (p= 0.034). No statistically significant associations between SIRT1 (rs3818292, rs3758391, and rs7895833) SNPs and the 5-year survival rate of LSCC patients were found.

CONCLUSION

The present study indicated a statistically significant association between the SIRT1 rs3758391 T/T genotype and increased LSCC development odds. LSCC patients with SIRT1 rs3818292 AG genotype showed a tendency to manifest with lower SIRT1 serum levels. No associations between SIRT1 SNPs and the 5-year survival rate of LSCC patients were detected.

The Carcinogenic Effects of Formaldehyde Occupational Exposure: A Systematic Review

BACKGROUND

Formaldehyde, classified as a carcinogen in 2004, as of today is widely used in many work activities. From its classification, further studies were performed to evaluate its carcinogenicity. The aim of the systematic review is to update the evidence on occupational exposure to formaldehyde and cancer onset.

METHODS

The review, in accordance with the PRISMA statement, includes articles in English reporting original results of studies conducted on workers exposed to formaldehyde, considering all types of cancer, published from 1 January 2000 to 30 July 2021 and selected from the Pubmed and Scopus databases. The studies' quality was assessed by the Newcastle-Ottawa Scale.

RESULTS

A total of 21 articles were included, conducted in different European, American, and Asian countries. The most investigated occupational areas are those characterized by a deliberate use of formaldehyde. Some studies evaluated all types of cancer, whereas others focused on specific sites such as thyroid and respiratory, lymphohematopoietic, or central nervous systems. The results showed weak associations with lung cancer, nasopharyngeal cancer, leukemia, and non-Hodgkin's lymphoma.

CONCLUSIONS

The results demonstrate the need for further original studies carried out on representative samples of workers exposed to measured levels of FA. These studies should be designed to reduce the bias due to co-exposure to other carcinogens.

Exposure to cadmium and head and neck cancers: a meta-analysis of observational studies

Cadmium (Cd) is a widespread environmental pollutant. A number of observational studies have reported that Cd might be a cause of nasopharyngeal (NPC), pharyngeal (PC), or laryngeal cancers (LC). In this study evidence about the relation of Cd and NPC, PC, and LC has been summarized. A literature review was conducted until 20 June 2020 in PubMed, Ovid, Scopus, Web of Science and Google scholar databases to investigate the epidemiologic evidence for the relation between cadmium exposure and cancers of the nasopharynx, pharynx, and larynx. Ten articles were selected after careful screening of retrieved studies. All of these studies obtained a Newcastle-Ottawa Scale (NOS) quality score from 6 to 8. Due to high heterogeneity, in all analyses, random effect was used. The pooled results showed that cadmium levels in NPC (standard mean difference (SMD=0.55; 95% CI=0.20, 0.89; p=0.002) and PC (SMD=9.79; 95% CI=0.62, 18.96; p=0.036) patients/tissues were significantly higher than their controls. But cadmium levels were not significantly different between LC cases/tissues and their controls. (SMD=-0.05; 95% CI=-0.99, 0.89; p=0.921). Exposure to cadmium is likely to cause nasopharyngeal and pharyngeal cancer.

Epidemiological Analysis of 1234 Cases of Laryngeal Cancer in Shanxi Province, China

Background

Laryngeal cancer is a common malignancy of the head and neck, especially in northern China, including Shanxi province. This study intends to describe the epidemiological characteristics of laryngeal cancer in Shanxi Province, China, in order to support prevention and treatment efforts.

Methods

Retrospective analysis of the medical records of patients diagnosed with laryngeal cancer in hospitals in Shanxi Province from 2008 to 2012.

Results

The average annual incidence rate of laryngeal cancer in Shanxi province from 2008 to 2012 was 0.70/10⁵, the Chinese population standardized incidence rate was 0.57/10⁵ and the world population standardized incidence rate was 0.60/10⁵. The city with the highest incidence of laryngeal cancer in Shanxi Province is Taiyuan, followed by Yangquan, and the lowest incidence are Yuncheng and Jincheng. The cases included 723 farmers (58.6%), 338 workers (27.4%), 95 government cadres (7.7%), 35 unemployed individuals (2.8%), 30 teachers (2.4%) and 13 individuals with other occupations (1.1%). The incidence of laryngeal cancer in rural areas was 0.78/10⁵, while urban areas was 0.60/10⁵. Of 1006 patients with smoking and drinking status reported, there were 238 both smoking and drinking (23.7%), 491 only smoking but not drinking (48.8%), 4 only drinking but not smoking (0.4%), 273 both not smoking and not drinking (27.1%) (P<0.001), and there were 695 males smoking (95.3%), 34 females smoking (4.7%) (P<0.001). Of 879 patients for whom the primary cancer location was known, 406 cases (46.2%) were supraglottic and 428 cases (48.7%) were glottic. Among 1009 patients with known pathological classification, the vast majority had squamous cell carcinoma (992 cases, 98.3%).

Conclusions

To sum up, the incidence of laryngeal cancer in Shanxi Province exhibited a relatively stable trend from 2008 to 2012, and the incidence is higher in men than in women in all years. The high percentage of smokers in this study underscores the importance of smoking as a risk factor for laryngeal cancer, whereas rates of drinking did not appear to be linked. Incidence of laryngeal cancer was higher in rural areas than in urban areas, a pattern that differs from other regions of China and internationally.

Human Papillomavirus Infection in Head and Neck Squamous Cell Carcinomas: Transcriptional Triggers and Changed Disease Patterns

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of cancers. Collectively, HNSCC ranks sixth in incidence rate worldwide. Apart from classical risk factors like tobacco and alcohol, infection of human papillomavirus (HPV) is emerging as a discrete risk factor for HNSCC. HPV-positive HNSCC represent a distinct group of diseases that differ in their clinical presentation. These lesions are well-differentiated, occur at an early age, and have better prognosis. Epidemiological studies have demonstrated a specific increase in the proportions of the HPV-positive HNSCC. HPV-positive and HPV-negative HNSCC lesions display different disease progression and clinical response. For tumorigenic-transformation, HPV essentially requires a permissive cellular environment and host cell factors for induction of viral transcription. As the spectrum of host factors is independent of HPV infection at the time of viral entry, presumably entry of HPV only selects host cells that are permissive to establishment of HPV infection. Growing evidence suggest that HPV plays a more active role in a subset of HNSCC, where they are transcriptionally-active. A variety of factors provide a favorable environment for HPV to become transcriptionally-active. The most notable are the set of transcription factors that have direct binding sites on the viral genome. As HPV does not have its own transcription machinery, it is fully dependent on host transcription factors to complete the life cycle. Here, we review and evaluate the current evidence on level of a subset of host transcription factors that influence viral genome, directly or indirectly, in HNSCC. Since many of these transcription factors can independently promote carcinogenesis, the composition of HPV permissive transcription factors in a tumor can serve as a surrogate marker of a separate molecularly-distinct class of HNSCC lesions including those cases, where HPV could not get a chance to infect but may manifest better prognosis.

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.

Incidence and mortality of laryngeal cancer in China, 2015

Objective

Using data from cancer registries to estimate laryngeal cancer incidence and mortality in China, 2015.

Methods

Data submitted from 501 cancer registries were checked and evaluated according to the criteria of data quality control and 368 registries’ data were qualified for the final analysis. Data were stratified by area (urban/rural), sex, age group and combined with national population data to estimate laryngeal cancer incidence and mortality in China, 2015. China population census in 2000 and Segi’s population were used for age-standardized.

Results

The percentage of cases morphological verified (MV%) of laryngeal cancer was 74.18%. The percentage of death certificate-only cases (DCO%) was 2.10%. And the mortality to incidence (M/I) ratio was 0.55. About 25,300 new cases of laryngeal cancer were diagnosed in 2015 and 13,700 deaths were reported. The crude rate of laryngeal cancer was 1.84 per 100,000 (males and females were 3.20 and 0.42 per 100,000, respectively). Age-standardized incidence rates by Chinese standard population (ASIRC) and by world standard population (ASIRW) were 1.18 and 1.19 per 100,000, respectively. The cumulative incidence rate (0−74 years old) was 0.15%. The crude mortality rate was 1.00 per 100,000. Age-standardized mortality rates by Chinese standard population (ASMRC) and by world standard population (ASMRW) were 0.61 and 0.61 per 100,000, respectively, with the cumulative rate (0−74 years old) was 0.07%. Incidence and mortality of laryngeal cancer in males were higher than those in females. And the rates in urban areas were higher than those in rural areas.

Conclusions

The incidence and mortality of laryngeal cancer in China were low. And the rates were significantly higher in males than in females. Risk factor control and targeted prevention should be strengthened.

Human Papillomavirus Infection in Head and Neck Squamous Cell Carcinomas: Transcriptional Triggers and Changed Disease Patterns

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of cancers. Collectively, HNSCC ranks sixth in incidence rate worldwide. Apart from classical risk factors like tobacco and alcohol, infection of human papillomavirus (HPV) is emerging as a discrete risk factor for HNSCC. HPV-positive HNSCC represent a distinct group of diseases that differ in their clinical presentation. These lesions are well-differentiated, occur at an early age, and have better prognosis. Epidemiological studies have demonstrated a specific increase in the proportions of the HPV-positive HNSCC. HPV-positive and HPV-negative HNSCC lesions display different disease progression and clinical response. For tumorigenic-transformation, HPV essentially requires a permissive cellular environment and host cell factors for induction of viral transcription. As the spectrum of host factors is independent of HPV infection at the time of viral entry, presumably entry of HPV only selects host cells that are permissive to establishment of HPV infection. Growing evidence suggest that HPV plays a more active role in a subset of HNSCC, where they are transcriptionally-active. A variety of factors provide a favorable environment for HPV to become transcriptionally-active. The most notable are the set of transcription factors that have direct binding sites on the viral genome. As HPV does not have its own transcription machinery, it is fully dependent on host transcription factors to complete the life cycle. Here, we review and evaluate the current evidence on level of a subset of host transcription factors that influence viral genome, directly or indirectly, in HNSCC. Since many of these transcription factors can independently promote carcinogenesis, the composition of HPV permissive transcription factors in a tumor can serve as a surrogate marker of a separate molecularly-distinct class of HNSCC lesions including those cases, where HPV could not get a chance to infect but may manifest better prognosis.

Epithelial cell transforming sequence 2 expression is associated with the progression of laryngeal squamous cell carcinoma

Epithelial cell transforming sequence 2 (ECT2) is a guanine nucleotide exchange factor and its expression is associated with the development of malignant tumor types. However, to the best of our knowledge, there is no information on the role of ECT2 in the development and progression of laryngeal squamous cell carcinoma (LSCC). The present study aimed at investigating the expression pattern and potential role of ECT2 in the development and progression of LSCC. The expression of ECT2 in 81 pairs of LSCC and adjacent non-tumor tissues was characterized by immunohistochemistry and reverse transcription-quantitative polymerase chain reaction. ECT2 expression was upregulated in LSCC tissues and associated significantly with poor differentiation, higher stages, lymph node metastasis and poor survival in the sample population. The relative expression levels of ECT2 mRNA transcripts were correlated with the intensity of anti-ECT2 staining in 25 ECT2+LSCC specimens selected randomly. These results indicated that ECT2 expression was crucial for the progression of LSCC and may serve as a biomarker for the diagnosis and prognosis of LSCC.

Pepsin promotes IL-8 signaling-induced epithelial-mesenchymal transition in laryngeal carcinoma

Background

Laryngopharyngeal reflux (LPR), with its increasing morbidity, is attracting considerable attention. In recent years, the causal role between LPR and laryngeal carcinoma has been debated. The main harmful component of LPR is pepsin, which has been shown to induce mucosal inflammation by damaging the mucous membrane. Thus, pepsin is linked to an increased risk of laryngeal carcinoma, although the potential mechanism remains largely unknown.

Methods

The human laryngeal carcinoma cell lines Hep-2 and Tu212 were exposed to different pepsin concentrations and the morphology, proliferation, migration, secretion of inflammatory cytokines, and epithelial–mesenchymal transition (EMT) of the cells were assessed. To evaluate whether interleukin-8 (IL-8) had a causal relationship with pepsin and EMT, an IL-8 inhibitor was used to suppress IL-8 secretion during pepsin exposure and the expression of EMT markers, cell proliferation, and migration were analyzed.

Results

Pepsin promoted proliferation, colony formation, migration, and IL-8 secretion of Hep-2 and Tu212 cells in vitro. Furthermore, increased pepsin concentrations changed the morphology of Hep-2 and Tu212 cells; levels of the epithelial marker E-cadherin were reduced and those of mesenchymal markers vimentin and β-catenin and the transcription factors snail and slug were elevated. A similar effect was observed in laryngeal carcinoma tissues using immunohistochemistry. IL-8 level was reduced and EMT was restored when pepsin was inhibited by pepstatin. EMT was weakened after exposure to the IL-8 inhibitor, with significant reduction in pepsin-induced cell proliferation and migration.

Conclusions

Pepsin may induce EMT in laryngeal carcinoma through the IL-8 signaling pathway, which indicates that it has potential role in enhancing cell proliferation and metastasis of laryngeal carcinoma.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0772-7) contains supplementary material, which is available to authorized users.

Variation in Nordic Work-Related Cancer Risks after Adjustment for Alcohol and Tobacco

Background: Alcohol and tobacco strongly increases the risk of cancers of the tongue, mouth, pharynx, larynx, and oesophagus, and are also established risk factors for cancer of the liver, colon, and rectum. It is well documented that these habits are unequally distributed among occupational groups. Most occupational cohort studies lack information on these potentially important confounders, and may therefore be prone to bias. Aim: The aim of the study is to present Nordic standardized incidence ratios (SIRs) for alcohol and tobacco related cancer by occupation, after adjustment for alcohol and tobacco, and to compare to the unadjusted SIRs. Material and Methods: The study is based on the Nordic Occupational Cancer (NOCCA) database. We used confirmatory factor analysis models for simultaneous analysis of the cancer sites related to alcohol and tobacco, to obtain factors that allow for computation of adjusted expected numbers from the reference rates. We then calculated adjusted SIRs for the relevant cancer sites for each occupation. Results: For some occupations and cancers, the changes of risk estimates were striking, from significantly high to significantly low and vice versa. Among Nordic farmers, unadjusted SIRs for cancer of the mouth and oesophagus were 0.56 (95% confidence interval (CI) 0.51⁻0.61) and 0.67 (CI 0.63⁻0.70), respectively. After adjustment, estimates changed to 1.10 (CI 1.01⁻1.21) and 1.16 (CI 1.10⁻1.22). Unadjusted SIR for pharynx cancer among wood workers was 0.83 (CI 0.75⁻0.91), adjusted SIR was 1.14 (CI 1.03⁻1.25). For larynx cancer, results in the opposite direction were seen: unadjusted SIR for economically inactive was 1.38 (CI 1.31⁻1.46) while the adjusted SIR was 0.91 (CI 0.86⁻0.96). Conclusions: Adjustment for the latent indicators of alcohol and tobacco consumption changed risk estimates for several occupations, gave a less confounded description of risk, and may guide in the identification of true risk factors.

Investigation of GLUT1, HIF1α and TBX21 Gene Polymorphisms in Laryngeal Cancer

Objective

We aimed to investigate the association of the frequency of three single-nucleotide polymorphisms [glucose transporter isoform 1 (GLUT1) reference single-nucleotide polymorphism (rs) 710218, hypoxia-inducible factor 1 alpha (HIF1α) rs11549465, and T-box transcription factor protein 21 (TBX21) rs17250932], which have been proved to be related with various benign and malignant diseases, with the development of laryngeal cancer and its size and grade.

Methods

In this study, we included 35 patients with laryngeal cancer and 35 volunteers at least 30 years old who had smoked for at least 20 years. DNA was obtained from the blood samples of the participants using an isolation kit. Then, polymorphisms for both the groups were determined using real-time polymerase chain reaction.

Results

No significant differences were detected regarding the genotype and allele frequencies in the three polymorphisms assessed between the two groups. In the patient group, on examining the association of polymorphisms with tumor size and grade, no significant relation was observed in three polymorphisms regarding the related parameters.

Conclusion

GLUT1, HIF1α, and TBX21 polymorphisms have no impact on the development of laryngeal cancer.

Occupational exposure to petroleum-based and oxygenated solvents and hypopharyngeal and laryngeal cancer in France: the ICARE study

BACKGROUND

To examine associations between occupational exposure to petroleum-based and oxygenated solvents and the risk of hypopharyngeal and laryngeal cancer.

METHODS

ICARE is a large, frequency-matched population-based case-control study conducted in France. Lifetime occupational history, tobacco smoking and alcohol consumption were collected. Analyses were restricted to men and included 383 cases of hypopharyngeal cancer, 454 cases of laryngeal cancer, and 2780 controls. Job-exposure matrices were used to assess exposure to five petroleum-based solvents (benzene; gasoline; white spirits; diesel, fuels and kerosene; special petroleum products) and to five oxygenated solvents (alcohols; ketones and esters; ethylene glycol; diethyl ether; tetrahydrofuran). Odds ratios (ORs) adjusted for smoking, alcohol drinking and other potential confounders and 95% confidence intervals (CI) were estimated with unconditional logistic models.

RESULTS

No significant association was found between hypopharyngeal or laryngeal cancer risk and exposure to the solvents under study. Non-significantly elevated risks of hypopharyngeal cancer were found in men exposed to high cumulative levels of white spirits (OR = 1.46; 95% CI: 0.88-2.43) and tetrahydrofuran (OR = 2.63; 95CI%: 0.55-12.65), with some indication of a dose-response relationship (p for trend: 0.09 and 0.07 respectively).

CONCLUSION

This study provides weak evidence for an association between hypopharyngeal cancer and exposure to white spirits and tetrahydrofuran, and overall does not suggest a substantial role of exposure to petroleum-based or oxygenated solvents in hypopharyngeal or laryngeal cancer risk.

Comparative assessment of HPV, alcohol and tobacco etiological fractions in Algerian patients with laryngeal squamous cell carcinoma

Background

Despite the increasing incidence of laryngeal squamous cell carcinoma (LSCC) in Algeria, scarce information is available on the importance of the preventable etiological factors which may drive the disease. Remarkably, a significant number of cases occur in nonsmoker and nondrinker patients; hence, suggesting that alternative risk factors, like Human papillomavirus (HPV), might be etiologically involved. To gain more insight on the risk factors associated with the disease in the country, we evaluated the etiological fraction of HPV in comparison to tobacco and alcohol intake in LSCC patients.

Methods

To evaluate the etiopathologic fraction (EF) for HPV compared to history of tobacco and alcohol in LSCC, HPV DNA presence in 46 invasive and 3 non-invasive formalin-fixed paraffin-embedded laryngeal tumors was screened using the SPF10-DEIA-LiPA25 Assay. Demographic data and information related to exposure to the risk factors were gathered through interviewer-assisted questionnaires.

Results

We observed that 40.8% of all LSCC cases were associated with smoking, 40.8% had combined tobacco and alcohol exposure history, and 14.3% did not show prior exposure to either risk factor. 1 out of 3 in-situ carcinoma cases was positive for HPV-6. HPV prevalence was null in the invasive tumors. HPV DNA was detected in 2.38% for all studied cases. 10.2% of LSCC patients did not associate with any of the studied risk factors.

Conclusion

Here we show that HPV etiological fraction in LSCC Algerian patients is low and smoking and alcohol remain the principal etiopathologic risk for LSCC burden in Algeria.

Defining the regulatory role of programmed cell death 4 in laryngeal squamous cell carcinoma

Programmed cell death 4 (PDCD4) is decreased in many different kinds of malignant tumors. EMT endows tumor cells invasive and metastatic properties. However, few studies have determined the role of PDCD4 in the regulation of EMT in the context of laryngeal carcinoma. We examined the relationship between PDCD4 and EMT-associated proteins E-cadherin and N-cadherin using laryngeal carcinoma tissues. Gene manipulation was used to define the regulatory capacity of PDCD4. We report that PDCD4 and E-cadherin/N-cadherin expression were significantly changed in the carcinoma tissues, and their expression was associated with pathological grade, metastatic state, and clinical stage. The suppression of PDCD4 (and consequently, E-cadherin) was concomitant with increased proliferation and G2-phase arrest, decreased apoptosis, and increased cell invasion. PDCD4 upregulation reversed the above-mentioned results. In nude mice, PDCD4 knockdown increased tumor growth and pathological features, confirming the tumorigenic role of PDCD4. Finally, PDCD4 silencing was associated with dysregulation of the carcinogenic Wnt-β-catenin and the STAT3-miR-21 signaling pathways. This study revealed a dynamic regulatory relationship between PDCD4 and critical factors for EMT, establishing a broad, functional role for PDCD4 in laryngeal carcinoma, which may be propagated by the STAT3-miR-21 pathway. These findings provide new information on an EMT-associated target that may lead to a novel therapy.

Phosphorylation of gH2AX as a novel prognostic biomarker for laryngoesophageal dysfunction-free survival

Current larynx preservation treatments have achieved an improvement of laryngoesophageal dysfunction-free survival (LDS) but lead to significant toxicities and recurrences. At present, there is no evidence to select the group of patients that may benefit from preservation approaches instead of surgery. Therefore, laryngeal biomarkers could facilitate pretreatment identification of patients who could respond to chemoradiation-based therapy. In this study, we evaluated retrospectively 53 patients with larynx cancer to determine whether gH2AX phosphorylation (pH2AX) alone or in combination with the membrane protein MAP17 (PDZK1IP1) could be used as prognostic biomarkers. We also evaluated whether the completion of cisplatin treatment and radiotherapy could predict survival in combination with pH2AX.

We found that the dose of cisplatin received but not the length of the radiotherapy influenced LDS. High-pH2AX expression was associated with prolonged LDS (HR 0.26, p = 0.02) while MAP17 correlated with overall survival (OS) (HR 0.98, p = 0.05). High-MAP17 and high-pH2AX combined analysis showed improved LDS (with 61.35 months vs 32.2 months, p = 0.05) and OS (with 66.6 months vs 39.8 months, p = 0.01). Furthermore, the subgroup of high-pH2AX and optimal dose of cisplatin was also associated with OS (72 months vs 38.6 months, p = 0.03) and LDS (66.9 months vs 27 months, p = 0.017). These findings suggest that pH2AX alone or better in combination with MAP17 may become a novel and valuable prognostic biomarker for patients with laryngeal carcinoma treated with preservation approaches.

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

BACKGROUND

Few epidemiological studies have investigated the link between occupational exposure to solvents and head and neck cancer risk, and available findings are sparse and inconsistent. The objective of this study was to examine the association between occupational exposure to chlorinated solvents and head and neck cancer risk.

METHODS

We analyzed data from 4637 men (1857 cases and 2780 controls) included in a population-based case-control study, ICARE (France). Occupational exposure to five chlorinated solvents (perchloroethylene [PCE], trichloroethylene [TCE], methylene chloride [MC], chloroform [CF], and carbon tetrachloride [CT]) was assessed through job-exposure matrices. Odds ratios (ORs) and confidence intervals (95% CI) were estimated by unconditional logistic regression, adjusted for age, tobacco smoking, alcohol consumption, asbestos exposure, and other potential confounders.

RESULTS

We observed no association between chlorinated solvent exposure and head and neck cancer risk, despite a non-significant increase in risk among subjects who had the highest cumulative level of exposure to PCE, (OR = 1.81; 95% CI = 0.68 to 4.82). In subsite analysis, the risk of laryngeal cancer increased with cumulative exposure to PCE (p for trend = 0.04). The OR was 3.86 (95% CI = 1.30 to 11.48) for those exposed to the highest levels of PCE. A non-significant elevated risk of hypopharyngeal cancer was also observed in subjects exposed to the highest levels of MC (OR = 2.36; 95% CI = 0.98 to 5.85).

CONCLUSION

Our findings provide evidence that high exposure to PCE increases the risk of laryngeal cancer, and suggest an association between exposure to MC and hypopharyngeal cancer. Exposure to other chlorinated solvents was not associated with the risk of head and neck cancer.

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.

Up-Regulation of Angiotensin-Converting Enzyme (ACE) Enhances Cell Proliferation and Predicts Poor Prognosis in Laryngeal Cancer

Background

The angiotensin-converting enzyme (ACE, CD143) gene plays a crucial role in the pathology of many cancers. Previous studies mostly focused on the gene polymorphism, but the other functions of ACE have rarely been reported. The purpose of this study was to investigate the expression of ACE and its biological function, as well as its prognostic value, in laryngeal cancer.

Material/Methods

The expression of ACE was detected by quantitative real-time polymerase chain reaction (qRT-PCR) analysis in 106 patients with laryngeal cancer and 85 healthy people. Then the cell proliferation was estimated after the cell lines Hep-2 were transfected with pGL3-ACE and empty vector, respectively. In addition, the relationship between ACE expression and clinicopathologic characteristics was analyzed. Finally, Kaplan-Meier analysis was used to evaluate the overall survival of patients with different ACE expression, while Cox regression analysis was conducted to reveal the prognostic value of ACE in laryngeal cancer.

Results

Our results demonstrate that ACE is over-expressed in laryngeal cancer and thus promotes cell proliferation. The up-regulation of ACE was significantly influenced by tumor stage and lymph node metastasis. Patients with high ACE expression had a shorter overall survival compared with those with low ACE expression according to Kaplan-Meier analysis. The ACE gene was also found to be an important factor in the prognosis of laryngeal cancer.

Conclusions

Our study shows that the ACE gene was up-regulated, which promoted the cell proliferation, and it could be an independent prognostic marker in laryngeal cancer.

Genotoxic effects of cadmium in human head and neck cell line SQ20B

As cadmium may be involved in the etiology of head and neck cancers, we investigated in the present work, the cytotoxic and genotoxic effects of Cd on human larynx cells. SQ20B cells were exposed to 25 and 50 μM Cd for 48 and 72 h. Results showed a dose-dependent decrease in cell viability, especially after 48 h, associated with mitochondria alterations as showed by transmission electronic microscopy. Surprisingly, the flow cytometry shows that the cells treated with Cd have a normal proliferative cycle like the untreated cell especially in G1 or G2 phase of cell cycle. DNA damages were investigated by comet assay and immunofluorescence for gamma layer of the H2AX (g-H2AX) foci formation. Results show a strong induction of DNA double-strand breaks after Cd exposure. Overall, our results demonstrate the cytotoxicity and genotoxicity of Cd in human larynx cells and support the view that Cd could be an etiologic factor of head and neck cancers.

Expression of Th1- Th2- and Th17-associated cytokines in laryngeal carcinoma

T-helper (Th) 0 cell differentiation into Th1 or Th2 cells is dependent on a number of transcription factors that act at specific time points to regulate gene expression. Th17 cells, a subset of interleukin (IL)-17-producing T cells distinct from Th1 or Th2 cells, are considered to exhibit a critical function in inflammation and autoimmune diseases, as well as cancer development. In the present study, the expression of Th1-, Th2- and Th17-associated cytokines in laryngeal cancer and pericarcinoma tissues obtained from 57 laryngeal carcinoma patients was investigated. The association between Th1, Th2 and Th17 infiltration and tumor development was also evaluated. Reverse transcription-polymerase chain reaction and western blotting results revealed that the mRNA and protein expression of Th2 cytokines was lower, while the expression of Th1 and Th17 cytokines was higher in tumor tissues than in pericarcinoma tissues. Furthermore, the early stage cancer patients exhibited a higher level of interferon-γ, IL-2 and IL-17 mRNA expression than those at advanced stages. Cancer tissues exhibited higher Th17 cytokine expression than pericarcinoma tissues. By contrast, Th1 cytokine expression was increased in pericarcinoma tissues compared with cancer tissues. These results indicate that high expression of Th1- and Th17-associated cytokines in laryngeal carcinoma may contribute to suppression of cancer development and a relatively good prognosis.

A genetic view of laryngeal cancer heterogeneity

During the recent decades significant improvements in the understanding of laryngeal molecular biology allowed a better characterization of the tumor. However, despite increased molecular knowledge and clinical efforts, survival of patients with laryngeal cancer remains the same as 30 years ago. Although this result may not make major conclusions as preservation approaches were not broadly used until the time of database collection, it seems to be clear that there is still window for improvement. Although the cornerstone for laryngeal cancer eradication is to implement smoking cessation programs, survival progresses will be hopefully seen in the future. Introducing molecular biomarkers as predictive factors to determine which patients will benefit of preservation treatments may become one of the next steps to improve survival. Furthermore, the development of new therapeutic modalities joint to biomarkers to selectively apply such new therapy in these patients may help to define new modalities with improved survival. New inhibitors against Notch pathway, EGFR, VRK1 or DNA damage repair may become gold standard if we are able to identify patients that may benefit from them, either on survival or functional larynx preservation. It is the moment for an inflexion point on the way laryngeal cancer is clinically managed.

The clinical diagnostic value of target biopsy using narrow-band imaging endoscopy and accurate laryngeal carcinoma pathologic specimen acquisition

OBJECTIVE

To estimate the clinical significance of target biopsy for clinical diagnosis and determine accurate laryngeal lesion pathologic specimen acquisition via narrow-band imaging (NBI) endoscopy.

METHODS

A total of 138 samples from patients with laryngeal lesions (carcinoma, 118; hyperplasia, 3; mild dysplasia, 2; moderate dysplasia, 5; severe dysplasia, 5; vocal cord polyp, 1; and inflammatory lesion, 4) were collected from the Department of Otolaryngology Head and Neck Surgery of Tianjin Union Medical Center from 1 January 2013 to 1 February 2015. All patients were divided into the regular biopsy and NBI target biopsy groups; the imaging data were recorded and patient samples were biopsied. Pathologic diagnoses were used to evaluate the accuracies of regular and target biopsy.

RESULTS

Based on the pathologic diagnosis, NBI target pathology yielded an accurate laryngeal lesion pathologic specimen acquisition rate of 95.6% (65/68), significantly higher than that yielded by regular biopsy (75.7%, 53/70; χ² = 10.99, P = 0.001). In the NBI target pathology group, the correct accurate pathologic specimen acquisition rates at laryngeal cancer diagnostic stages 0 (Tis), I and II were 100%, 100% and 85.71%, respectively, which were higher than the corresponding rates in the regular biopsy group (0%, χ² = 10.000, P = 0.002; 25%, χ² = 5.625, P = 0.018; and 38.46%, χ² = 6.454, P = 0.011, respectively).

CONCLUSIONS

In cases of laryngeal carcinoma, NBI endoscopy plays an important role in clinical diagnosis and accurate pathologic specimen acquisition and could be a regular clinical method for laryngeal lesion detection.

MAP17 (PDZKIP1) as a novel prognostic biomarker for laryngeal cancer

Larynx cancer organ preservation treatments with chemo and radiotherapy have substantially improved laryngoesophageal dysfunction-free survival. However, both of them lead to a high incidence of acute and chronic toxicities and a significant number of patients relapse. To date, there is no evidence available to establish the group of patients that may benefit from preservation approaches and clinical criteria such as primary tumor extension or pretreatment tracheotomy are not validated. MAP17 is a small non-glycosylated membrane protein overexpressed in carcinomas. The tumoral behavior induced by MAP17 is associated with reactive oxygen species production in which SGLT1 seems involved. In this study we found that the levels of MAP17 were related to clinical findings and survival in a cohort of 58 patients with larynx cancer. MAP17 expression is associated with overall survival (p<0.001) and laryngoesophageal dysfunction-free survival (p=0.002). Locoregional control in patients with high MAP17 showed better outcomes than those with low MAP17 (p=0.016). Besides, a positive correlation was observed between MAP17 expression and SGLT (p=0.022) and the combination of high levels of MAP17/SGLT also led to an increased overall survival (p=0,028). These findings suggest that MAP17, alone or in combination with SGLT1, may become a novel predictive biomarker for laryngeal carcinoma.

The joint effect of asbestos exposure, tobacco smoking and alcohol drinking on laryngeal cancer risk: evidence from the French population-based case-control study, ICARE

OBJECTIVE

The objective of the study was to investigate the joint effect of occupational exposure to asbestos, and tobacco and alcohol consumption, on the risk of laryngeal cancer among men.

METHODS

We used data from a large population-based case-control study conducted in France. We estimated two-way and three-way interactions between asbestos exposure (never vs ever exposed), tobacco consumption (<20 vs. ≥20 pack-years) and alcohol consumption (<5 vs. ≥5 drinks per day). The interaction on an additive scale was assessed by estimating the relative excess risk due to interaction (RERI) and the attributable proportion due to interaction, and the interaction on a multiplicative scale was assessed by estimating the multiplicative interaction parameter (ψ). Multiplicative interactions were also assessed using fractional polynomials for alcohol drinking, tobacco smoking and asbestos exposure.

RESULTS

When compared with light-to-moderate smokers and drinkers never exposed to asbestos, the increase in laryngeal cancer risk was smallest among light-to-moderate drinkers and smokers exposed to asbestos (OR=2.23 (1.08 to 4.60)), and highest among heavy smokers and drinkers ever exposed to asbestos (OR=69.39 (35.54 to 135.5)). We found an additive joint effect between asbestos exposure and alcohol consumption (RERI=4.75 (-4.29 to 11.12)), whereas we observed a more than additive joint effect between asbestos exposure and tobacco consumption (RERI=8.50 (0.71 to 23.81)), as well as between asbestos exposure, and tobacco and alcohol consumption (RERI=26.57 (11.52 to 67.88)). However, our results did not suggest any interaction on a multiplicative scale.

CONCLUSIONS

Our results suggest that asbestos exposure, in combination with tobacco and alcohol exposure, accounted for a substantial number of laryngeal cancer cases. Our findings therefore highlight the need for prevention in activities, such as construction work, where exposure to asbestos-containing materials remains.

Gene expression analysis of laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) is one of the most common malignancies of the head and neck tumors Zhang et al., 2013 [1]). Previous studies have associated its occurrence with social activities, such as tobacco and alcohol consumption (Hashibe et al., 2007a [2]; Hashibe et al., 2007b [3]; Shangina et al., 2006 [4]). Here, we performed a genome-wide gene expression profiling in thirty-one patients positively diagnosed for LSCC, in order to investigate new targets involved in tumorigenesis.

MiR-221 as a pre- and postoperative plasma biomarker for larynx cancer patients

OBJECTIVE

In order to identify a plasma microRNA (miRNA) signature of larynx cancer (LCa), we examined miRNAs profile of plasma samples obtained from 30 LCa patients (preoperative and postoperative serum samples) and 30 healthy controls.

STUDY DESIGN

Basic science research study.

METHODS

MicroRNA profiling of eight plasma samples (four from preoperative, four from control individuals) were performed using miRNA microarray. Two of the significantly deregulated miRNAs were selected for further confirmation in the remaining samples using quantitative reverse-transcription polymerase chain reaction (qRT-PCR).

RESULTS

Microarray profiling and qRT-PCR analysis showed that miR-221 was upregulated in LCa plasma samples. Further qRT-PCR analysis demonstrated that miR-221 was at normal levels in postoperative plasma samples.

CONCLUSIONS

Plasma miR-221 may have a potential as a novel diagnostic/prognostic marker and might be considered as a therapeutic target in LCa.

LEVEL OF EVIDENCE

N/A.

Association of history of allergies and influenza-like infections with laryngeal cancer in a case-control study

Prior studies suggest that history of allergy and infections early in life might be inversely associated with cancer. We explored the association between allergies, recent influenza infections and laryngeal cancer risk. We used data from a case-control study which included 229 cases of laryngeal cancer and 769 population controls matched for age and sex. History of a physician-diagnosed allergy, influenza-like infections in the past 5 years, smoking, alcohol consumption and occupational exposure to carcinogens were self-reported. Allergies were classified into two groups (Type I and Type IV), according to the underlying immunologic mechanism. Conditional logistic regression models were fitted using laryngeal cancer as the outcome, adjusting for smoking, alcohol consumption and occupational exposure and stratified for age and sex. Having any allergy was not associated significantly with laryngeal cancer. Although Type I and Type IV allergies were non-significantly associated with laryngeal cancer, Type IV allergies showed a strong inverse association after adjusting for smoking and alcohol (OR 0.50, 95 % CI 0.22-1.2). Participants who reported at least one influenza-like infection during the past 5 years were significantly less likely to have laryngeal cancer (OR 0.57, 95 % CI 0.39-0.81). After considering fever (≥38.5 °C) as a criterion for influenza infection, the association between influenza infection and laryngeal cancer was even stronger (OR 0.29, 95 % CI 0.13-0.63). We found no significant association between any allergy and laryngeal cancer, some indication of an inverse association between Type IV allergy and laryngeal cancer, whereas recent influenza infections were inversely associated with laryngeal cancer risk.

Occupation and head and neck cancer in women-Results of the ICARE study

BACKGROUND

Few occupational studies have addressed head and neck cancer, and these studies have been predominantly conducted in men. Accordingly, our objective was to investigate the association between head and neck cancer and occupation in women.

METHODS

ICARE, a French population-based case-control study, included 296 squamous cell carcinomas of the head and neck in women and 775 controls. Lifelong occupational history was collected. Odds ratios (ORs) and 95% confidence intervals (CI), adjusted for smoking, alcohol drinking and education level, were estimated for occupations and industries.

RESULTS

An elevated OR was observed for working proprietors working for 10 years or more (OR = 3.83, 95% CI: 1.12-13.0) with a significant trend with duration of employment (P = 0.047). Elevated but non-significant ORs were observed for street vendors (OR = 3.76, 95% CI: 0.99-14.3, P for trend = 0.13), bakers (OR = 4.19, 95% CI: 0.63-27.9, P for trend = 0.06), and welders and flame cutters (OR = 2.18, 95% CI: 0.33-14.4, P for trend = 0.05).

CONCLUSIONS

This exploratory study suggests a role of occupational exposures in the development of HN cancer in women. Further investigations of exposures to specific agents are needed.

A review and meta-analysis of cancer risks in relation to Portland cement exposure

Workers engaged in the production of Portland cement may come into contact with potential occupational hazards, but existing epidemiological studies show wide variation in risk estimates for cancer incidence and mortality in relation to cement exposure. This report identified studies of cement workers and associations with cancer incidence and mortality in a systematic review and meta-analysis. A systematic review according to the PRISMA guidelines was conducted to identify studies of Portland cement workers and cancer outcomes. Meta-analyses were performed using random effects models for all cancers combined and for each cancer site with three or more reported measures of risk. A total of 26 studies were included in the review (14 occupational cohort studies and 12 case-control studies). Overall, the meta-relative risks did not provide convincing evidence for increased risks of any cancers in relation to cement exposure. Meta-SMR and 95% CIs were 0.94 (0.76 to 1.16) for six studies reporting all cancers combined, 0.93 (0.62 to 1.39) for seven studies reporting on lung cancer, 1.07 (0.72 to 1.59) for five studies reporting on stomach cancer, and 1.05 (0.79 to 1.40) for four studies reporting on colorectal cancer. Meta-relative risks for cancer incidence were similarly null for all sites with the exception of colorectal cancer which had a borderline statistically significant elevated risk (SIR=1.38, 95% CI 1.02 to 1.88). Overall, the meta-relative risks calculated across 26 published studies do not provide evidence of increased risks for cancer in relation to cement exposure.

Laryngeal cancer in Kazakhstan - ethnic, age and gender differences over time

The purpose of the present study was to provide an assessment of the incidence of cancer of the larynx in Kazakhstan with especial attention to ethnicity and gender, as well as age. The retrospective design covered all new cases of laryngeal cancer in 11 years (1999-2009). The total number was 4,967 cases, 4,535 (91.3%) in males and 432 (8.7%) in women, with a gender ratio of 10.5:1. Patients of Kazakh (31.2%) and Russian (51.4%) ethnicity accounted for the vast majority (82.6%), with Russians predominating in both sexes, but particularly in females. Age peak in Kazakhs was 70 years and older (14.6 ± 0.70/0000), and in Russians was 60-69 years (21.6 ± 1.30/0000). In the dynamics, the rates had the tendency to decrease more markedly in Russian than Kazakh men, especially in the younger groups, while increase was noted in the youngest females of both ethnicities, but again greater in Russians, presumably reflecting change in underlying lifestyle factors.

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.

Micro-ribonucleic acid expression profiling and bioinformatic target gene analyses in laryngeal carcinoma

Abnormal expression of micro-ribonucleic acid (miRNA) might be clinically valuable as a biomarker or treatment target in the early diagnosis, treatment, and prognosis of tumors. However, little is known concerning abnormal miRNA expression of laryngeal carcinoma, one of the most commonly encountered head and neck tumors. Microarray analysis was used to obtain miRNA-expression profiles of ten pairs of freshly frozen laryngeal carcinoma tissue and surrounding normal tissue specimens. Characteristic miRNAs that were significantly related to laryngeal carcinoma were identified. Verification was performed using an additional 32 pairs of samples. The expression of two miRNAs (miR-21-3p and miR-106b-3p) was upregulated in both microarray and quantitative real-time polymerase chain-reaction analyses, whereas the expression of six miRNAs (let-7f-5p, miR-10a-5p, miR-125a-5p, miR-144-3p, miR-195-5p, and miR-203) was downregulated. The decreased expression of let-7f-5p and miR-195-5p is a novel finding in head and neck cancer. The target genes of these miRNAs were also predicted through multiple software programs. The differential expression of miRNAs might be related to the early onset and development of laryngeal carcinoma, and may be exploited as new biomarkers and therapeutic targets in the treatment of laryngeal carcinoma.

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).

Occupation and educational inequalities in laryngeal cancer: the use of a job index

BACKGROUND

Previous studies tried to assess the association between socioeconomic status and laryngeal cancer. Alcohol and tobacco consumption explain already a large part of the social inequalities. Occupational exposures might explain a part of the remaining but the components and pathways of the socioeconomic contribution have yet to be fully disentangled. The aim of this study was to evaluate the role of occupation using different occupational indices, differentiating between physical, psycho-social and toxic exposures and trying to summarize the occupational burden into one variable.

METHODS

A population-based case-control study conducted in Germany in 1998-2000 included 208 male cases and 702 controls. Information on occupational history, smoking, alcohol consumption and education was collected with face-to-face interviews. A recently developed job-classification index was used to account for the occupational burden. A sub-index focussed on jobs involving potentially carcinogenic agents (CAI) for the upper aero digestive tract.

RESULTS

When adjusted for smoking and alcohol consumption, higher odds ratios (ORs) were found for lower education. This OR decreased after further adjustment using the physical and psycho-social job indices (OR = 3.2, 95%-CI: 1.5-6.8), similar to the OR using the sub-index CAI (OR = 3.0, 95%-CI: 1.4-6.5).

CONCLUSIONS

The use of an easily applicable control variable, simply constructed on standard occupational job classifications, provides the possibility to differentiate between educational and occupational contributions. Such an index might indirectly reflect the effect of carcinogenic agents, which are not collected in many studies.

Occupational dust exposure and head and neck squamous cell carcinoma risk in a population-based case-control study conducted in the greater Boston area

Head and neck cancers account for an estimated 549,000 global cancer diagnoses each year. While tobacco use, alcohol consumption, and HPV16 infection are considered to be the major risk factors for this disease, occupational risk factors, including exposure to asbestos, have also been described, although dust exposures other than asbestos have been historically understudied. We have investigated the relationship between occupational exposures to five types of dusts, including sawdust, concrete dust, leather dust, metal dust, and chimney soot, and head and neck squamous cell carcinomas (HNSCC) in the greater Boston area. We report findings from a population-based case–control study involving 951 incident HNSCC cases and 1193 controls, frequency matched on age (±3 years), sex, and town/neighborhood of residence. Multivariable logistic regression was used to assess the association between occupational exposure to each type of dust and HNSCC, overall and by primary tumor site. After adjusting for age, sex, race, smoking, alcohol consumption, education, and HPV16 serology, laryngeal carcinoma risk increased for each decade of occupational exposure to sawdust (OR = 1.2, 95% CI: 1.0, 1.3) and metal dust (OR = 1.2, 95% CI: 1.0, 1.4); and HNSCC risk increased for each decade of occupational leather dust exposure (OR = 1.5, 95% CI: 1.2, 1.9). We have provided evidence for an association between occupational sawdust and metal dust and laryngeal squamous cell carcinoma, and leather dust and HNSCC, with increasing risk with longer duration at the exposed occupation.

Mortality from solid tumors among workers in formaldehyde industries: an update of the NCI cohort

BACKGROUND

Formaldehyde, a widely used chemical, is considered a human carcinogen.

METHODS

We extended follow-up of the largest industrial cohort of workers in formaldehyde industries (n = 25,619) by 10 years through 2004. Standardized mortality ratios (SMRs) and rate ratios (RRs) were calculated for deaths from solid tumors using quantitative formaldehyde exposure estimates.

RESULTS

During 998,239 person-years, 13,951 deaths occurred. With one additional death, previously observed excesses for nasopharyngeal cancer (n = 10) persisted for peak, average intensity and cumulative exposure; RRs in the highest exposure categories were 7.66 (95% CI: 0.94, 62.34), P-trend = 0.005, 11.54 (95% CI: 1.38, 96.81), P-trend = 0.09, and 2.94 (95% CI: 0.65, 13.28), P-trend = 0.06, respectively. For all cancer, solid tumors and lung cancer, SMRs among exposed workers were elevated, but internal analyses revealed no positive associations with formaldehyde exposure.

CONCLUSIONS

Consistent with previous analyses of this cohort, this update continues to suggest a link between formaldehyde exposure and nasopharyngeal cancer.

Epidemiological evaluation of laryngeal cancer incidence in Kazakhstan for the years 1999-2009

The purpose was to provide a descriptive epidemiological assessment of the incidence of cancer of the larynx in Kazakhstan and spatial evaluation with gender characteristics. This retrospective study covered all new cases of laryngeal cancer in 11 years (1999-2009). The total number was 4,967 cases, 4,535 (91.3%) in males and 432 (8.7%) in women, with a ratio of 10.5:1. The higher incidence in men compared to women was evident in all age groups, the differences being statistically significant (p<0.05). At the same time revealed a unimodal growth with age, peaking at 70 years and older both sexes. In the dynamics, incidence rates of laryngeal cancer demonstrated a tendency to decrease, in women (T=-6.7%) this being more pronounced than in men (T=-3.3%). Levels were determined to produce cartograms of cancer of the larynx for male and female populations, clear geographical variation being evidenced. The data are discussed with reference to possible risk factors.

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.

Retrospective analysis of prognostic factors in 205 patients with laryngeal squamous cell carcinoma who underwent surgical treatment

Objectives

To investigate the most important factors affecting the prognosis of the patients with squamous cell carcinoma (SCC) of the larynx.

Methods

Based on the clinical and follow-up data, 205 patients with SCC of the larynx receiving total laryngectomy, partial laryngectomy, or CO₂ laser surgery in GuangDong General Hospital were retrospectively analyzed. A survival analysis was performed by the Kaplan-Meier method and a multivariable analysis of prognostic factors was carried out using the Cox proportional hazard model.

Results

Subtypes of carcinoma included 69.8% glottic and 30.2% supraglottic. Most patients were in N0 stage (77.6%), and 22.4% patients were in N1∼N3 stage. Over half of the patients were in T1∼T2 stage (55.1%), 20.0% in T3, and 24.9% in T4. Mean follow-up duration was 49.2 months. The survival rates 1, 2, and 3 years after the surgery were 99.0%, 91.7%, and 81.5%, respectively. The survival rate for those patients with clinical stage IV was significantly lower than for those with clinical stage I and II (p<0.001 and p = 0.013, respectively). The disease-free progression rates 1, 2, and 3 years after the surgery were 83.9%, 74.6%, and 71.2%, respectively. Futhermore, those patients with a Charlson score of 1 to 2 and ≥3 had higher risk of mortality than those with a Charlson score of 0 (hazard ratios of 1.8 and 2.41 p = 0.042 and p = 0.008). Multivariable analysis revealed that clinical stage, surgical margin, and comorbidity were significantly associated with both mortality and disease-free progression.

Conclusion

The surgical resection margin, clinical stage, and comorbidity were independent factors affecting the laryngeal cancer prognosis. The survival rates were lower for patients with advanced laryngeal cancer, positive surgical margins, or severe comorbidity, suggesting the importance of early diagnosis, early treatment, negative surgical margins, and conditions of comorbidity.

Influence of liquid and gas flow rates on sulfuric acid mist removal from air by packed bed tower

The possible emission of sulfuric acid mists from a laboratory scale, counter-current packed bed tower operated with a caustic scrubbing solution was studied. Acid mists were applied through a local exhaust hood. The emissions from the packed bed tower were monitored in three different categories of gas flow rate as well as three liquid flow rates, while other influencing parameters were kept almost constant. Air sampling and sulfuric acid measurement were carried out iso-kinetically using USEPA method 8. The acid mists were measured by the barium-thorin titration method. According to the results when the gas flow rate increased from 10 L/s to 30 L/s, the average removal efficiency increased significantly (p < 0.001) from 76.8 ± 1.8% to 85.7 ± 1.2%. Analysis of covariance method followed by Tukey post-hoc test of 92 tests did not show a significant change in removal efficiency between liquid flow rates of 1.5, 2.5 and 3.5 L/min (p = 0.811). On the other hand, with fixed pressure loss across the tower, by increasing the liquid/gas (L/G) mass ratio, the average removal efficiency decreased significantly (p = 0.001) from 89.9% at L/G of <2 to 83.1% at L/G of 2–3 and further to 80.2% at L/G of >3, respectively. L/G of 2–3 was recommended for designing purposes of a packed tower for sulfuric acid mists and vapors removal from contaminated air stream.

Laryngeal cancer and silica dust exposure: a systematic review and meta-analysis

BACKGROUND

Individual epidemiological studies generally lack the power to examine the association between silica exposure or silicosis and laryngeal cancer. We summarized pertinent evidence from published literature by using meta-analysis.

METHODS

A systematic literature search was performed to identify cohort and case-control studies, and the method of meta-analysis was used to combine standardized mortality ratios (SMRs) or standardized incidence ratios (SIRs) from cohort studies and odds ratios (ORs) from case-control studies.

RESULTS

A significantly increased risk of laryngeal cancer (pooled OR = 1.39, 95% confidence interval (95% CI): 1.17-1.67) among workers exposed to silica dust was observed by combining six case-control studies with adjustment for smoking and alcohol consumption. A similarly increased but statistically non-significant risk estimate was observed from cohort studies, with a pooled SMR of 1.38 (95% CI: 0.79-1.96) for silicosis cases; and a pooled SMR of 1.13 (95% CI: 0.82-1.45) and a pooled SIR of 1.50 (95% CI: 0.59-2.42) for workers with silica dust exposure.

CONCLUSION

This systematic review demonstrated a weak association between silica or silicosis and laryngeal cancer. Owing to the inherent limitations of the original studies, interpretation of the results of this meta-analysis should be cautious.