Radon exposure and oropharyngeal cancer risk

doi:10.1016/j.canlet.2015.08.025

Cancer Letters

Volume 369, Issue 1, 1 December 2015, Pages 45-49

https://doi.org/10.1016/j.canlet.2015.08.025 Get rights and content

Highlights

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Radon exposure might be linked with oral and pharyngeal cancers.
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The available literature does not show an association between radon exposure and these tumours.
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This association does not appear to exist neither for miners nor for general population.
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No study has been found analysing directly this association. Such studies are encouraged.

Abstract

Oropharyngeal cancer is a multifactorial disease. Alcohol and tobacco are the main risk factors. Radon is a human carcinogen linked to lung cancer risk, but its influence in other cancers is not well known. We aim to assess the effect of radon exposure on the risk of oral and pharyngeal cancer through a systematic review of the scientific literature. This review performs a qualitative analysis of the available studies. 13 cohort studies were included, most of them mortality studies, which analysed the relationship between occupational or residential radon exposure with oropharyngeal cancer mortality or incidence. Most of the included studies found no association between radon exposure and oral and pharyngeal cancer. This lack of effect was observed in miners studies and in general population studies. Further research is necessary to quantify if this association really exists and its magnitude, specially performing studies in general population, preferably living in areas with high radon levels.

Introduction

Oropharyngeal cancer is the eleventh most common cancer in the world [1]. Oral cancer incidence is globally growing, especially in developing countries. This is due to the increasing prevalence of some risk factors and population ageing. In Europe, incidence and mortality rates for both sexes are 11 per 100.000 and 4.7 per 100.000 for males and females, respectively [2]. In Spain, the estimated incidence and mortality rates are 8.8 per 100.000 and 2.4 per 100.000 for oral cavity cancer, and 3.3 per 100.000 and 1.6 per 100.000 for pharyngeal cancer for men and women, respectively [3].

Oral and pharyngeal cancers are multifactorial diseases. Tobacco and alcohol are the most important risk factors. Between 43 and 60% of oral cavity, pharynx or nasopharynx cancers may be due to tobacco consumption with or without alcohol consumption [4]. These two factors acting together produce a synergistic multiplicative effect that significantly increases the risk [5]. Other forms of tobacco consumption such as betel quid are also important factors that contribute to the risk especially in Asiatic regions [6].

There are also specific risk factors depending on the oral cavity region: excessive solar exposition is the most important factor for lip cancer, and Human Papillomavirus is a risk factor for pharyngeal cancer principally, and its incidence is growing [7]. Moreover, unhealthy diets without fruit and vegetable consumption, or a low sociocultural level with no access to medical assistance or no oral hygiene education, preclude a higher oropharyngeal cancer risk [8].

Radon is a noble radioactive gas. It emanates from rocks and soils and tends to concentrate in closed spaces such as houses or indoor workplaces. When radon gas is inhaled, densely ionising alpha particles emitted by deposited short-lived decay products of radon can interact with biological tissues leading to DNA damage. Cumulative exposure to decay products of radon in low concentration is related to a higher oncogenic risk. Radon was classified as a human lung carcinogen in 1988 by the IARC and nowadays there is strong evidence about its relationship with lung cancer in the general population [9]. Residential radon was recently included as an exposure to avoid in the last version of the European Code Against Cancer [10].

Although there is strong evidence of the relationship between residential radon and lung cancer, the possible association with other neoplasms is under discussion. Published studies have found an association between residential radon and leukaemia, central nervous system [11], skin cancer [12] and oesophageal cancer [13]. We could not find any study assessing exclusively the possible relationship between oral and pharyngeal cancer and radon, but it is possible to extract data from larger studies where many cancer types have been analysed. Knowing that radon can damage by inhalation, and the carcinogenicity of α particles, it might be biologically plausible that radon exposure could pose a risk for oral and pharyngeal cancers.

We aim to analyse the possible association between radon exposure and cancers of the oral cavity and pharynx through a systematic review of the scientific literature.

Section snippets

Materials and Methods

We made a systematic review of the scientific literature using MEDLINE and EMBASE databases in order to find all the articles analysing the possible relationship between radon exposure and oral or pharyngeal cancer. We used a combination of free text words and MeSH terms in order to find all the available publications. We decided to perform an exhaustive search instead of a pertinent search in order to find all the available papers on the topic at the cost of obtaining many useless works that

Results

The search resulted in the inclusion of 13 articles, all of them written in English. Eleven were studies on miners, and the other two were performed on the general population. The studies were published between 1988 and 2014, and were carried out in Europe or North America except for one study in Japan. The characteristics of the included studies are shown in Table 2.

Included studies are mostly mortality studies, where the number of observed deaths from oral or pharyngeal cancer is compared

Discussion

This is the first systematic review analysing the possible relationship between residential radon and oropharyngeal cancer. Oral and pharyngeal incidence or mortality was not significantly associated with radon exposure in most of the included studies. This lack of association occurs in miners studies and also in population-based studies. It is important to highlight that the quality of the available studies is limited and that radon exposure assessment was indirect in most cases.

Included

Conflict of interest

The authors declare that they do not have any conflict of interest.

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Cited by (14)

A systematic review on groundwater radon distribution with human health consequences and probable mitigation strategy
2022, Journal of Environmental Radioactivity
Citation Excerpt :
However, it can probably also causes melanoma, kidney cancer, haematological cancers or may be brain tumors (Bräuner et al., 2013). The relationship between radon and cancer of the extrathoracic and liver is also established but stomach and pancreas are still in doubt, while no such correlation has been confirmed for oral and throat cancer (Kelly-Reif et al., 2020; Salgado-Espinosa et al., 2015; Schubauer-Berigan et al., 2009). Researchs have been conducted to find the correlation between the drinking water radon contamination and gastrointestinal malignancies, but the consequences are contradictory (Auvinen et al., 2005).
Groundwater radon contamination is a serious global concern for its eco-toxicological effects. The major health hazard occurs due to toxic indoor air inhalation and consumption of contaminated drinking water supplied from different distribution systems, especially groundwater. There are fragmented reports on the measurement of radon contamination and their health consequences with physical radon removal strategies as well as characterization of inhabitant microbial communities. As it concerned with human health, collective information is much essential on their groundwater distribution, their physicochemical properties and possible mitigation strategies, not done so far. In such prospect, this review summarizes the physicochemical properties of radon, their sources, global as well as Indian groundwater radon contamination scenario, health effects and inhabitant microbes along with their survival strategies. It also summarizes the physical radon removal techniques and especially emphasizes the microbes based bioremediation process as well as a combination of both as a future effective radon remediation process.
Radon exposure and genitourinary cancer in miners
2021, Gaceta Sanitaria
Evaluar la asociación entre la exposición al radón y el cáncer genitourinario en población minera a través de una revisión sistemática de la literatura científica.
Se realizó una revisión sistemática de la literatura científica en MEDLINE (PubMed) combinando términos MeSH (Medical Subject Heading) y términos libres. Se realizó una escala específica de valoración de la calidad de los estudios incluidos.
Se incluyeron 17 estudios. Todos fueron estudios de cohortes, excepto uno que fue un pool de datos. Todos los estudios incluían análisis de la relación entre la exposición al radón y el cáncer genitourinario. Los resultados son ambiguos: unos estudios apuntan hacia una asociación entre la exposición y el cáncer genitourinario, especialmente de riñón, y otros no encuentran asociación.
Los estudios incluidos presentan una gran heterogeneidad metodológica. No puede concluirse que exista una asociación entre la exposición al radón y el cáncer genitourinario. Es necesaria más investigación sobre el tema, con estudios que tengan más potencia estadística y mejor control de las variables confusoras, y preferentemente que sean prospectivos.
To assess the association between exposure to radon and genitourinary cancer in a mining population through a systematic review of the scientific literature.
A systematic review of the scientific literature was carried out in MEDLINE (PubMed), combining MeSH (Medical Subject Heading) terms and free terms. We applied a specific scale to assess the quality of the included studies.
We included 17 studies; all were cohort studies with the exception of one which was a pooling of data. All studies included analysed the relationship between exposure to radon and genitourinary cancer. While some studies point towards an association between radon exposure and genitourinary cancer, especially kidney cancer, others do not find such association.
The included studies showed great heterogeneity. It cannot be concluded that there is an association between exposure to radon and genitourinary cancer. More research is needed on this topic, designing studies with higher statistical power, better control of confounders, and preferably prospective.
Reply: Residential radon and small cell lung cancer. A systematic review
2019, Cancer Letters
Detection of radon with biosensors based on the lead(II)-induced conformational change of aptamer HTG and malachite green fluorescence probe
2018, Journal of Environmental Radioactivity
Citation Excerpt :
In particular, radon can be accumulated in the fat cells of bone marrow for a long time, causing α and β radiation harm to haematopoietic stem cells(Zhang et al., 2011). Consequently, skin cancer, leukaemia, functional damage to the central nervous system, and oesophageal cancer can develop(Salgado-Espinosa et al., 2015). With the development of the nuclear industry, the probability of nuclear accidents has increased, making the public pay more attention to the detection and monitoring of radioactive substances, such as radon.
The aim of this paper is to assemble a new biosensor for detecting the accumulated radon dose in the environment to achieve rapid monitor of radon. Based on the correlation between radon and its stable decay daughter ²¹⁰Pb, a biosensor using the lead-induced specific aptamer HTG conformational changes, and the organic dye malachite green (MG) as a fluorescent probe was assembled. In these studies, we explored a novel, sensitive, label-free, fluorescence biosensing method for the detection of both radon and lead. The fluorescence intensity difference has a linear relationship with Pb²⁺ and the accumulated radon concentration from 6.87 × 10³ Bq·h/m³ to 3.49 × 10⁵ Bq·h/m³. The lead and radon detection limits of this method are 6.7 nmol/L and 2.06 × 10³ Bq·h/m³, respectively. The student's t-test results indicated that the new method was reliable and stable. The detection method is sensitive, accurate, easy to operate, has a wide linear range and is highly selective. In the sampling and determination processes of radon, the radiation harm to human health can be effectively avoided.
Exposure to Radon and Kidney Cancer: A Systematic Review and Meta-analysis of Observational Epidemiological Studies
2018, Biomedical and Environmental Sciences
To evaluate the possible association between radon exposure and kidney cancer.
We performed a systematic review and a meta-analysis based on random effect models to provide a pooled association measure.
We subjected 8 studies (overall relative risks and 95% confidence intervals: 1.01, 0.72 to 1.43, I² = 64.4%) to meta-analysis. Subgroup analysis revealed a marginally significant association between radon exposure and kidney cancer in studies conducted in Europe. Two population-based studies provided no evidence for the increased risk of kidney cancer in the general population.
The association between radon and kidney cancer remains unclear but cannot be excluded because of its biological plausibility and the limited number and quality of existing studies. Additional data from the general population and well-designed miner cohort studies are needed to reveal the real relationship between radon exposure and kidney cancer.
Alcohol consumption and lung cancer risk in never smokers
2016, Gaceta Sanitaria
Citation Excerpt :
The scale with the different criterion and its weighting appears in Table 1. We have employed similar scales in systematic reviews in residential radon and lung cancer in never smokers20 and for residential radon and oral and pharyngeal cancers.21 We obtained 832 papers through the literature search.
The main objective of this study is to analyse the role of alcohol consumption on lung cancer risk in people who have never smoked.
We conducted a systematic review of the scientific literature following the PRISMA statement. We searched Medline, EMBASE and CINAHL using different combinations of MeSH terms and free text. We included cohort studies, pooled cohort studies and case-control studies comprising at least 25 anatomopathologically-confirmed diagnoses of lung cancer cases, a sample size larger than 100 individuals and more than five years of follow-up for cohort studies. We excluded studies that did not specifically report results for never smokers. We developed a quality score to assess the quality of the included papers and we ultimately included 14 investigations with a heterogeneous design and methodology.
Results for alcohol consumption and lung cancer risk in never smokers are inconclusive; however, several studies showed a dose-response pattern for total alcohol consumption and for spirits. Heterogeneous results were found for wine and beer.
No clear effect is observed for alcohol consumption. Due to the limited evidence, no conclusion can be drawn for beer or wine consumption. There is little research available on the effect of alcohol on lung cancer risk for people who have never smoked, and more studies are urgently needed on this topic.
El objetivo principal es analizar el papel que el consumo de alcohol desempeña en el riesgo de cáncer de pulmón en personas que nunca han fumado.
Se ha realizado una revisión sistemática de la literatura científica siguiendo la Declaración PRISMA. Se realizaron búsquedas en Medline, EMBASE y CINAHL utilizando diferentes combinaciones de términos MeSH y texto libre. Incluimos estudios de cohortes, cohortes agrupadas y estudios de casos y controles que cumpliesen: mínimo de 25 casos de cáncer de pulmón confirmados por anatomía patológica, muestra total de al menos 100 individuos y más de 5 años de seguimiento en estudios de cohortes. Se excluyeron aquellos trabajos que no aportasen resultados individualizados para las personas no fumadoras. Se desarrolló una escala de calidad para valorar los trabajos incluidos. Finalmente, se incluyeron 14 investigaciones, con un diseño y una metodología heterogéneos.
Los resultados para el consumo de alcohol y el riesgo de cáncer de pulmón en personas nunca fumadoras no son concluyentes. Sin embargo, varios estudios muestran un patrón de dosis-respuesta para el consumo total y para el consumo de bebidas espirituosas. Los resultados obtenidos para vino y cerveza son heterogéneos.
No se observa un efecto claro para el consumo de alcohol. Debido a la limitada evidencia, no puede obtenerse ninguna conclusión para el consumo de cerveza y vino. Hay pocas investigaciones disponibles sobre el efecto del alcohol en el riesgo de cáncer de pulmón en personas que nunca han fumado. Se necesitan, con urgencia, más estudios sobre este tema.

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Mini-reviewRadon exposure and oropharyngeal cancer risk

Highlights

Abstract

Introduction

Section snippets

Materials and Methods

Results

Discussion

Conflict of interest

Eur. J. Cancer

J. Chronic Dis

Oral Oncol

Cancer Lett

Environ. Res

Cancer incidence and mortality worldwide: sources, methods and major patterns in GLOBOCAN 2012

Int. J. Cancer

Strengthening the prevention of oral cancer: the WHO perspective

Community Dent. Oral Epidemiol

Betel-quid and areca-nut chewing and some areca-nut derived nitrosamines

IARC Monogr. Eval. Carcinog. Risks Hum