Epidemiology of pleural mesothelioma in a population with non-occupational asbestos exposure

Our plain-English summary of Epidemiology of pleural mesothelioma in a population with non-occupational asbestos exposure, by M. Metintas, S. Metintas, G. Ak, et al (Respirology, 2008).

The study

• Authors: M. Metintas, S. Metintas, G. Ak, S. Erginel, F. Alatas, E. Kurt, I. Ucgun, H. Yildirim
• Journal: Respirology
• Published: 2008;13(1):117-21
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background And Objective: This study describes the epidemiology of malignant pleural mesothelioma (MPM) in a rural population with environmental asbestos exposure.

Methods: Patients with diagnosed MPM were recruited and their relevant demographic and exposure data were analysed.

Results: A total of 131 patients with MPM (59 men, 72 women) were studied. The patients' mean age was 57.8 years and the mean exposure duration was 28.9 years. The cumulative fibre count of the villagers ranged from 0.19 to 14.61 fibre/mL-years. Of the 131 patients, 85 had epithelial cell type, 20 had mixed, and eight had sarcomatous pleural mesothelioma. No significant relationship was found between asbestos fibre type and age, exposure period, or cellular type of MPM; similarly, no significant relationship could be found between the cellular type and age or exposure period. Patients with sarcomatous mesotheliomas were considerably older. Only five of 131 (3.8%) patients had a family history of mesothelioma.

Conclusions: Environmental exposure to asbestos begins at birth and this may be important in the age of disease onset, if a threshold model for cancer initiation is operative. Both men and women had an excess risk of mesothelioma. Given that a family history of MPM was not common in this relatively homogenous patient group, a genetic predisposition to mesothelioma appears unlikely.

In plain English

This study looked at patients with malignant pleural mesothelioma referred to a single hospital in Eskişehir, Turkey, between May 1989 and May 2006. Of 142 consecutive patients whose disease was confirmed by tissue diagnosis, 131 (92%) had been exposed to asbestos through contact with 'white soil', a local soil containing asbestos. Four had occupational exposure and seven had no known exposure. The 131 were 59 men and 72 women. Their mean age at diagnosis was 57.8 years, the youngest was 26, and their mean exposure duration was 28.9 years. Soils from their villages contained fiber mixtures including chrysotile, actinolite, tremolite, anthophyllite and antigorite. Tumours were epithelial in 85, mixed in 20 and sarcomatous in 8. The authors found no significant relationship between fiber type and age, exposure period or cell type. Patients with the mixed type were younger than those with the sarcomatous type (mean 53.2 versus 64.0 years). Five patients (3.8%) had a family history of mesothelioma. The authors concluded that both men and women had an excess risk, and that a genetic predisposition appears unlikely.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Prospective case series of consecutive patients with malignant pleural mesothelioma diagnosed at a single referral hospital, with descriptive analysis of demographic and exposure data
• Who was studied: 142 consecutive patients with histopathologically confirmed malignant pleural mesothelioma in Eskişehir, Central Anatolia, Turkey, May 1989 to May 2006. The main analysis covered the 131 with white-soil exposure: 59 men and 72 women, ages 26 to 80, living in or coming from 72 villages.
• Exposure: Non-occupational (environmental) asbestos exposure from contact with white soil, primarily contaminated with tremolite or tremolite combined with other fibers. Patients were grouped by village zone. Zone 1 had anthophyllite plus chrysotile (5 cases). Zone 2 had chrysotile, actinolite and antigorite (37 cases). Zone 3 had chrysotile, actinolite, tremolite, anthophyllite and antigorite (89 cases).
• Main results:
  • Of the 142 patients, seven had no known asbestos exposure, four had occupational exposure, and 131 (92%) had exposure through white-soil contact.
  • Among the 131 white-soil-exposed patients (59 men, 72 women), mean age at diagnosis was 57.8 years and mean exposure duration was 28.9 years.
  • The youngest patient was 26 at diagnosis. The largest age group was 60 to 69 years, at 35.1% of the 131 patients.
  • Cell types among the 131 patients: 85 epithelial, 20 mixed, 8 sarcomatous.
  • No significant relationship was found between asbestos fiber type (village zone) and age, exposure period, or cell type.
  • Patients with the mixed cell type (mean age 53.2 years, n = 20) were significantly younger than those with the sarcomatous type (mean age 64.0 years, n = 8), P less than 0.05. Mean exposure duration did not differ significantly by cell type.
  • 16 patients (12.2%) had lived in villages all their lives (constant exposure group) and 115 (87.8%) had moved to a city or stopped using white soil (partial exposure group). Mean exposure durations of the two groups were 24.7 and 58.8 years (P less than 0.001). Mean age at diagnosis was 58.8 years in the continuous group and 57.6 years in the partial group (P greater than 0.05).
  • Five of the 131 patients (3.8%) had a family history of mesothelioma. Two of these were related to each other, and three had other first-degree relatives in their villages with mesothelioma.
  • Smoking was reported in 48 of 59 men (given as 77.9%, or 78% in the discussion) and 8 of 72 women (11.1%).
  • Citing earlier measurements from the region's villages, the authors reported a lifetime cumulative fiber count for villagers of 0.19 to 14.61 fibers per mL-years.
• The authors' conclusion: The authors concluded the following:
• Environmental exposure begins at birth, which may matter for age at disease onset if a threshold model applies.
• Both men and women had an excess risk of mesothelioma.
• Because family history of mesothelioma was uncommon in this relatively homogeneous group, a genetic predisposition appears unlikely.
• Their findings suggest that cigarette smoking does not play a key role.
• Limitations the authors state:
  • The authors note that ambient air fiber measurements most likely underestimate villagers' true round-the-clock exposure, because measurements can be affected by environmental conditions.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Epidemiology, Pleural Mesothelioma, Asbestos Exposure, Mesothelioma, Environmental Exposure.

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• Tissue burden of asbestos in nonoccupationally exposed individuals from east Texas — R.F. Dodson, M.G. Williams, et al. (1999)
• Assessment of environmental asbestos exposure in Turkey by bronchoalveolar lavage — P. Dumortier, L. Coplü, et al. (1998)
• Malignant mesothelioma due to non-occupational asbestos exposure from the Italian national surveillance system (ReNaM): epidemiology and public health issues — A. Marinaccio, A. Binazzi, et al. (2015)
• Factors affecting soluble mesothelin related protein levels in an asbestos-exposed population — E.K. Park, P.S. Thomas, et al. (2010)

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