Plasma vitamin concentrations and incidence of mesothelioma and lung cancer in individuals exposed to crocidolite at Wittenoom, Western Australia

Our plain-English summary of Plasma vitamin concentrations and incidence of mesothelioma and lung cancer in individuals exposed to crocidolite at Wittenoom, Western Australia, by H.S. Alfonso, L. Fritschi, N.H. de Klerk, et al (European Journal of Cancer Prevention, 2006).

The study

• Authors: H.S. Alfonso, L. Fritschi, N.H. de Klerk, G.L. Ambrosini, J. Beilby, N. Olsen, A.W. Musk
• Journal: European Journal of Cancer Prevention
• Published: 2006;15(4):290-4
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Increased rates of death from asbestos-related diseases have been reported in former workers and residents exposed to crocidolite (blue asbestos) at Wittenoom (Western Australia). The relationships between plasma concentrations of retinol, carotene and vitamin E and incidence of mesothelioma and lung cancer in a cohort of people from this town were examined. The relationships were evaluated by survival analyses using data obtained at the first visit, at each visit and with the rate of change of each vitamin during the period of follow-up. Of 1953 study participants, 65 developed mesothelioma during the follow-up, and 47 developed lung cancer. A lower incidence of mesothelioma was related to plasma concentrations of retinol at the first visit [hazard ratio (HR)=0.63, 95% confidence interval=0.41-0.99], and to measurements at each visit (HR=0.71, 95% confidence interval=0.50-1.00). Plasma carotene concentrations at the first measurement, but not during the follow-up period, were associated with lower incidence of lung cancer in men and in workers. No significant associations were found between carotene concentrations and incidence of mesothelioma. Vitamin E concentrations were not significantly associated with mesothelioma or lung cancer incidence. These findings suggest that people with chronically low plasma levels of retinol have increased risk of developing mesothelioma and lung cancer.

In plain English

The authors followed 1953 former workers and residents of Wittenoom, Western Australia, exposed to crocidolite (blue asbestos), who had joined a vitamin A supplementation programme begun in 1990. They tested whether plasma levels of retinol, carotene and vitamin E were linked to mesothelioma or lung cancer diagnosed up to 31 July 2002. Analyses allowed for age, sex, asbestos exposure, smoking and liver tests. During follow-up, 65 participants developed mesothelioma (51 pleural, 14 peritoneal) and 47 developed lung cancer. Each additional unit of plasma retinol (printed as mmol/l) was linked to lower mesothelioma risk at the first measurement (hazard ratio 0.63, 95% confidence interval 0.41–0.99) and at each visit (0.71, 0.51–1.00). No significant link between retinol and lung cancer was found. Higher carotene at the first measurement was linked to fewer lung cancers only when the analysis was limited to men or to workers. Vitamin E showed no significant links. The authors concluded that retinol was inversely associated with mesothelioma but not with lung cancer. They noted the observational design could not separate vitamin levels from other programme components.

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: Observational cohort analysis (Cox regression survival analysis) of participants in a vitamin A supplementation programme
• Who was studied: 1953 former workers and residents of Wittenoom, Western Australia, enrolled in the Vitamin A Programme (accepting participants from July 1990). They were followed from their first plasma vitamin measurement until cancer diagnosis or 31 July 2002.
• Exposure: Past exposure to crocidolite at Wittenoom, estimated as cumulative exposure from historical measurements and employment or residence records. The main factor studied was plasma levels of retinol, carotene and vitamin E in people given retinol or beta-carotene supplements.
• Main results:
  • Of 1953 participants, 65 developed mesothelioma (51 pleural and 14 peritoneal) and 47 developed lung cancer.
  • Retinol at the first measurement was inversely related to later mesothelioma: hazard ratio 0.63 (95% CI 0.41–0.99) per one-unit increase (units printed as mmol/l), which the authors describe as a 37% reduction in risk. For lung cancer the hazard ratio was 0.90 (0.54–1.51), not statistically significant.
  • Retinol measured at each visit was inversely associated with mesothelioma: hazard ratio 0.71 (95% CI 0.51–1.00) per one-unit increase (units printed as mmol/l), P = 0.05, described as a 29% reduction. No significant association was found with lung cancer: hazard ratio 0.76 (0.50–1.17).
  • In the whole cohort, carotene at the first measurement tended to be inversely related to lung cancer (hazard ratio 0.41, 95% CI 0.15–1.14, P = 0.08). Carotene was not significantly related to mesothelioma.
  • In analyses restricted to males and to workers, carotene at the first measurement was associated with lower lung cancer incidence. For males the hazard ratio was 0.24 (95% CI 0.06–0.88, P = 0.03); for workers it was 0.23 (95% CI 0.06–0.85, P = 0.02).
  • Vitamin E concentrations were not significantly associated with mesothelioma or lung cancer.
  • Rates of change over time of retinol, carotene and vitamin E were not statistically associated with either cancer.
• The authors' conclusion: The authors concluded that plasma retinol was inversely associated with mesothelioma incidence but not with lung cancer. They found these relationships were not affected by asbestos exposure or smoking status. They suggested the link may reflect an indirect effect, such as a presymptomatic stage of cancer at entry, rather than a direct effect of retinol.
• Limitations the authors state:
  • Because the analysis was observational, the effects of vitamin levels could not be separated from other parts of the programme, such as dietary and smoking advice or psychological effects of taking part.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Wittenoom, Western Australia

All asbestos mines

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Lung Cancer, Crocidolite, Wittenoom, Hazard Ratio, confidence interval.

Related studies

• Plasma retinol, carotene and vitamin E concentrations and lung function in a crocidolite-exposed cohort from Wittenoom, Western Australia: a cohort study — H.S. Alfonso, L. Fritschi, et al. (2005)
• Retinol supplementation and mesothelioma incidence in workers earlier exposed to blue asbestos (Crocidolite) at Wittenoom, Western Australia — H.S. Alfonso, A. Reid, et al. (2010)
• Vitamin A and cancer prevention I: observations in workers previously exposed to asbestos at Wittenoom, Western Australia — A.W. Musk, N.H. de Klerk, et al. (1998)
• Malignant pleural and peritoneal mesotheliomas in former miners and millers of crocidolite at Wittenoom, Western Australia — G. Berry, N.H. de Klerk, et al. (2004)
• Cancer incidence among women and girls environmentally and occupationally exposed to blue asbestos at Wittenoom, Western Australia — A. Reid, J. Heyworth, et al. (2008)
• Malignant mesotheliomas in former miners and millers of crocidolite at Wittenoom (Western Australia) after more than 50 years follow-up — G. Berry, A. Reid, et al. (2012)

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