The WorkSafeBCCHSPR Research Partnership

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The Burden of Asbestos-related Disease Paul
Demers, Chris McLeod, Tracy Kirkham, Fan Xu,
Mieke Koehoorn

• The WorkSafeBC-CHSPR Research Partnership
• University of British Columbia

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British Columbia
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Asbestos-Related Workers Compensation Claims, BC
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Recognition of Asbestos-related Disease
From U.S. IOM Asbestos, Selected Cancers,
2006. Original sources Becklake (1976), Liddell
(1997), Ross Nolan (2003)
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Mesothelioma Surveillance

• Case Identification
• Tumour Registry Records (1970-2005)
• Accepted Workers Compensation Claims (1970-2005)
• Trends and patterns examined 1970-2005

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Asbestosis Surveillance

• Case Identification
• Workers compensation data (1985-2004)
• Accepted Claims
• Hospital discharge records (1985-2004)
• any hospital visits
• Medical services data (1991-2004)
• at least 2 outpatient visits
• Trends and patterns examined 1992-2004

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Assessing the Burden for Other Asbestos-related
Cancers

• Calculate based on standard methods using
  case-control or cohort studies?
• Estimate based on a ratio to mesotheliomas in
  cohort studies?
• For other cancers, estimate based on a ratio to
  excess lung cancers in cohort studies?

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Attributable Fraction Population-Based
Case-Control Studies

• Lung Cancer ranged from 1 to 17 for asbestos
• The highest fractions were from highly
  industrialized or other areas with a high
  prevalence of exposure
• from Vineis Simonato, Arch Environ Health, 1991

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Asbestos-Related Lung Cancer in BC Ratio to
Mesothelioma

• A range of ratios have been proposed, generally
  between 1 and 4
• Using the same cohort studies as IOM a mean of
  5.7 was observed (geometric mean of 2.7)
• There are approximately 65 mesotheliomas
  diagnosed each year in BC
• If 2 asbestos-related lung cancers for each
  mesothelioma 130 lung cancers per year
  (equivalent to 5 of all lung cancers)

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US IOM 2006 Review of Other Asbestos-related
Cancers
U.S. National Academy of Sciences. Asbestos
Selected Cancer, 2006.
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Ratio-based Predictions using Studies from US
IOM 2006 Review
Ratios based geometric means. Only including
studies where an excess of lung cancer and the
cancer of interest observed.
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Summary

• In British Columbia (current population 4.2
  million), each year there are
• 60-70 new cases of mesothelioma
• 90-100 new cases of asbestosis
• In addition there may be
• 120-140 new cases of lung cancer
• 18-21 other cancers
• these numbers may be greatly underestimated

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Conclusions

• Much of the burden of asbestos-related disease
  remains unrecognized
• Mesothelioma is relatively well-ascertained
• Assessing trends in asbestosis is possible, but
  presents more challenges
• Much better data is needed to estimate the burden
  of lung cancer, the most common asbestos related
  disease
• There are likely smaller numbers of other
  cancers, but our numbers may be greatly
  underestimated
• Decades after major reductions in exposure, the
  burden is very high

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Questions?
Ad in Scientific American 1916
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Estimated Asbestos Use in Canada
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Assessing the Burden for Other Cancers

• Calculate based on standard attributable risk
  methods using case-control studies?
• Estimate based on a ratio to mesotheliomas in
  cohort studies?
• Estimate based on a ratio to excess lung cancers
  in cohort studies?