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Mesothelioma cases in Ontario continue to rise (Nov. 2015)

Between 1981 and 2012, the number of newly diagnosed cases of mesothelioma among Ontario men rose steadily at an average of 5.5 per cent per year, from about 30 cases in 1981 to about 180 in 2012. Incidence rates rose from 0.81 per 100,000 to 2.23 per 100,000 over the same period. Ontario’s incidence rate for mesothelioma was lower than the national average over the 1981–2012 period, but because Ontario’s population is large, the number of cases diagnosed each year was high in comparison to most other provinces.1

'Figure: New cases of Mesothelioma in Ontario men, 1981–2012'

Figure description:

This figure is a line chart titled 'New cases of mesothelioma in Ontario men, 1981–2012'.

The horizontal axis is labeled 'Year of diagnosis' and lists the years 1981 to 2012 in increments of 5 years.

The vertical axis is labeled 'New cases of mesothelioma (3-year moving average)' and increase from 0 to 200 in increments of 20.

New cases of mesothelioma,* in Ontario men, 1981–2012
Year of diagnosis Cases
1982 35
1983 37
1984 43
1985 45
1986 48
1987 50
1988 55
1989 57
1990 57
1991 58
1992 60
1993 67
1994 68
1995 82
1996 90
1997 98
1998 93
1999 90
2000 93
2001 104
2002 115
2003 125
2004 128
2005 138
2006 139
2007 148
2008 141
2009 150
2010 166
2011 182
Source: Ontario Cancer Registry, 2015 (Cancer Care Ontario)
*Mesothelioma: ICD-O-3 histology code 9050–9055

  • Mesothelioma is a highly fatal cancer caused by exposure to asbestos.
  • The number of new cases of mesothelioma diagnosed each year in Ontario is rising.
  • The number of cases is expected to decline in the future due to decreased use of asbestos in Ontario.

Mesothelioma is a rare but highly fatal cancer. It affects the protective linings covering many of the body’s internal organs, most commonly the pleura, which cover the lungs. Almost all mesothelioma is caused by exposure to asbestos,2 the commercial term for a group of six naturally occurring mineral fibres. Asbestos has been used for many commercial applications, including insulation, textiles, roofing, brake pads and cement pipe. Approximately 85 per cent of mesothelioma cases in men and 40 per cent of cases in women are attributable to work-related asbestos exposure,2,3,4 while most of the remainder are caused by other environmental asbestos exposure,3 such as exposure to asbestos-containing insulation in the home, or family members’ exposure to trace asbestos on workers’ clothing. Asbestos also causes lung, ovarian and laryngeal cancer, as well as asbestosis (scarring of the lungs).5 Mesothelioma rates in Ontario are highest in Lambton County due to heavy historic use of asbestos in Sarnia’s Chemical Valley.6

Use of asbestos peaked in the 1960s and 1970s, and has declined significantly since then due to regulations and restrictions in use because of the adverse health effects.7 However, because mesothelioma takes a long time to develop, the current burden of disease is associated with asbestos exposure that occurred 10 to 50 years ago. The number of new cases of mesothelioma is expected to plateau and decline based on the pattern of decreased asbestos use, but it is difficult to predict when this will happen. Currently, new uses of asbestos in Canada are limited to friction products, cement and a small number of other specialized products. Most exposure today occurs when asbestos-containing materials in older buildings or other products deteriorate or are disturbed during maintenance, repair, or remediation. CAREX Canada, a national carcinogen surveillance program, has estimated that approximately 52,000 Ontarians are still exposed to asbestos in the workplace, most in the construction, automotive repair, remediation and ship building industries.8 Asbestos exposure today will impact the future burden of asbestos-related disease.

For more information, see:


  1. Statistics Canada. CANSIM Table 103-0553. New cases and age-standardized rate for primary cancer (based on the May 2015 CCR tabulation file), by cancer type and sex, Canada, provinces and territories. Available from
  2. Rake C, Gilham C, Hatch J, et al.  Occupational, domestic, and environmental mesothelioma risks in the British population: a case-control study. Br J Cancer. 2009;100:1075–83.
  3. Lacourt A, Gramond C, Rolland P, et al. Occupational and non-occupational attributable risk of asbestos exposure for malignant pleural mesothelioma. Thorax. 2014;69:532–9.
  4. Spirtas R, Heineman E, Bernstein L, et al. Malignant mesothelioma: Attributable risk of asbestos exposure. Occup Environ Med. 1994;51:804–11.
  5. IARC. Arsenic, Metals, Fibres and Dusts. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. 2012; 100C:219–94. Available from
  6. Kramer D, McMillan K, Gross E, et al. From Awareness to Action: The Community of Sarnia Mobilizes to Protect its Workers from Occupational Disease. New Solut. 2015;25(3):377–410.
  7. CAREX Canada. Asbestos – Profile. 2015. Available from
  8. CAREX Canada. Asbestos – Occupational Estimate. 2015. Available from

Posted November 2015

Citation: Material appearing in this Cancer Fact may be reproduced or copied without permission. The following citation must be used: Cancer Care Ontario. Cancer Fact:  Mesothelioma cases in Ontario continue to rise. Nov. 2015. Available at

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This Ontario Cancer Fact was prepared by staff in Prevention and Cancer Control.

Last modified: Mon, Nov 30, 2015
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