Recent trends in incidence rates of pleural mesothelioma in British Columbia

Our plain-English summary of Recent trends in incidence rates of pleural mesothelioma in British Columbia, by H.I. Morrison, P.R. Band, R. Gallagher, et al (Canadian Medical Association Journal, 1984).

The study

• Authors: H.I. Morrison, P.R. Band, R. Gallagher, J. Spinelli, D.T. Wigle
• Journal: Canadian Medical Association Journal
• Published: 1984;131(9):1069-71
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 001654).

Abstract

A total of 64 cases of pleural mesothelioma were reported in British Columbia between 1973 and 1980, 54 in males and 10 in females. There was a significant (p less than 0.05) increase in the incidence among males. The overall incidence rates were 4.9 and 0.9 per million person-years for males and females respectively. The age distribution of the cases was roughly exponential up to age 70 years. Almost all of the cases were clustered in Cowichan Valley, Capital and Greater Vancouver counties, where there was a high level of shipbuilding activity 30 to 40 years ago. The increased incidence in males may be related to this activity, which involved exposure to asbestos.

In plain English

This study used cancer registry records to examine pleural mesothelioma (cancer of the lining around the lungs) diagnosed in British Columbia from 1973 through 1980. There were 64 reported cases, 54 in males and 10 in females, giving overall rates of 4.9 per million person-years for males and 0.9 for females. Among males the age-standardized yearly rate increased significantly (p less than 0.05), from 3.2 per million in 1973 to 7.9 in 1980. Females showed no significant trend. Rates rose roughly exponentially with age up to 70, and at age 70 and older the rate was 31.6 per million in men versus 0 in women. The authors reported that almost all cases were clustered in Cowichan Valley, Capital and Greater Vancouver counties, where male rates were 13.7, 12.5 and 4.2 per million, compared with 3.1 in all other counties. The study did not record individual asbestos exposure. The authors suggested the male increase may be at least partly related to shipbuilding activity on the west coast 30 to 40 years earlier, but said a case-control study is needed to assess this.

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: Descriptive study of incidence trends using cancer registry data, with record linkage to death certificates and mortality data
• Who was studied: All 64 cases of pleural mesothelioma (54 males, 10 females) diagnosed in British Columbia from 1973 through 1980 and reported to the National Cancer Incidence Reporting System of Statistics Canada
• Exposure: No individual exposure data were collected. Cases were grouped by county of residence. The authors compared this with census figures on the share of the male labour force in shipbuilding and ship repair in 1941 and 1951: Vancouver 1.9% and 1.4%, Victoria 3.9% and 3.5%, all of Canada 0.5% in both years.
• Main results:
  • 64 cases of pleural mesothelioma were reported in British Columbia from 1973 to 1980: 54 in males and 10 in females.
  • Overall incidence rates were 4.9 per million person-years for males and 0.9 for females.
  • Linear regression showed a significant increase in incidence among males (p less than 0.05) and no significant trend among females.
  • Among males, the age-standardized rate was 3.2 per million (4 cases) in 1973 and 7.9 per million (12 cases) in 1980.
  • Almost all cases were clustered in Cowichan Valley, Capital and Greater Vancouver counties. No other county had more than three cases.
  • Age-standardized male rates per million (with case counts) were: Cowichan Valley 13.7 (3), Capital 12.5 (15), Greater Vancouver 4.2 (22), all other counties 3.1 (14). Female rates were 5.4 (1), 2.8 (3), 1.0 (4) and 0.4 (2).
  • Age-specific rates rose roughly exponentially up to age 70, with few cases below age 45. At age 70 and older the rate was 31.6 per million for men (18 cases) and 0 for women.
  • The male-to-female ratio of incidence rates in this study was 5.4. The authors said this high ratio is consistent with occupational asbestos exposure among the males.
  • Of 51 male cases with death certificates found, the recorded cause of death was pleural cancer in 61% (31) and other respiratory tract cancers, mainly lung cancer, in 33% (17).
  • Of 28 deaths attributed to pleural cancer in 1973 to 1977, only 13 (46%) could be confirmed as mesothelioma by linkage to the incidence registry. 2 of the 28 were not found in the registry.
• The authors' conclusion: The authors concluded that reported pleural mesothelioma rates in British Columbia males have increased, and that rates were particularly high in the greater Victoria area. They wrote that it may be reasonable to surmise the increase is at least partially related to west coast shipbuilding in the 1940s and 1950s, but that a case-control study is needed to assess this hypothesis. They also concluded that death records would be a poor substitute for incidence records for estimating these rates.
• Limitations the authors state:
  • The cause of the increased county rates was not known. The shipbuilding link was a possibility the authors raised, not something the study tested.
  • Linkage of deaths to the incidence registry was limited to 1973 to 1977, because individual incidence records on microfiche ended in 1977.
  • Shipbuilding labour force data were not available by county.

Topics

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

Medical terms in this study, explained in our Lexicon: Incidence, Pleural Mesothelioma.

Related studies

• Cohort mortality study of pulp and paper mill workers in British Columbia, Canada — P.R. Band, N.D. Le, et al. (1997)
• Identification of occupational cancer risk in British Columbia: a population-based case-control study of 2,998 lung cancers by histopathological subtype — A.C. MacArthur, N.D. Le, et al. (2009)
• Malignant mesothelioma in British Columbia in 1982 — A. Churg (1985)
• Surveillance of mesothelioma and workers' compensation in British Columbia, Canada — T.L. Kirkham, M.W. Koehoorn, et al. (2011)
• Identification of occupational cancer risks in British Columbia, Canada: a population-based case-control study of 1,155 cases of colon cancer — R. Fang, N. Le, et al. (2011)
• Acid leaching studies of chrysotile asbestos from mines in the Coalinga region of California and from Quebec and British Columbia — A. Morgan (1997)

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