Identification of occupational cancer risk in British Columbia: a population-based case-control study of 2,998 lung cancers by histopathological subtype

Our plain-English summary of Identification of occupational cancer risk in British Columbia: a population-based case-control study of 2,998 lung cancers by histopathological subtype, by A.C. MacArthur, N.D. Le, R. Fang, et al (American Journal of Industrial Medicine, 2009).

The study

• Authors: A.C. MacArthur, N.D. Le, R. Fang, P.R. Band
• Journal: American Journal of Industrial Medicine
• Published: 2009;52(3):221-32
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Few studies have investigated occupational lung cancer risk in relation to specific histopathological subtypes.

Methods: A case-control study was conducted to evaluate the relationship between lung cancer and occupation/industry of employment by histopathological subtype. A total of 2,998 male cases and 10,223 cancer controls, diagnosed between 1983 and 1990, were identified through the British Columbia Cancer Registry. Matched on age and year of diagnosis, conditional logistic regression analyses were performed for two different estimates of exposure with adjustment for potentially important confounding variables, including tobacco smoking, alcohol consumption, marital status, educational attainment, and questionnaire respondent.

Results: For all lung cancers, an excess risk was observed for workers in the primary metal (OR = 1.31, 95% CI, 1.01-1.71), mining (OR = 1.53, 95% CI, 1.20-1.96), machining (OR = 1.33, 95% CI, 1.09-1.63), transport (OR = 1.50, 95% CI, 1.08-2.07), utility (OR = 1.60, 95% CI, 1.22-2.09), and protective services (OR = 1.27, 95% CI, 1.05-1.55) industries. Associations with histopathological subtypes included an increased risk of squamous cell carcinoma in construction trades (OR = 1.25, 95% CI, 1.06-1.48), adenocarcinoma for professional workers in medicine and health (OR = 1.73, 95% CI, 1.18-2.53), small cell carcinoma in railway (OR = 1.62, 95% CI, 1.06-2.49), and truck transport industries (OR = 1.51, 95% CI, 1.00-2.28), and large cell carcinoma for employment in the primary metal industry (OR = 2.35, 95% CI, 1.11-4.96).

Conclusions: Our results point to excess lung cancer risk for occupations involving exposure to metals, polyaromatic hydrocarbons and asbestos, as well as several new histopathologic-specific associations that merit further investigation.

In plain English

This population-based case-control study compared the jobs of 2,964 men diagnosed with lung cancer in British Columbia from 1983 to 1990 with those of 10,223 men with other cancers, matched by age and year of diagnosis. Job histories, smoking and drinking came from questionnaires; no workplace exposures, including asbestos, were measured. Adjusted for smoking and other factors, odds ratios for all lung cancers were raised for usual work in mining (1.53; 90% confidence interval 1.20–1.96), primary metal industry (1.31; 1.01–1.71), water transport (1.50; 1.08–2.07), other utilities (1.60; 1.22–2.09) and protective services (1.27; 1.05–1.55). By cancer type, squamous cell carcinoma was linked to construction trades (1.25; 1.06–1.48), adenocarcinoma to medicine and health jobs (1.73; 1.18–2.53), small cell carcinoma to rail (1.62; 1.06–2.49) and truck transport (1.51; 1.00–2.28), and large cell carcinoma to primary metal industry (2.35; 1.11–4.96; 6 cases). The authors concluded that the results suggested excess risk in jobs involving metals, polyaromatic hydrocarbons and asbestos. They cautioned that exposure data were lacking, that chance from many comparisons may explain some findings, and that cancer-patient controls may cause bias.

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: Population-based case-control study. Lung cancer cases were matched on exact age and year of diagnosis to controls who had other cancers, and the data were analyzed with conditional logistic regression.
• Who was studied: Men aged 20 and older diagnosed with cancer in British Columbia, Canada, from 1983 to 1990, identified through the British Columbia Cancer Registry. Questionnaires were returned by 2,998 of 5,528 eligible lung cancer cases (54.2%). 2,964 of these cases were matched to 10,223 controls with other cancers. Cases by subtype: squamous cell 1,110, adenocarcinoma 898, small cell 549, large cell 166.
• Exposure: Self-reported lifetime occupation and industry titles, coded to Canadian standard classifications. These were analyzed as 'usual' job (longest held) and 'ever' job. No fiber types or doses were measured. Asbestos, metals and other agents were raised only as possible explanations.
• Main results:
  • All lung cancers, usual industry: the primary metal industry had OR 1.31 (CI 1.01 to 1.71; 74 cases) and the mining industry had OR 1.53 (CI 1.20 to 1.96; 89 cases). The tables label these intervals 90% CI, but the abstract calls them 95% CI.
  • All lung cancers: 'transport' had OR 1.50 (90% CI 1.08 to 2.07). Table IV lists this as the water transport industry, with 47 cases.
  • All lung cancers: the 'other utility' industry had OR 1.60 (90% CI 1.22 to 2.09; 76 cases). Protective services had OR 1.27 (90% CI 1.05 to 1.55; 132 cases); Table IV lists protective services as an occupation.
  • Squamous cell carcinoma: construction trades occupations had OR 1.25 (90% CI 1.06 to 1.48; 160 cases).
  • Adenocarcinoma: medicine and health occupations had OR 1.73 (90% CI 1.18 to 2.53; 24 cases).
  • Small cell carcinoma: the rail transport industry had OR 1.62 (90% CI 1.06 to 2.49; 21 cases) and the truck transport industry had OR 1.51 (90% CI 1.00 to 2.28; 24 cases).
  • Large cell carcinoma: the primary metal industry had OR 2.35 (90% CI 1.11 to 4.96), based on 6 cases.
  • Squamous cell carcinoma: electrical equipment installing and repair workers had OR 1.68 (90% CI 1.00 to 2.83; 14 cases). The authors attributed this to probable asbestos exposure, which was not measured.
  • Insulators were among the occupations with an elevated risk of adenocarcinoma. Their figures are not in the tables printed in the article and are said to be in online appendices.
  • All lung cancers: deck crew on ships had OR 3.77 (90% CI 1.92 to 7.41; 17 cases). The authors suggested ship emissions or asbestos used in shipbuilding as possible explanations.
• The authors' conclusion: The authors concluded that their results agreed with the literature and suggested excess lung cancer risk for occupations involving exposure to metals, polyaromatic hydrocarbons, asbestos, and concrete or wood dusts. They also reported several subtype-specific associations that call for further study.
• Limitations the authors state:
  • The study had no information on actual occupational exposures.
  • Statistically significant results may have occurred by chance because many comparisons were made (679 associations). Case numbers were small for many associations, especially for large cell carcinoma.
  • Using patients with other cancers as controls may have biased the results.

Topics

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

Medical terms in this study, explained in our Lexicon: Case-Control Study, Lung Cancer, Cancer Registry, Confounding, Squamous Cell Carcinoma, Adenocarcinoma, Carcinoma.

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