Asbestos-related cancers among 28,300 military servicemen in the Royal Norwegian Navy

Our plain-English summary of Asbestos-related cancers among 28,300 military servicemen in the Royal Norwegian Navy, by L.A. Strand, J.I. Martinsen, V.F. Koefoed, et al (American Journal of Industrial Medicine, 2010).

The study

• Authors: L.A. Strand, J.I. Martinsen, V.F. Koefoed, J. Sommerfelt-Pettersen, T.K. Grimsrud
• Journal: American Journal of Industrial Medicine
• Published: 2010;53(1):64-71
• Cited by: 22 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: This study focus on the incidence of asbestos-related cancers among 28,300 officers and enlisted servicemen in the Royal Norwegian Navy. Until 1987, asbestos aboard the vessels potentially caused exposure to 11,500 crew members.

Methods: Standardized incidence ratios (SIR) were calculated for malignant mesothelioma, lung cancer, and laryngeal, pharyngeal, stomach, and colorectal cancers according to service aboard between 1950 and 1987 and in other Navy personnel.

Results: Increased risk of mesothelioma was seen among engine room crews, with SIRs of 6.23 (95% CI = 2.51-12.8) and 6.49 (95% CI = 2.11-15.1) for personnel who served less than 2 years and those with longer service, respectively. Lung cancer was nearly 20% higher than expected among both engine crews and non-engine crews. An excess of colorectal cancer bordering on statistical significance was seen among non-engine crews (SIR = 1.14; 95% CI = 0.98-1.32). Land-based personnel and personnel who served aboard after 1987 had lower lung cancer incidence than expected (SIR = 0.77; 95% CI = 0.64-0.92). No elevated risk of laryngeal, pharyngeal, or stomach cancers was seen.

Conclusion: The overall increase (65%) in mesotheliomas among military Navy servicemen was confined to marine engine crews only. The mesothelioma incidence can be taken as an indicator of the presence or absence of asbestos exposure, but it offered no consistent explanation to the variation in incidence of other asbestos-related cancers.

(c) 2009 Wiley-Liss, Inc.

In plain English

This historical cohort study followed 28,345 male Royal Norwegian Navy officers and enlisted servicemen serving 1950–2004. Cancer Registry cases for 1953–2007 were compared with national male rates. About 11,500 who served aboard in 1950–1987 were regarded as asbestos-exposed, engine room crews more heavily; no personal exposure measurements existed. The cohort had 22 mesotheliomas, all pleural, against 13.3 expected. Engine room crews had raised mesothelioma rates: SIR 6.23 (95% CI 2.51–12.8; 7 cases) with under 2 years there, 6.49 (95% CI 2.11–15.2; 5 cases) with 2 years or more. Crews never in engine rooms and unexposed personnel had no excess. Lung cancer was raised in crews never in engine rooms (SIR 1.18; 95% CI 1.01–1.37) and below expected in unexposed personnel (SIR 0.77; 95% CI 0.64–0.92). Laryngeal, pharyngeal, stomach and colorectal cancers did not differ significantly from expected in any subgroup. The authors concluded that excess mesothelioma was confined to engine room crews and, using mesothelioma as the exposure indicator, the data did not suggest an effect on other airway, stomach or colorectal cancers. They had no smoking data.

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: Historical (retrospective) cohort study comparing observed cancer cases with national rates (standardized incidence ratios), plus Poisson regression comparing duty stations aboard ship
• Who was studied: 28,345 male commissioned and non-commissioned officers and enlisted servicemen of the Royal Norwegian Navy (Fleet, Coast Guard, Coastal Artillery) who served 1950–2004. Women (719) and conscripts who did not reach officer rank were excluded. Cancer follow-up ran from 1953 to 2007, totalling 889,190 person-years.
• Exposure: Service aboard Navy vessels (surface vessels and submarines) between 1950 and 1987 was treated as asbestos exposure. Engine room crews (machinist, engine, greaser, stoker, electrician job titles) were considered to have higher exposure intensity. Land-based service, and any service after 1987, was treated as unexposed. No personal-level asbestos measurements or records were available.
• Main results:
  • In the whole cohort there were 22 malignant mesotheliomas against 13.3 expected (SIR 1.65; 95% CI 1.04–2.50). All were pleural, diagnosed 1983–2007.
  • Engine room crews had a raised mesothelioma rate. Those with less than 2 years of engine room service had 7 cases (SIR 6.23; 95% CI 2.51–12.8). Those with 2 years or more had 5 cases (SIR 6.49; 95% CI 2.11–15.2). Crews who never served in the engine room had 5 cases (SIR 0.90; 95% CI 0.29–2.09).
  • In Poisson regression, mesothelioma rate ratios compared with ship crews who never served in the engine room were 6.76 (95% CI 2.14–21.3) for under 2 years and 7.26 (95% CI 2.10–25.1) for 2 years or more of engine room service. Duty station had no effect on lung cancer.
  • Personnel regarded as unexposed had no excess of mesothelioma (5 cases vs 5.8 expected; SIR 0.86; 95% CI 0.28–2.00). Their lung cancer incidence was lower than national rates (SIR 0.77; 95% CI 0.64–0.92).
  • Personnel with 2 years or more aboard vessels had 10 mesotheliomas (SIR 3.00; 95% CI 1.44–5.51) and raised lung cancer (SIR 1.24; 95% CI 1.03–1.50).
  • Lung cancer was similar in crews who never served in the engine room (SIR 1.18; 95% CI 1.01–1.37) and in engine room crews of any service length (SIR 1.19; 95% CI 0.91–1.55). Excess mesothelioma occurred only in the engine room crews.
  • Laryngeal, pharyngeal, stomach and colorectal cancers did not differ significantly from expected in any subgroup. Colorectal cancer among crews who never served in the engine room was SIR 1.14 (95% CI 0.98–1.32), described as bordering on statistical significance.
  • For the 12 mesothelioma cases among engine room crews, the median latency from first engine room job to diagnosis was 41 years (range 28 to 48 years). Engine room service in these cases ranged from 3 months to 6.3 years (median 1.3 years).
  • Among submariners, the suggested moderate increase in mesothelioma rested on two cases only.
• The authors' conclusion: The authors concluded that excess mesothelioma (only pleural cases were found) was seen among engine room crews aboard vessels. When mesothelioma was taken as an indicator of asbestos exposure, the data did not suggest an effect on other airway cancers, stomach cancer, or colorectal cancer.
• Limitations the authors state:
  • Navy service files from before 1950 were incomplete or missing because of WWII, which could misclassify duration of service and duty stations.
  • No individual data on smoking or asbestos exposure, which limited interpretation of the lung cancer results.
  • Asbestos exposure outside the Navy may have influenced the rates and obscured any effect of length of Navy service.
  • Because vessel crews typically moved to land-based jobs later in their careers, the contrast between exposed and unexposed may have been underestimated.
  • Follow-up was not lifetime, so the latency estimates may change with extended follow-up.
  • The authors had no data on lifetime asbestos exposure and lacked statistical strength to examine why no peritoneal mesotheliomas occurred.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, The Navy.

Medical terms in this study, explained in our Lexicon: Standardized Incidence Ratio (SIR), Mesothelioma, Lung Cancer, Colorectal Cancer, Statistical Significance, Stomach Cancer, Asbestos Exposure.

Related studies

• Variability in interpretation among B-readers in the U.S. Navy Asbestos Medical Surveillance Program — J.G. Muller, J.M. Lieske, et al. (2008)
• Trends in pleural radiographic findings in the Navy Asbestos Medical Surveillance Program (1990-1999) — J.G. Muller, B.K. Bohnker, et al. (2005)
• Mortality among United Kingdom servicemen who served abroad in the 1950s and 1960s — S.C. Darby, C.R. Muirhead, et al. (1990)
• Royal Naval dockyards asbestosis research project: nine-year follow-up study of men exposed to asbestos in Devonport Dockyard — C.E. Rossiter, J.R. Heath, et al. (1980)
• Incidence of cancer among Norwegian boiler welders — T.E. Danielsen, S. Langård, et al. (1996)
• Cancer incidence among seafarers and fishermen in the Nordic countries — K. Ugelvig Petersen, E. Pukkala, et al. (2020)

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