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Original research
Lifelong differences in cancer incidence and mortality between subgroups of similar socioeconomic status in the Royal Norwegian Navy
  1. Leif Aage Strand1,
  2. Inger Rudvin1,
  3. Jan Ivar Martinsen2,
  4. Elin Anita Fadum1,3,
  5. Tom K Grimsrud2
  1. 1 Institute of Military Epidemiology, Norwegian Armed Forces Joint Medical Services, Ullensaker, Norway
  2. 2 Institute of Population based Cancer Research, Cancer Registry of Norway, Oslo, Norway
  3. 3 Institute for Studies of the Medical Profession, Oslo, Norway
  1. Correspondence to Dr Leif Aage Strand, Institute of Military Epidemiology, Norwegian Armed Forces Joint Medical Services, Ullensaker, N-2058 Sessvollmoen, Norway; laastrand{at}forsvaretshelseregister.no

Abstract

Objectives In a previous cohort study of 28 300 Navy servicemen, vessel crews showed higher cancer incidence and mortality than did land-based personnel. We have extended the follow-up to look for changes in cancer risk, and to explore temporal trends in cancer incidence and cancer mortality during more than six decades of follow-up.

Methods Cancer incidence and total cancer mortality were compared with the general population by calculating standardised ratios (standardised incidence ratios (SIRs), standardised mortality ratios) for the entire follow-up, with temporal trends through seven consecutive 10-year time spans from individual entry to follow-up. Rates were compared between the subgroups using Poisson regression, expressed as rate ratios (RRs).

Results Cancer incidence in Navy servicemen suggested a healthy soldier effect limited to the first three decades of follow-up and confined to land-based personnel. Overall, vessel crews showed 13% higher cancer incidence and 36% higher cancer mortality than other Navy servicemen. Some of the differences may be explained by a higher risk in vessel crews of cancers known to have less than 25% 5-year relative survival (RR=1.71), such as cancers of the lung, liver, pancreas and mesothelioma.

Conclusion Through most of the observation time, vessel crews had an overall cancer SIR that was higher than that of land-based personnel. Much of this excess involved cancers with a generally poor prognosis, linked to lifestyle and work environment. The contrasts in cancer incidence and mortality between the two subgroups of Navy servicemen persisted through more than six decades.

  • Cancer
  • Epidemiology
  • Occupational Health
  • Military Personnel
  • Men

Data availability statement

Data are available upon reasonable request. The data that support the findings of this study are available from the Norwegian Armed Forces Health Registry, but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors on reasonable request and with permission of the Norwegian Armed Forces Health Registry.

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Data availability statement

Data are available upon reasonable request. The data that support the findings of this study are available from the Norwegian Armed Forces Health Registry, but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors on reasonable request and with permission of the Norwegian Armed Forces Health Registry.

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Footnotes

  • Contributors The study was designed by LAS and TKG. IR and JIM performed the statistical analyses, and quality control of data and algorithms was performed by IR, JIM and LAS. The figure was created by EAF. LAS wrote the first draft of the manuscript and is the guarantor of the manuscript. All authors interpreted the data and revised the manuscript carefully. All authors approved the final version of the manuscript, and LAS had the final responsibility to submit the manuscript.

  • Funding This study was funded by the Norwegian Armed Forces Joint Medical Services. No external financial support was received.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.