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Original research
Lifelong differences in cancer incidence and mortality between subgroups of similar socioeconomic status in the Royal Norwegian Navy


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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