Cause-specific mortality and cancer incidence among 28 300 Royal Norwegian Navy servicemen followed for more than 50 years

Abstract

OBJECTIVES: The aim of this study was to examine mortality and cancer incidence in a cohort of 28 300 military servicemen known, from personnel files, to have served in the Royal Norwegian Navy during 1950–2004. METHODS: The cohort was followed from 1951–2007 for mortality and from 1953–2008 for cancer. Standardized mortality ratios (SMR) and incidence ratios (SIR) for cancer were calculated from national rates. Internal comparisons [rate ratios (RR)] were made using Poisson regression. RESULTS: Mortality for all Navy personnel was lower than expected for all causes combined (SMR 0.84) and for most disease groups and violent causes, but not for cancer mortality (SMR 1.02). Vessel crews had consistently higher SMR than land-based personnel, still with rates lower than – or close to – national ones. The relative risk between the two subgroups was in the same direction for mortality from alcohol abuse and non-malignant alcohol-related diseases (RR 1.56) and for the incidence of alcohol-related cancers (RR 1.58) and lung cancer (RR 1.65). An overall small excess in the incidence of all cancers combined for the entire cohort (SIR 1.06) was caused by prostate cancer, malignant melanoma, and non-melanoma skin cancer. An excess of bladder cancer was observed among submariners (SIR 1.53). CONCLUSION: The low all-cause mortality was in line with a “healthy soldier effect”. Navy personnel had a lower-than-expected mortality from accidents and suicide. Alcohol-related diseases were more frequent among vessel crews than among land-based personnel, but largely comparable to the rates among all Norwegian men.

Keywords

• military
• violent death
• royal norwegian navy
• navy
• submariner
• vessel crew
• cancer incidence
• mortality
• cohort study
• alcohol