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.

Social and life skills in adolescents who have self-harmed: analysis of survey responses from a national sample of adolescents in Norway

OBJECTIVE

Social and life skills (SLS) may be important in the prevention and treatment of self-harm, but few studies have described this relationship. We examined three components of SLS in adolescents who reported self-harm that was, according to themselves, diagnosed by a clinician.

DESIGN

Cross-sectional.

SETTING

National screening prior to military service.

PARTICIPANTS

176 284 residents of Norway born in 1999-2001 received a declaration of health. We included 171 486 individuals (84 153 (49%) women and 87 333 (51%) men) who were 17 (n=1 67 855) or 18 years of age (n=3631) when they completed the declaration.

OUTCOME MEASURE

The main outcome was clinically diagnosed self-harm, defined as self-harm that the adolescents themselves stated had been diagnosed by a clinician. Components of SLS were social interactions; coping strategies; and emotional regulation/aggression. The association between SLS and self-reported clinically diagnosed self-harm was assessed in hierarchical multiple regression models controlling for sex; school absence; and feelings of emotional pain.

RESULTS

Three percent (n=5507) of the adolescents reported clinically diagnosed self-harm. The three components of SLS together added little to the prediction of clinically diagnosed self-harm (∆R²=0.02). After controlling for school absence and emotional pain, emotional regulation/aggression was the only SLS-component that was independently associated with clinically diagnosed self-harm (OR 1.33, 95% CI 1.31 to 1.36). The young men who said they had been clinically diagnosed for self-harm scored slightly worse on social interactions (Hedge's g (g) = -0.13, p<0.001) and emotional regulation/aggression (g = -0.18, p<0.001) than the young women in this group.

CONCLUSION

Young women and young men who reported clinically diagnosed self-harm had more problems with emotional regulation/aggression than other adolescents, but did not have worse social interactions or coping strategies.

Temporal trends in the healthy soldier effect in a cohort of Royal Norwegian Navy servicemen followed for 67 years

OBJECTIVES

To investigate temporal trends in the 'healthy soldier effect' (HSE) among 28 300 Royal Norwegian Navy servicemen who served during 1950-2004.

METHODS

Standardised mortality ratios (SMRs) for all causes, diseases and external causes were calculated from national rates for the entire study period (1951-2017), and for seven successive follow-up periods after the first recorded day of Naval service, for the overall cohort and for two subgroups: land-based personnel and vessel crews. Poisson regression, expressed as rate ratios, was used to compare all-cause mortality between the subgroups.

RESULTS

In the overall cohort, SMRs for all-cause mortality increased steadily during the first six 10-year follow-up periods, from 0.52 to 0.94, which was still lower than national rates. After 60 years, the lower mortality compared with national rates was no longer statistically significant (SMR=0.93). Low non-neoplastic disease mortality contributed most to the longevity of the HSE. For neoplastic diseases, there was a mortality deficit only for the first and third 10-year follow-up periods. External-cause mortality rose to national rates after 40 years. An HSE was present among vessel crews, but their total mortality rate was 24% higher than that among land-based personnel, who also showed a longer-lasting HSE.

CONCLUSIONS

The HSE eroded gradually over time but was still present at 60 years of follow-up for all-cause mortality. The effect was strongest and most long-lived for non-neoplastic disease, lasted up to 40 years for external causes, and was relatively short for cancers. Land-based personnel showed stronger and longer-lasting HSE than vessel crews.

A 5-Year Continued Follow-up of Cancer Risk and All-Cause Mortality Among Norwegian Military Peacekeepers Deployed to Kosovo During 1999-2016

INTRODUCTION

In 2012, Norwegian news media reported on cases of brain cancer among Norwegian peacekeeping troops who served in Kosovo, allegedly caused by exposure to depleted uranium fired during airstrikes before the peacekeepers arrived in 1999. A first study followed 6076 military men and women with peacekeeping service in Kosovo during 1999-2011 for cancers and deaths throughout 2011. The study did not support to the idea that peacekeeping service in Kosovo could lead to increased risk of brain cancer or other cancers. However, the average time of follow-up (10.6 years) was rather short for cancer development; therefore the aim of the present study was to evaluate cancer risk and general mortality in an updated cohort after 5 years of additional follow-up.

MATERIALS AND METHODS

The updated cohort consisted of 6,159 peacekeepers (5,884 men and 275 women) who served in Kosovo during 1999-2016 and were followed for cancer incidence and mortality from all causes combined throughout 2016. We calculated standardized incidence ratios (SIR) for cancer and standardized mortality ratios (SMR) from national population rates. Poisson regression was used to assess the effect of length of service (<1 year vs. ≥1 year) on cancer risk.

RESULTS

We observed 149 cancer cases and 75 deaths in the updated cohort. Observed cancer incidence did not exceed national rates. In men, the SIR for brain cancer was 0.73 (95% confidence interval (CI) 0.32-1.44), based on eight cases, while the risk of colon cancer was lowered (SIR = 0.14, 95% CI 0.00-0.79). The Poisson regression showed no effect of service duration on all-site cancer incidence. Mortality from all causes combined was lower than expected (SMR = 0.62, 95% CI 0.49-0.78) and in accordance with a "healthy soldier effect".

CONCLUSION

The extended follow-up did not give support to the suggestion that peacekeeping service in Kosovo could lead to increased risk of cancer.

External-cause mortality among 21 609 Norwegian male military peacekeepers deployed to Lebanon between 1978 and 1998

OBJECTIVE

To investigate external-cause mortality among 21 609 Norwegian male military peacekeepers deployed to Lebanon during 1978-1998.

METHODS

The cohort was followed from the 1st day of deployment through 2013, and mortality during deployment and post discharge was assessed using SMRs calculated from national rates in Norway. Poisson regression was used to see the effect of high-conflict versus low-conflict exposure.

RESULTS

For the total cohort, external-cause mortality was within expected values during deployment (SMR=0.80) and post discharge (SMR=1.05). In the low-conflict exposure group, a lower mortality from all external causes (SMR=0.77), transport accidents (SMR=0.55) and accidental poisoning (SMR=0.53) was seen. The high-conflict exposure group showed an elevated mortality from all external causes (SMR=1.20), transport accidents (SMR=1.51) and suicide (SMR=1.30), but these risks were elevated only during the first 5 years after discharge. This group also showed elevated mortality from all external causes (rate ratio, RR=1.49), and for transport accidents (RR=3.30) when compared with the low-conflict exposure group.

CONCLUSIONS

Overall external-cause mortality among our peacekeepers was equal to national rates during deployment and post discharge. High-conflict exposure was associated with elevated mortality from all external causes, transport accidents and suicide during the first 5 years after discharge from service.

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

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.