Objectives Cancer incidence and mortality are important outcomes in the surveillance of long-term astronaut health. We compare cancer incidence rates, cancer-specific mortality rates, and cancer case-fatality ratios in US astronauts with those in the US general population.
Methods We use standardised incidence ratios (SIRs) and standardised mortality ratios (SMRs) to index the incidence and mortality of various cancers against rates in the US general population, from the US astronaut cohort inception in April 1959 through 31 December 2017. We compare the lethality of these cancers using the relative case-fatality ratio.
Results Overall cancer incidence and mortality were slightly lower than expected from national rates with SIR 82 (95% CI 63 to 104) and SMR 72 (95% CI 44 to 111) with a modest 14% reduction in case-fatality ratio. Prostate cancer and melanoma skin cancer had significant increases in incidence, with SIR of 162 (95% CI 109 to 232) and 252 (95% CI 126 to 452), respectively, though only melanoma had a significant increase in mortality, with SMR 508 (95% CI 105 to 1485). Lung cancer had a significant deficit of both cases and deaths, while colon cancer had sizeable (but not significant) reductions in incidence and mortality.
Conclusions The increase in incidence of melanoma is consistent with that observed in aircraft pilots, suggesting this may be associated with ultraviolet radiation or lifestyle factors rather than any astronaut-specific exposure. Reductions in lung cancer incidence and mortality, and trends towards such reductions in colon cancer, may be explained in part by healthy lifestyle, as well as differential screening among astronauts.
- occupational health
- aerospace medicine
Data availability statement
All data used in this study were collected from publicly available data sources, including the website of the US National Aeronautics and Space Administration (NASA).
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Contributors RR conceived the study and collected the data; RR, MPL and SD designed and performed the statistical analysis; all authors contributed to the writing and editing of the manuscript.
Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. However, the authors were supported in their work by the following: Mortality Research & Consulting. The Translational Research Institute for Space Health through NASA Cooperative Agreement NNX16AO69A. The Intramural Research Programme of the National Institutes of Health, National Cancer Institute, Division of Cancer Epidemiology and Genetics. The Human Research Programme of the Human Exploration and Operations Mission Directorate of the National Aeronautics and Space Administration. The NASA Human Health and Performance contract NNJ15HK11B.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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