“Military aircrew and ground crew were overall more likely to be diagnosed with cancer, but less likely to die from cancer compared to the U.S. population,” the report concludes.
The study involved 156,050 aircrew and 737,891 ground crew. Participants were followed between 1992 and 2017. Both groups were predominantly male and non-Hispanic.
Data on cancer incidence and mortality for these two groups were compared with data from groups of similar age in the general population through use of the Surveillance, Epidemiology, and End Results (SEER) Database of the National Cancer Institute.
For aircrew, the study found an 87% higher rate of melanoma, a 39% higher rate of thyroid cancer, a 16% higher rate of prostate cancer, and a 24% higher rate of cancer for all sites combined.
A higher rate of melanoma and prostate cancer among aircrew has been reported previously, but the increased rate of thyroid cancer is a new finding, the authors note.
The uptick in melanoma has also been reported in studies of civilian pilots and cabin crew. It has been attributed to exposure to hazardous ultraviolet and cosmic radiation.
For ground crew members, the analysis found a 19% higher rate of cancers of the brain and nervous system, a 15% higher rate of thyroid cancer, a 9% higher rate of melanoma and of kidney and renal pelvis cancers, and a 3% higher rate of cancer for all sites combined.
There is little to compare these findings with: This is the first time that cancer risk has been evaluated in such a large population of military ground crew.
Lower rates of cancer mortality
In contrast to the increase in cancer incidence, the report found a decrease in cancer mortality.
When compared with a demographically similar U.S. population, the mortality rate among aircrew was 56% lower for all cancer sites; for ground crew, the mortality rate was 35% lower.
However, the report authors emphasize that “it is important to note that the military study population was relatively young.”
The median age at the end of follow-up for the cancer incidence analysis was 41 years for aircrew and 26 years for ground crew. The median age at the end of follow-up for the cancer mortality analysis was 48 years for aircrew and 41 years for ground crew.
“Results may have differed if additional older former Service members had been included in the study, since cancer risk and mortality rates increase with age,” the authors comment.
Other studies have found an increase in deaths from melanoma as well as an increase in the incidence of melanoma. A meta-analysis published in 2019 in the British Journal of Dermatology found that airline pilots and cabin crew have about twice the risk of melanoma and other skin cancers than the general population. Pilots are also more likely to die from melanoma.
Further study underway
The findings on military air and ground crew come from phase 1 of a study that was required by Congress in the 2021 defense bill. Because the investigators found an increase in the incidence of cancer, phase 2 of the study is now necessary.
The report authors explain that phase 2 will consist of identifying the carcinogenic toxicants or hazardous materials associated with military flight operations; identifying operating environments that could be associated with increased amounts of ionizing and nonionizing radiation; identifying specific duties, dates of service, and types of aircraft flown that could have increased the risk for cancer; identifying duty locations associated with a higher incidence of cancers; identifying potential exposures through military service that are not related to aviation; and determining the appropriate age to begin screening military aircrew and ground crew for cancers.
A version of this article first appeared on Medscape.com.