Our search yielded no aggregate studies to determine if there is an increased rate of other types of skin cancer in military service members such as Merkel cell carcinoma, dermatofibrosarcoma protuberans, and microcystic adnexal carcinoma (MAC). Gerall et al10 described a case of MAC in a 43-year-old USAF U-2 pilot with a 15-year history of a slow-growing soft-tissue nodule on the cheek. The patient’s young age differed from the typical age of MAC occurrence (ie, 60–70 years), which led to the possibility that his profession contributed to the development of MAC and the relatively young age of onset.10
Etiology of Disease
The results of our literature review indicated that skin cancers are more prevalent among active-duty military personnel and veterans than in the general population; they also suggest that frequent sun exposure and lack of sun protection may be key etiologic factors. In 2015, only 23% of veterans (n=49) reported receiving skin cancer awareness education from the US Military.1 Among soldiers returning from Iraq and Afghanistan (n=212), only 13% reported routine sunscreen use, and less than 30% reported having routine access to sunscreen while working more than 4 hours per day in direct sunlight or 75% of the day working in direct sunlight. Of these, the majority reported sustaining at least 1 sunburn, while 43% had at least 2 sunburns and 20% reported a history of a blistering sunburn during deployment.1 The intermittent exposure hypothesis—defined as the theory that intense periods of exposure to UV radiation increase the risk for melanoma more than chronic cumulative UV radiation exposure—may explain how occupational exposure in the military may lead to increased skin cancer incidence. Individuals exposed to brief periods of intense, inconsistent, or unpredictable UV radiation may lack protective adaptive mechanisms compared to those who are chronically exposed.2
Exposure to UV radiation at higher altitudes (with corresponding higher UV energy) and altered sleep-wake cycles (with resulting altered immune defenses) may contribute to higher rates of melanoma and NMSC among USAF pilots.11 During a 57-minute flight at 30,000-ft altitude, a pilot is exposed to a UVA dose equivalent to 20 minutes inside a tanning booth.12 Although UVB transmission through plastic and glass windshields was reported to be less than 1%, UVA transmission ranged from 0.4% to 53.5%. The UVA dose for a pilot flying a light aircraft in Las Vegas, Nevada, was reported to be 127 μW/cm2 at ground level vs 242 μW/cm2 at a 30,000-ft altitude.12 Therefore, cosmic radiation exposure for military pilots is higher than for commercial pilots, as they fly at higher altitudes. U-2 pilots are exposed to 20 times the cosmic radiation dose at sea level and 10 times the exposure of commercial pilots.10
It currently is unknown why service in the USAF would increase skin cancer risk compared to service in other branches; however, there are some differences between military branches that require further research, including ethnic demographics, uniform wear and personal protective equipment standards, duty assignment locations, and the hours the military members are asked to work outside with direct sunlight exposure for each branch of service. Environmental exposures may differ based on the military branch gear requirements; for example, when on the flight line or flight deck, USN aircrews are required to wear cranials (helmets), eyewear (visor or goggles), and long-sleeved shirts. When at sea, USN flight crews wear gloves, headgear, goggles, pants, and long-sleeved shirts to identify their duty onboard. All of these measures offer good sun protection and are carried over to the land-based flight lines in the USN and Marine Corps. Neither the Army nor the USAF commonly utilize these practices. Conversely, the USAF does not allow flight line workers including fuelers, maintainers, and aircrew to wear coveralls due to the risk of being blown off, becoming foreign object debris, and being sucked into jet engines. However, in-flight protective gear such as goggles, gloves, and coveralls are worn.12 Perhaps the USAF may attract, recruit, or commission people with inherently more risk for skin cancer (eg, White individuals). How racial and ethnic factors may affect skin cancer incidence in military branches is an area for future research efforts.
Recommendations
Given the considerable increase in risk factors, efforts are needed to reduce the disparity in skin cancer rates between US military personnel and their civilian counterparts through appropriate prevention, screening, and intervention programs.
Prevention—In wartime settings as well as in training and other peacetime activities, active-duty military members cannot avoid harmful midday sun exposure. Additionally, application and reapplication of sunscreen can be challenging. Sunscreen, broad-spectrum lip balm, and wide-brimmed “boonie” hats can be ordered by supply personnel.13 We recommend that a standard sunscreen supply be available to all active-duty military service members. The long-sleeved, tightly woven fabric of military uniforms also can provide protection from the sun but can be difficult to tolerate for extended periods of time in warm climates. Breathable, lightweight, sun-protective clothing is commercially available and could be incorporated into military uniforms.
All service members should be educated about skin cancer risks while addressing common myths and inaccuracies. Fifty percent (n=50) of surveyed veterans thought discussions of skin cancer prevention and safety during basic training could help prevent skin cancer in service members.14 Suggestions from respondents included education about sun exposure consequences, use of graphic images of skin cancer in teaching, providing protective clothing and sunscreen to active-duty military service members, and discussion about sun protection with physicians during annual physicals. When veterans with a history of skin cancer were surveyed about their personal risk for skin cancer, most believed they were at little risk (average perceived risk response score, 2.2 out of 5 [1=no risk; 5=high risk]).14 The majority explained that they did not seek sun protection after warnings of skin cancer risk because they did not think skin cancer would happen to them,14 though the incidence of NMSC in the United States at the time of these surveys was estimated to be 3.5 million per year.14,15 Another study found that only 13% of veterans knew the back is the most common site of melanoma in men.1 The Army Public Health Center has informational fact sheets available online or in dermatologists’ offices that detail correct sunscreen application techniques and how to reduce sun exposure.16,17 However, military service members reported that they prefer physicians to communicate with them directly about skin cancer risks vs reading brochures in physician offices or gaining information from television, radio, military training, or the Internet (4.4 out 5 rating for communication methods of risks associated with skin cancer [1=ineffective; 5=very effective]).14 However, only 27% of nondermatologist physicians counseled or screened their patients on skin cancer or sunscreen yearly, 49% even less frequently, with 24% never counseling or screening at all. Because not all service members may be able to regularly see a dermatologist, efforts should be focused on increasing primary care physician awareness on counseling and screening.18