U.S. Air Force Maj. Shannon Buck, a dermatologist at Landstuhl Regional Medical Center in Germany, performs a surgical procedure on a patient last year. Buck, who is also a Mohs surgeon, is reintroducing Mohs surgery services to LRMC after decades of nonavailability. Mohs surgery is considered the most effective technique for treating many basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs), the two most common types of skin cancer. Photo by Marcy Sanchez.
BETHESDA, MD — Since the 1990s, both melanoma and nonmelanoma skin cancer have become more prevalent in the United States. Across the nation, more than 9,500 people are diagnosed with skin cancer every day.
Understanding skin cancer risk is critical to the success of effective, targeted screening programs that could reduce mortality. While previous analyses of skin biopsy data have shown a correlation between skin cancer risk and various independent variables, until now, no studies have directly assessed skin malignancy risks for military personnel.1
“Nonmelanoma skin cancer is the most common cancer to affect humans; however, it typically does so in mid- or late-life and is not typically life threatening. Melanoma, while less common, is one of the deadliest cancers overall and it also can affect younger adults,” explained Jon Meyerle, MD, a dermatologist and the retired chief of immuno-dermatology at Walter Reed National Military Medical Center. “That makes it particularly relevant to the military population,” whose demographics skew younger.
Meyerle is the senior author of a new study published in the journal Military Medicine that aimed to characterize the impact of several variables on skin cancer risk for military personnel.2 The study also examined the association between biopsy rates and melanoma incidence in the military. The number needed to biopsy (NNB) quantifies the number of benign biopsies that occur in the course of identifying melanoma.
NNB is important to understand because biopsy of benign lesions represents potential harm for patients, both financially and physically. In addition, the U.S. Preventive Services Task Force recommends skin cancer screening only for certain groups—adults who have signs or symptoms of skin cancer, have had skin cancer previously or have a high risk of skin cancer—and it’s critical for clinicians to be able to accurately assess individual patient risks before proceeding with skin biopsy. Analyzing the relationship between military-specific demographics and skin biopsy yields could produce more targeted screenings programs for servicemembers.3
Biopsy Resources
“In general, the recognition of skin cancer is not perfect,” said Meyerle. “However, the goal is always to find the skin cancer and not waste resources on doing biopsies that turn out not to be malignant.”
The research team analyzed one year of skin biopsy pathology reports (from August 2015 to July 2016) from the WRNMMC dermatology clinic. They focused only on biopsies performed to rule out basal cell carcinoma, squamous cell carcinoma, or melanoma, and excluded malignant diagnoses that were exceedingly rare or could mimic other conditions. The researchers then obtained the patients’ age, gender, military beneficiary status, branch of service and military rank category from electronic health records.
Of the 5,391 biopsies performed during the study period, a total of 3,098 biopsies met inclusion criteria, and 1,084 were positive for skin cancer. Fifty-four of the positive results were for melanoma. The NNB was 2.86 for all skin malignancies; further breakdown revealed an NNB of 1.91 for nonmelanoma skin cancer and 20.93 for melanoma.
“In short, in order to find one non-melanoma skin cancer takes approximately three biopsies (the other two biopsies are of things that look like cancer, but are benign),” said Meyerle. “For melanoma, more biopsies are needed, as melanoma can look like an abnormal mole.”
Unsurprisingly, the researchers found that the NNB decreased as patient age increased, going from 17.61 for patients under 35 to 1.81 for patients over 65.
The study also revealed that the incidence of melanoma was significantly higher in the study population compared to the general population. (Melanoma typically accounts for about 1 percent of all skin malignancies, but it accounted for nearly 5 percent of diagnosed malignancies in the study.) However, Meyerle says this is likely influenced by selection factors.
“Military personnel who were seen at Walter Reed were referred by their primary care provider, who was concerned. In this way, those who had a suspicious lesion or were at high risk for other reasons were enriched in the study cohort,” he said.
Still, melanoma does have a higher incidence in the military than the population at large, although it’s unclear whether this is due to inherent risk factors of military service (for example, sun exposure). Military servicemembers also generally have good healthcare access, which may increase the likelihood that skin cancer will be detected.
The study also found that members of the U.S. Marine Corps had a slightly lower relative risk for skin malignancy compared to other service branches (Army, Navy, Air Force, and “other,” which included the Coast Guard, Public Health Service and Department of Defense contractors) and enlisted members had a lower relative risk than officers. This correlates with the findings of a large retrospective review of melanoma incidence from 2005 to 2014 that showed incidence of melanoma was lower among the Marine Corps than in the Air Force, Navy or Army and higher among officers than enlisted members. The authors hypothesize that certain career fields limited to officers (such as pilots) could contribute to increased occupational exposure, resulting in increased risk for skin cancer.4
“For non-melanoma skin cancer, the role of UV exposure is significant, and many military service members have high UV exposure during the course of their careers,” said Meyerle. “In addition, the military often selects people who have a history of high sun exposure.”
However, the factors that contribute to melanoma are less clear. Therefore, scientists should focus on which cohorts within the military warrant more aggressive screening for melanoma—such as those with a family history of melanoma, a prior history of nonmelanoma skin cancer or numerous moles—while continuing to ensure that all military personnel have access to robust medical and dermatologic care.
The study authors also caution that using NNB as a metric for dermatologic care should be carefully considered, as the value itself leads to many statistical ambiguities and avenues for bias.
“Patient populations are diverse. If you are taking care of a population that has black or brown skin, you will have very few things that require a biopsy to exclude skin cancer, as skin cancer is generally under-represented in this population,” said Meyerle. “However, if you are taking care of a population with white skin, there will be many more suspicious lesions, thus more biopsies will be required to find the ‘true’ skin cancer. Therefore, generalizing NNB across different subpopulations is problematic, as the metric may not be applicable.”
- Skin Cancer: Incidence Rates. American Academy of Dermatology. https://www.aad.org/media/stats-skin-cancer
- Yong J, Raiciulescu S, Coffman, M, Meyerle, J. Skin Malignancy in the Military: A Number Needed to Biopsy Analysis. Military Medicine. Published February 18, 2021. DOI: 10.1093/milmed/usab039
- Final Recommendation Statement: Skin Cancer Screening. U.S. Preventive Services Task Force. Published July 26, 2016. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/skin-cancer-screening
- Lee T, Williams VF, Clark L. Incident diagnoses of cancers in the active component and cancer-related deaths in the active and reserve components, U.S. Armed Forces, 2005-2014. Medical Surveillance Monthly Report. Published July 2016.
