Melanoma is rare in Black patients, but soles of feet are hot spots, study shows
February 27, 2024
Melanoma, an aggressive skin cancer, is often associated with sun exposure and a history of sunburns. As a result, most melanoma prevention campaigns have focused on sun protection and the use of sunscreen.
Patients with skin of color often want to know whether this advice applies to them: Do I still need to wear sunscreen if I have dark skin? As a Black person, what are my risk factors for melanoma?
These are controversial questions in the field of dermatology. It’s true that melanoma is rare in Black patients. Just 1 in 1,000 Black patients develop melanoma compared to 1 in 33 white patients, and of the thousands of patients listed in our melanoma database treated at UT Southwestern and Parkland Health since 2006, just 48 are Black.
Skin cancer prevention guidelines are built on data from light-skinned patients who make up the majority of patients with melanoma. But not all skin cancers are caused by sun exposure, and not all melanomas originate in sun-exposed areas; some form in the eyes, genitals, or nail beds. In fact, reggae legend Bob Marley, whose life is chronicled in the 2023 movie Bob Marley: One Love, died at 36 from a melanoma that started under a toenail.
Even though melanoma is rarer in this population, Black patients are more at risk for getting diagnosed late and having worse survival outcomes. As a result, there is a critical need to better understand the nature, risk factors, and prevention strategies for melanoma in Black patients. To seek answers, my colleagues and I launched a retrospective clinical study starting with our own patients here at UT Southwestern and Parkland Health.
The findings, which were published in JAMA Dermatology, form the foundation for what we hope will become a much larger, multi-institutional research initiative:
- In the rare cases when a Black patient developed melanoma on their skin, 75% of the cases were classified as acral (on the palms/soles), with most being on the soles of the feet – an area not commonly exposed to the sun and less pigmented.
- Black patients who developed melanoma on other areas of their skin were more likely to be immunosuppressed or have a personal history of other types of cancer.
- The deadliest melanomas in this cohort started in non-sun-exposed places including the foot, sinuses, and genitals.
Our study’s findings are limited because of the small sample size, but this research is just the start of a long-term effort to provide more precise skin cancer prevention strategies for Black patients. We are also pursuing more targeted, effective treatment options for acral and other rare subtypes of melanoma.
Related reading: 5 myths about skin cancer prevention – and some truths
Who is most at risk for skin cancer and melanoma
Dermatologist Stephanie Savory, M.D., discusses skin types that can be more susceptible to ultraviolet rays, and steps you can take to reduce your risk of skin cancer.
Melanoma trends in North Texas
Because melanoma is so rare in Black patients, most of our prior knowledge has come from large national registries that have limited information. For example, these large databases use general terms, such as Lower Extremity, Trunk, or Head to indicate where melanoma was found. While we have known that melanoma in Black patients appeared most often in the lower extremities, the granular details about exact locations such as thigh, calf, or foot were missing.
By leveraging data from our registry of melanoma patients at UT Southwestern and Parkland Health from 2006-2022, we were able to zoom into the details to search for clues, and we identified two striking trends right off the bat.
1. Melanoma in Black patients most commonly starts on the foot.
Of the thousands of patients in our database, just 48 were Black. Among them, 40 had primary cutaneous melanomas, meaning the cancers started in their skin, and 75% of these were acral melanomas of the palms of the hands or soles of the feet, with 28 out of 30 acral melanomas being on the foot. These cancers typically do not respond well to immunotherapy, which is the gold-standard treatment for most other types of melanoma.
We are investigating hypotheses about why acral melanomas were more common in this group:
- The palms and soles may be less protected by melanin than darker areas of skin.
- Palm and sole melanomas may not be caused by sun exposure but by other risk factors yet to be discovered.
2. Personal health history impacts risk for other types of melanoma.
A smaller subset of Black patients in our melanoma database had a non-acral melanoma that started in the skin, such as on the trunk, arm, or head. Among them, 40% were immunosuppressed and 60% had a personal history of another non-skin cancer.
Only three patients had superficial spreading melanoma, a type of melanoma that is typically thought to be sun-induced. All three were immunocompromised and had a personal history of either pancreatic cancer or multiple myeloma, a blood cancer. None of these three patients died from their melanoma.
This study zoomed in on UT Southwestern and Parkland Health but is just beginning to scratch the surface. The next step is to zoom back out and learn whether our findings track with patient experiences outside the Metroplex. We hope to partner with academic medical centers around the country so we can work with a bigger volume of data and provide more precise, effective treatment and prevention strategies for a diverse patient population.
Related reading: Skin Cancer Guide
The ABCDEs of detecting melanoma
When monitoring suspicious skin lesions and moles, dermatologists say to consider factors such as asymmetry, color, jagged borders, and more. Stephanie Savory, M.D., describes the warning signs.
Tips to reduce the risk of melanoma
Notice and act on signs of melanoma. Everyone should keep a close eye out for changing lesions on their skin, but for Black patients, the foot may be the most important place. Look for actively growing or changing moles, sores, or dark patches on the palms of the hands, soles of the feet, between toes and fingers, and under or along the nails. Sometimes melanoma can look like an ulcer or wound that won't heal. Report any changes to your doctor or a dermatologist right away. Don’t wait for it to get worse – at that point, the disease may progress or spread to other parts of the body.
Sun protection is still important. Even if having darker skin provides added protection against melanoma, there are so many tones of skin that dermatologists cannot declare definitively that Black people don’t need to wear sunscreen. While skin cancer is rare in the Black population, patients who get it often are diagnosed at a later stage and have worse outcomes. Larger studies are needed to better understand which Black patients are most at risk and what interventions will best lower that risk.
Be mindful, too, that the sun can damage the skin in many more ways beyond skin cancer, such as contributing to wrinkled or photo-aged skin, broken blood vessels, discoloration and dark patches (melasma), and peeling. Explore 5 burning questions about sun protection.
Consider genetic testing. While none of the Black patients in our cohort had a known family history of melanoma, many patients did have a significant personal and family history of other cancer types. More genetic testing needs to be done to identify cancer genes in families that may predispose people to melanoma. Ongoing research in genetic testing could point to gene variants that may help identify Black patients at risk for melanoma.
Related reading: 3 skin cancer treatments that might stop melanoma in its tracks
In partnership with other research centers, we hope to identify potential drivers of melanoma in Black patients. We are also currently analyzing data from other patient cohorts known to have a lower risk of melanoma. One of our goals is to gather data on a variety of skin types and ethnicities to gain a better understanding of potential trends in risk and outcomes.
We hope our collective research will form the foundation for better strategies to identify patients with skin of color who are most at risk of melanoma and catch it early if it develops.
To talk with a dermatologist about your melanoma risk, call 214-645-8300 or request an appointment online.
