Cutaneous cancers in skin of colour
Frequency and presentation of common skin cancers in different populations (1,200 words, 6 minutes, 10 seconds)
Skin cancer is often diagnosed later in patients with skin of colour because of differences in presentation and a lack of public awareness, said Dr. Andrew F. Alexis at the 7th Annual Skin Spectrum Summit on Nov. 4. As a result of delayed diagnosis, he said, patient prognosis is frequently worse in these populations.
“Most will recognize the late great Jamaican reggae superstar Bob Marley, but fewer may realize that he was a victim of malignant melanoma. He died at the young age of 36, secondary to a sublingual melanoma on his right big toe that metastasized to multiple distant sites,” he said. “Decades after the death of Bob Marley, a lot of the issues surrounding skin cancers and skin of colour remain. There is low public awareness [of this disease].”
Dr. Alexis is the vice-chair for diversity and inclusion for the department of dermatology and a dermatologist at the Center for Diverse Skin Complexions at Weill Cornell Medicine in New York City.
When looking at the epidemiology and clinical presentation of skin cancers, Dr. Alexis said there are notable differences among ethnic populations.
He noted individuals in these populations are also more likely to be diagnosed with melanoma when the cancer is in an advanced stage and have increased lesion thickness and ulceration. These factors contribute to a poor prognosis and worse five- and 10-year survival outcomes.
He noted that the most common skin cancers among Black and South Asian populations—in order of most to least frequent—are squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and melanoma.
SCC: Most commonly seen in the lower extremities in skin of colour. UV exposure is not as significant a risk factor in these populations. SCCs often occur in association with chronic ulcerative and inflammatory processes, and these SCCs have higher morbidity.
BCC: Approximately 50% of BCCs diagnosed in dark-skinned populations are pigmented. Physicians should take notice of lesions that are changing or bleed easily, even in the context of multiple other benign pigmented lesions.
Melanoma: Frequently has a worse prognosis in patients with skin of colour, partially because the location differs. The foot or lower extremities are the most common locations for malignant melanoma in non-White populations. It is critical to include the soles, between the toes and the toenails in screenings. Clinical evaluation of nail discolouration is necessary to distinguish melanoma in this area from benign melanonychia, which is common in darker-skinned patients. Acral lentiginous melanoma is the subtype most commonly seen in this population.
Bottom Line: It is crucial to understand the variations and distribution of skin cancers across patient populations and the differences in clinical presentation in different skin types. Specific care should be taken in cancer screening in patients with darker skin. Even though some cancers are less prevalent in populations of colour, they often have a worse prognosis attributed to delays in detection. Increasing public awareness of these cancers in dark-skinned populations is essential, as is performing thorough screenings that include the palms, soles, nail beds and mucous membranes.
From the literature on skin cancer in darker skin types
Fitzpatrick phototype disparities in the identification of cutaneous malignancies by Google Reverse Image
Noting that the general public frequently searches for health information online, the authors of this research letter aimed to evaluate the accuracy of Google Reverse Image (GRI) search in identifying cutaneous neoplasms in different skin types.
Prior research by the same group had shown GRI having moderate diagnostic frequency but limited accuracy for cutaneous neoplasms in general.
The authors write that their new findings support the hypothesis that GRI performs more poorly for dermatologic queries in skin of colour. They suggest that this discrepancy may reflect insufficient availability of images depicting Fitzpatrick skin types IV to VI in GRI’s database, leading to GRI's classification algorithm misinterpretation of features unique to this group.
Ulcerated amelanotic melanoma of the ear in an 11-year-old with Fitzpatrick VI skin type: A case report
This case report describes a rare case of an ulcerated amelanotic melanoma in a pediatric patient with very dark skin. The authors of the paper note that while risk factors for this type of cancer are similar in adults and pediatric cases, the presentation in pediatric patients is often distinct from how it appears in adults.
The patient in this report was treated successfully with wide local excision and a one-year regimen of nivolumab. This treatment was well tolerated.
Characteristics of publicly available skin cancer image datasets: A systematic review
This systematic review aimed to identify and evaluate all publicly available skin image datasets used for skin cancer diagnosis and found a shortage of images of skin of colour. The authors explored the characteristics, data access requirements, and associated image metadata found in 21 open-access datasets, 17 open access atlases, eight regulated access datasets and three regulated access atlases. Among their findings, the authors noted that subject ethnicity data were available for 1,415 images (1.3%), and Fitzpatrick skin type data for 2,236 (2.1%). There was limited and variable reporting of characteristics and metadata among datasets, with substantial under-representation of darker skin types.
The authors note their findings show that the existing image sets have limited applicability to real-life clinical settings and do not fully represent all. This determines how accurately results of searches of these image sets can be generalized. They suggest that quality standards for characteristics and metadata reporting for skin image datasets are needed.
HSD17B7 gene in self-renewal and oncogenicity of keratinocytes from Black versus White populations
The authors of this research say their findings show that primary keratinocytes (HKCs) from Black African (Black) versus White Caucasian (White) individuals have, on average, higher oncogenic and self-renewal potential. They also identify a gene, HSD17B7, as the top-ranked differentially expressed gene in HKCs and head/neck squamous cell carcinomas (SCCs) from individuals of Black African versus Caucasian ancestries. Modulating this gene, they note, can influence HKC and SCC proliferation and oncogenicity, as well as other cellular behaviours. They write that their findings point to a targetable determinant of cancer susceptibility among different human populations. These findings may be helpful for the prevention and management of the disease.
VIDEO: Melanoma & Skin of Colour
At the intersection of skin and society
The six-part Strong and Free podcast, which tells stories from the earliest Black settlers to recently arrived Canadians, is available through The Canadian Encyclopedia’s website.
This podcast is a creation of Historica Canada, a Canadian organization dedicated to enhancing awareness of the country’s history and citizenship.
Topics covered by the podcast include:
The West Indian Domestic Scheme, a program in the mid-20th century that encouraged young women from English-speaking Caribbean countries to come to Canada as domestic workers.
NHL hockey great Herb Carnegie.
Marie-Josèphe Angélique, an enslaved Black woman alleged to have deliberately started a fire that levelled Montreal’s merchant quarter in the 1730s.
Mary Ann Shadd, the first Black woman to publish a newspaper in North America.
John Ware, a Black man born into enslavement, who went on to become a successful rancher and renowned cowboy, eventually settling near Calgary.
The Haitian Diaspora that developed in Quebec in the 1960s and ’70s as Haitians fled the dictatorship of Francois Duvalier.
All the episodes, as well as transcripts, can be found at the link below.
This Week
Jan. 25 is IV Nurse Day in the US
Jan. 26 is Bell Let’s Talk Day in Canada
Something to think about in the week ahead…
Next Week
Dr. Joel Claveau on the presentation in skin of colour of a range of inflammatory skin conditions, including lichen planus and rarer conditions such as ashy dermatosis, sarcoidosis and lupus.