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Skin Cancer in African-Americans

Skin Cancer in African-Americans

S kin cancers are less frequently observed in African-American patients. Most likely, this decreased frequency is due to the photoprotection conferred by the melanin in darkly pigmented skin. But despite the lower risk to this patient population, African-American patients who develop skin cancers are faced with an increased morbidity and mortality, which is often a result of delayed diagnosis in this patient population. In this column, I’ll take a closer look at the types of skin cancers that most often affect this patient population and discuss typical presentations of lesions in African-American patients. Overall Distribution One study of 215 patients compared the distribution of all skin cancers in Caucasian and Hispanic patients to African-American patients. This study demonstrated that head and neck involvement is less common in African-Americans, comprising 44% of all skin cancers, compared to 76% in the control group.1 Of the head and neck skin cancers, the anatomic distribution was similar between the two groups with the most common locations on the scalp and nasal skin. The ratio of basal cell carcinoma (BCC) to squamous cell carcinoma (SCC) on the head and neck was also comparable between the two groups with BCC being more common (4:1). In photoprotected skin, the ratio of SCC to BCC differed greatly between the two groups. SCC was more frequent than BCC in African-American patients with a ratio of 1:8.5 in non-sun exposed regions. In contrast, the ratio of SCC to BCC in the control group in photoprotected skin was equal (1:1). The authors concluded that although head and neck skin cancer is less common in African-American patients, the distribution and presentation of head and neck skin cancers is similar in all skin types. In photoprotected skin, however, SCC is more common than BCC in African-American patients.1 Basal Cell Carcinoma Basal cell carcinoma is the most common skin cancer in North America. BCC most commonly presents on the sun-exposed regions of fair-skinned individuals. Although infrequent, BCC has been reported in African-American patients.2 A series of 14 African-American patients with BCC revealed that most lesions were asymptomatic. Most patients presented with hyperpigmented, translucent nodules on the head and neck. In this series, only one patient had lesions located in a non-sun exposed region. The authors concluded that BCC in African-American patients, as in Caucasian patients, is related to ultraviolet light exposure. In addition, no clinical or histologic differences in BCC were reported in either Caucasian or African-American patients.3 BCC has also been reported in African-American patients after X-ray treatment for tinea capitis. A large study followed 2,224 X-ray treated children for up to 50 years to determine the BCC incidence in these patients. Of these patients, 25% were African- American. The X-ray treated group was compared to a control group of children who had tinea capitis but were treated with only topical medications. Of the African-American patients, only three BCCs were observed. All of these patients were in the irradiated group. The risk of BCC was much higher in the irradiated Caucasian patients. This finding emphasizes the importance of UV radiation as a co-factor in developing BCC in these patients. Although both African-American and Caucasian patients in the irradiated group were more likely to develop BCC, the greater pigmentation in African-American patients’ skin offered some protection from co-factors, such as ultraviolet radiation. Consequently, the overall risk of BCC in the African-American patients who underwent irradiation was lower than Caucasian patients who received this treatment.4 Nevoid basal cell carcinoma syndrome (NBCCS) is another condition that has been described in African-American patients. Interestingly, the expression of basal cell carcinomas is diminished in patients with dark skin and NBCCS.5,6 Thus, despite a genetic defect contributing to BCC formation, the innate photoprotection in darker -skinned patients appears to blunt the expression of multiple BCC in these patients.5 Squamous Cell Carcinoma SCC is the most common skin cancer in African-Americans.7 As mentioned previously, SCC is more frequently seen in non-sun exposed regions than BCC in African-American patients. One study examined the distribution of SCC in African-Americans and found that 16 of 35 patients diagnosed with SCC had lesions on the legs that exhibited atypical features. All these patients were elderly African-American women. The authors concluded that SCC is not rare in elderly African-American women.7 Other factors that have been associated with SCC in African Americans include albinism, burn scars, chronic inflammation, chronic discoid lupus erythematosus and epidermodysplasia verruciformis.8,9 African-American patients with SCC tend to present with more advanced disease and have increased mortality.8 Melanoma The annual incidence of melanoma in African-American patients ranges from 0.5 to 1.1 per 100,000 compared to 2 to 17 per 100,000 in Caucasian patients.10 Malignant melanomas are divided into four subtypes including nodular, superficial spreading, lentigo maligna and acral lentiginous melanoma. Acral lentiginous melanoma is the most common subtype of melanoma in African-American patients.11 Melanoma can also be categorized by its location on the body. There have been suggestions that plantar melanoma is more common in African-Americans than in Caucasians. In fact, the incidence of plantar melanoma is equal among the races.12 However, in African-American patients with melanoma, the plantar and palmar surfaces are the most frequent location.13 Nonacral sites for melanoma are less common in African-American patients, making the overall incidence of melanoma in African-American patients lower than in Caucasian patients. Although the incidence of melanoma is lower in African-American patients, melanoma is, in fact, a more lethal disease in this population. The California Cancer registry reported a 5-year survival rate for African-American patients of 70% compared to a survival rate of 87% for Caucasian patients.14 Another recent study examined melanoma survival rates at Washington Hospital Center. This study found a 5-year survival rate in African- Americans of 58.8%, compared to 84.8% in Caucasian patients.15 African-American patients were less likely to present with in situ stage I disease than Caucasian patients (39.3% vs. 60.4%). Furthermore, African-Americans were more likely to present with stage III/IV disease than Caucasians (32.1% vs. 12.7%).15 Delayed diagnosis and treatment in African-American patients may explain the large disparity in survival rates observed between these two groups. Other Cutaneous Neoplasms Cutaneous T-cell lymphoma is seen in all races; however, the hypopigmented variant appears to be more common in darker-skinned individuals. In one series of seven patients, all patients had skin types IV or V.16 Patients with hypopigmented mycosis fungoides tended to have delayed diagnoses ranging from 7 months to 10 years from disease onset to histological diagnosis.17 In younger patients, hypopigmented mycosis fungoides is frequently misdiagnosed as pityriasis alba.17 One should consider hypopigmented mycosis fungoides in any darkly pigmented patient who has diffuse persistent hypopigmented patches. Many other cutaneous neoplasms have been reported in African-American patients. They include sebaceous carcinoma, trichilemmal carcinoma and microcystic adnexal carcinoma.18,19,20 Due to the rarity of these cutaneous neoplasms, their exact incidence in African- Americans isn’t known. Points to Remember When Treating this Special Population Skin cancer in African-American patients has many unique features to consider. Ultraviolet radiation, as in Caucasian patients, appears to play a role in BCC formation in African- Americans. In African-American patients, BCC is not associated with an increased morbidity. However, an emphasis on sun protection should not be ignored in these patients. In contrast, SCC in African-Americans presents in later stages and in some studies is associated with increased morbidity and mortality. Early diagnosis and intervention is essential in African-American patients with SCC. Finally, there’s a need for increased awareness of melanoma in African-American patients. Unfortunately, this disease is often diagnosed in later stages and has a higher mortality rate in this patient population. Increased patient and physician education on pigmented lesions of the hands and feet is essential in addressing this serious issue.

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