Dark-skinned patients still at risk for skin ca

OB/GYN News,  June 1, 2005  by Michele G. Sullivan

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NEW ORLEANS -- Melanoma and other skin cancers in blacks and Hispanics are likely to be discovered at a more advanced stage and are associated with significantly poorer survival rates, researchers said at the annual meeting of the American Academy of Dermatology.

Blacks and Hispanics--and their primary care physicians--may believe that darker skin protects against these cancers, said Susan Taylor, M.D. As a result, these patients don't perform frequent skin self-exams, aren't taught the warning signs of skin cancers, and don't see pigmented lesions as a concern.

These problems, coupled with the fact that skin cancers often occur in atypical or sun-protected areas, contribute to their poorer prognosis.

Physicians "must develop a high index of suspicion for melanoma in the black population and fully evaluate any suspected lesion," said Dr. Taylor, who is the director of the Skin of Color Center at St. Luke's-Roosevelt Hospital Center, New York.

Additionally, she said, health care providers should tell dark-skinned patients that they are at risk for melanoma, must wear sunscreen, and should perform monthly self-exams of their skin.

Malignant melanoma is about 10 times more common in whites than in blacks. Dark skin transmits only about 7.4% of ultraviolet B and 17.5% of ultraviolet A, while white skin transmits more than 55% of UVB and 29% of UVA, said Rebat Halder, M.D., of Howard University, Washington.

"As a result of this additional filtering, black skin has a natural SPF of about 13.4," he added.

But this natural protection isn't enough, noted Shasa Hu, M.D., of the University of Miami. Dr. Hu presented the results of a population-based study of skin cancer registries in six states: California, Texas, Florida, New Jersey, Illinois, and New York.

Her results showed that increasing ultraviolet index and decreasing latitude were both significantly associated with invasive melanoma in blacks and Hispanics, especially among women.

"The geographic variance in the occurrence of melanoma was similar to what we see in white populations," Dr. Hu said. Dark-skinned patients will benefit just as much as light-skinned ones from education about sun safety, sunscreens, and skin cancer identification.

A chart review of 649 melanoma patients at Washington Hospital Center found that while 90% of melanomas in whites occurred on sun-exposed skin, only 33% of those in blacks occurred on sun-exposed skin. The most common site of melanoma for black patients was the foot. Almost 40% of melanomas on blacks occurred there, vs 2.4% of the melanomas on whites, Dr. Taylor said.

This same study found significant differences in stage and survival rates between the groups (J. Am. Acad. Dermatol. 2004;50:21-4). Stage I occurred in 60% of whites and 39% of blacks. Stage III or IV occurred in 33% of blacks but only 13% of whites. Five-year survival rates were about 59% for blacks and 85% for whites.

Other skin cancers have similar characteristics when they occur in blacks, Dr. Rebat said.

Squamous cell carcinoma (SCC) is the most frequently seen skin cancer in blacks, but 65% of cases occur on sunprotected skin, frequently in the anus (15% of SCC overall, and 25% of SCC in black females). SCC also is associated with a later diagnosis and a more aggressive form of the disease.

"SCC on covered skin has a greater potential for metastasis," Dr. Halder said at the meeting.

SCC is more common in blacks with light or albino skin and on skin that has been damaged by burns, chronic ulcers or inflammation, chemical exposure, or lupus. In blacks, SCC is sometimes confused with psoriasis, eczema, infection, or trauma.

BY MICHELE G. SULLIVAN

Mid-Atlantic Bureau

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