AAD: Skin Cancer Risk Low, but Mortality High for People of Color

SAN DIEGO, July 28 -- Skin cancer -- long thought to be of major concern primarily to Caucasians -- is a danger to those with darker skin as well, investigators reported here.

"Physicians and patients don't think skin cancer occurs in people with skin of color," said Hugh Gloster, M.D., of the University of Cincinnati, speaking in an interview after his oral presentation at the American Academy of Dermatology's summer meeting.

And, in fact, skin cancer is rare in darker-skinned populations, he said. The rates in Caucasians are about 70 times higher than among blacks, for instance. "But when it does occur, it tends to be more deadly" than in Caucasians, Dr. Gloster said.

One reason for that, he said, is that neither patients nor doctors are on the lookout for skin cancer in populations with darker skin, so that cancer tends to be diagnosed later, when it is less treatable. But another key reason, he said, is that two of the major forms of skin cancer -- melanoma and squamous cell carcinoma -- occur in different parts of the body than they do in Caucasians.

In Caucasians, those cancers tend to appear in areas that have been exposed to the sun. But in people with darker skin, Dr. Gloster said, melanomas tend to appear on areas of the body that are not typically exposed to sun, such as the palms of the hands and soles of the feet, while squamous cell carcinomas tend to appear on the legs, often in old scar tissue.

The result, he said, is higher morbidity and mortality:

• Melanoma represents between 1% and 8% of all skin cancers in blacks, and is 16 times more common among Caucasians, but the five-year survival rate is between 20% and 30% lower in blacks.
• Squamous cell carcinoma is the most common skin cancer among blacks -- about 30% of the total -- but the mortality is between 15% and 30%, compared with less than 1% among Caucasians.

The location of melanoma and squamous cell carcinoma in non-sun exposed areas suggests that UV radiation doesn't play a major role in the development of these cancers among darker-skinned populations, he said.

In all races, however, basal cell carcinoma is related to sun exposure, and there is no difference in morbidity and mortality, Dr. Gloster said. However, because of the link with sunlight, people with darker skin are much less likely to get the disease: Only about 1.8% of basal cell carcinomas occur in blacks, for example, and the disease is about 19 times more common in Caucasians.

In a retrospective review, some of which was presented here, Dr. Gloster and colleagues found that incidence for all three cancer types have increased between 5% and 8% among Caucasians in the U.S., over the past 50 years, but have remained relatively constant among blacks.

Nonetheless, the non-Caucasian population of the U.S. is projected to be 50% of the total by 2050, and doctors will need to be on the lookout for skin cancers, he said.

"I talk to physicians all the time who don't think that blacks can get skin cancer," Dr. Gloster said. "We need to have more awareness."