Cutaneous appendageal carcinomas—tumors of the skin appendages such as hair, nails, sweat glands and mammary glands—are rare but rates appear to be increasing in the United States, according to a report in the June issue of Archives of Dermatology, one of the JAMA/Archives journals.
"Cutaneous appendageal carcinomas are a rare and diverse group of complex neoplasms with diverse differentiation that frequently present a diagnostic challenge," the authors write as background information in the article. Because of their rarity, studies of these cancers have been limited.
Patrick W. Blake, B.S., of the National Cancer Institute, Bethesda, Md., and colleagues examined incidence rates, trends and survival rates of the disease using 16 cancer registries in the Surveillance, Epidemiology and End Results Program from 1978 to 2005. A total of 1,801 patients were identified for incidence analysis, 2,228 for trend analysis and 1,984 for survival analysis.
The age-adjusted incidence rates were 5.1 cases per 1 million people per year, with men more likely to develop one of the cancers than women. Hispanic whites, blacks and Asian/Pacific Islanders all had lower rates of incidence than non-Hispanic whites. The most common type was apocrine-eccrine carcinoma, or cancer of the sweat glands. Incidence rates increased with age, with a 100-fold difference between individuals age 20 to 29 years and those age 80 years and older.
Cutaneous appendageal carcinomas also became more common over time, with a 150-percent increase in incidence between 1978 to 1982 and 2002 to 2005. Rates of sweat gland cancers increased 170 percent and sebaceous carcinomas, cancers of glands in the eyelid, increased 217 percent. Overall, five-year survival rates were 99 percent for localized disease and 43 percent for disease that had spread to another part of the body.
"Cutaneous appendageal carcinoma incidence rates are increasing in the United States, especially for sebaceous carcinoma, perhaps related to improved recognition and classification, but factors such as UV exposure and immunosuppression may also play a role," the authors write. "Further increases in cutaneous appendageal carcinomas over time should prompt new strategies for cancer screening and early intervention of this cancer."