TUESDAY, June 22 (HealthDay News) -- The incidence rate (IR) for cutaneous appendageal carcinoma (CAC) in the United States is low and varies by sex/ethnic group, but it has been increasing, possibly partly due to increased ultraviolet exposure and improvements in diagnosis, according to research published in the June issue of the Archives of Dermatology.
Patrick W. Blake, of the National Institutes of Health in Bethesda, Md., and colleagues analyzed data from the Surveillance, Epidemiology, and End Results Program, 1978 to 2005, to determine incidence patterns of CAC in the United States.
The researchers found the IR for CAC low (adjusted for age, 5.1 per one million person-years), but significantly higher among men than women, at 6.3 and 4.2 per million person-years, respectively. Rates were significantly lower among Hispanic whites, blacks, and Asian/Pacific Islanders (3.7, 3.5, and 2.5, respectively) than among non-Hispanic whites (5.7). Rates rose 100-fold with age, from 0.37 among people in their 20s to 37.3 among people 80 or older. The most common category was apocrine-eccrine carcinoma. Between 1978 to 1982 and 2002 to 2005, the overall CAC IR rose 150 percent, from 2.0 to 5.0, while the apocrine-eccrine carcinoma IR rose from 1.0 to 2.7 and the sebaceous carcinoma IR rose from 0.6 to 1.9.
"CACs are rare tumors with IRs that vary by sex and racial/ethnic group. CAC IRs are increasing in the United States, especially for sebaceous carcinoma, perhaps related to improved recognition and classification, but factors such as ultraviolet exposure and immunosuppression may also play a role," the authors write.