Changes in Skin Cancer Morbidity Between 1971-72 and 1977-78 1

ABSTRACT-Skin cancer incidence rates for two geographic areas of the United States were analyzed for detection of significant changes in risk over a 6-year period (1971-72 to 1977-78). Changes in rates were examined by cell type, anatomic site, sex, and age. In general risk has increased, but the size of the increase varied by cell type, sex, and anatomic site. Statistically significant increases were limited to tumors of the basal type. The risk of basal cell skin cancer appears to have increased about 18 % or almost 3 % per year. Increases did not depend on age group. Among males the increases were most notable for sites other than face, head, and neck, whereas among females the increases were not associated with site.-JNCI 1982; 69:365-370. In 1971-72 age-adjusted nonmelanoma skin cancer inci-dence rates ranged from 151 to 379 per 100,000 in four geographic areas of the Third National Cancer Survey (1). These incidence rates were far higher than the rate for any other single cancer site and substantially higher than any previously reported skin cancer incidence rates for the United States. In one location, Minneapolis-St. Paul, inci-dence apparently doubled injust 5 years (2). Unfortunately, the meaning of the increase was not clear. The average annual risk of developing the disease could have increased, but the change in incidence rates could have been due to varied or improved case ascertainment methodologies. To provide more data on skin cancer, the National Cancer Institute conducted a skin cancer survey during 1977-78 at several locations in the United States. Two of these locations, Minneapolis-St. Paul and San Francisco-Oakland, were also part of the 1971-72 study and were included in the new survey to provide the data needed to determine if the risk of developing skin cancer is changing. This report contains a summary of the data currently available from these two locations and an analysis of the observed changes in skin cancer incidence rates over the 6-year period by age, sex, anatomic site, and cell type. MATERIALS AND METHODS The data used in this report are from two special skin cancer surveys. The first study, covering a 6-month surve