Analysis of the melanoma epidemic, both apparent and real - Data from the 1973 through 1994 surveillance, epidemiology, and end results program registry

Background: The incidence of melanoma has been increasing faster than that of any other cancer in the United States. It is unclear whether the increas e is related to increased surveillance or other changes in the disease. Objective: To examine changes in melanoma rates by several measures of seve rity of disease and to review the ways in which increased surveillance may cause lead-time bias through early detection or length bias through detecti on of clinically insignificant lesions as a basis for interpreting these ch anging rates. Design: Population-based incidence rates for 1973 through 1994. Setting: United States Surveillance, Epidemiology, and End Results Program tumor registries. Patients: A total of 47 638 cases of melanoma among white patients aged 20 years and older. Main Outcome Measures: Relative incidence rates for melanoma by stage, and tumor thickness adjusted for age and sex. Results: Localized-stage melanoma increased, but no significant change for distant-stage melanomas was seen. Among those diagnosed from 1988 through 1 994, there were 22%, 26%, and 31% increases for tumor thickness less than 1 .0 mm, between 1.0 and 3.0 mm, and 3.0 mm or greater, respectively. The 2-y ear mortality rates also increased over time. Conclusions: While these data show large increases in early disease (locali zed stage, thin tumors), they also suggest some increase in advanced diseas e (thick tumors, 2-year mortality). This indicates that the increasing inci dence rates of melanoma are not solely caused by increased early detection and diagnosis of clinically insignificant melanomas, but may also represent a true increase in cancer rates.