Limited-Duration Prevalence represents the proportion of people alive on a certain day who had a diagnosis of the disease within the past x years (e.g. x = 5, 10 or 20 years). Registries of shorter duration, less than 40 or 50 years of data collection, can only estimate limited-duration prevalence.
Limited-duration prevalence can be further classified into periods from year of diagnosis. Thus, the 20-years prevalence can be further classified into the prevalence of those diagnosed in the last 0 to < 5 years, 5 to < 10 years, 10 to < 15 years, and 15 to < 20 years.
NCI's SEER Program has information on cancer cases since 1973; however, prevalence calculations usually begin in 1975 due to a different number of registries participating in years 1973-1974. Thus a maximum of 35-year prevalence can be estimated from SEER cases diagnosed from 1975 through 2009.
Limited-duration prevalence statistics can be calculated using the SEER*Stat software.