US Prostate Cancer Rates Dropping for White Men; Stabilizing for African-American Men

After increasing sharply from 1989 through 1992, US prostate cancerincidence rates dropped by 16% for white men and nearly stabilizedfor African-American men (2% increase) in the latest period availablefor analysis, 1992 to 1993. These findings, based on the NationalCancer Institute's Surveillance, Epidemiology, and End Results(SEER) cancer registry information and US Census population estimates,are reported in the November 20th issue of the Journal of theNational Cancer Institute.

In this brief communication to the Journal, researcher Ray M.Merrill, phd, mph, and colleagues at the NCI explain that muchof the dramatic increase in the age-adjusted prostate cancer incidencerates noted in the 1989 to 1992 period (61% among whites and 65%among African-Americans) has been attributed to the widespreaduse of prostate-specific antigen (PSA) for screening and detectionof prostate cancer. This recent analysis of the SEER data, compiledfrom the 9 standard population-based tumor registries that togethercover approximately 10% of the US population (with over-samplingof certain minority populations), indicates that prostate cancerincidence rates began to fall earlier in the 1992 to 1993 periodin some geographic areas (eg, Seattle-Puget Sound) and that ratescontinue to vary by region (eg, lowest in Connecticut and Iowa;highest in metropolitan Detroit, Utah, and Seattle). (Despitethese differences, the decline in incidence occurred in each SEERarea.)

In addition, incidence rate changes varied by 10-year age intervaland by race. For all SEER areas combined, declining rates wereobserved in the three older age groups for whites and the twoolder age groups for African-Americans. These findings are consistentwith incidence trends in screened populations, say the authors.Since screening tends to identify cases earlier, incidence ratesin younger age groups rise and rates in older age groups drop.Specifically, the percent changes in rates for white males from1992 through 1993 were: +4% for ages 50 to 59 years, -9% for ages60 to 69 years, -20% for ages 70 to 79 years, and -29% for ages80 years and older. For African-American men, the percent changesin rates for the same time period were: +25% for ages 50 to 59years, +15% for ages 60 to 69 years, -8% for ages 70 to 79 years,and -17% for ages 80 and older.

Merrill and his colleagues suggest that additional research isneeded to determine why prostate cancer incidence rates beganto decline in 1992 and 1993. The decline may, they say, reflectreduced use of PSA for screening and detection due to unresolvedquestions about its value, given the morbidity and mortality associatedwith treatment for early-stage prostate cancer. Further inquiryinto the basis of the observed prostate cancer incidence ratechanges may also provide additional insight into the natural historyof this disease and the performance characteristics of PSA screeningtests, say the researchers.