Survival prospects after screen-detection of prostate cancer.

Abstract

To ascertain more realistic survival values for screen-detected prostate cancer than those in current use which are derived from conventionally presenting, usually symptomatic, populations. Survival data for conventionally detected cases were derived from the Surveillance, Epidemiology and End Results database for men diagnosed in the years 1983-1988. The incidence of screen-detected prostate cancer by age and grade was taken from published data. For a cohort of men, initially 55 years old, screen-detected cases were estimated to outnumber by 2-3-fold, depending on age, those detected by conventional means. By assuming various survival characteristics for the screen-detected cases the mean lead time was estimated to be 9 years. Because screen-detected cases usually have clinically localized disease they are commonly advised on survival times derived from conventionally detected cases. Applying these survival times over-predicts the number of deaths by factors of at least 3.4, 1.9 and 1.5 at 65, 75 and 85 years old, respectively. Screening detects prostate cancer a mean of 9 years before clinical presentation. The prognosis of screen-detected prostate cancer is considerably better than that of conventionally presenting localized disease. The advice given to patients with early prostate cancer should take account of this.