Prostate carcinoma incidence and patient mortality: the effects of screening and early detection

Screening for and the aggressive treatment of prostate carcinoma are controversial, but they are nevertheless being practiced in the U.S. Current clinical studies of the effectiveness of screening will take years to complete. Meanwhile, screening for prostate carcinoma is already having an effect on society.

National and regional trends in prostate carcinoma incidence and data on patient mortality and survival from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute are described in this article. SEER is a population-based cancer data base comprised of nine discrete areas. Fundamental principles of screening are used in this article to explain the impact that prostate carcinoma screening has had in the U.S.

According to the data in the SEER registries, overall prostate carcinoma incidence rates increased at a far greater pace than prostate carcinoma mortality rates during the period 1973-1994. During that period, there was a shift in stage at diagnosis characterized by an increase in local and regional disease, and a decline in distant disease at diagnosis. Overall 5-year survival rates for prostate carcinoma patients also increased. The increase in incidence rates, the shift in stage at diagnosis, and the increase in survival rates are all evidence of increasing early detection. However, these changes are consistent with lead-time bias, length bias, a decline in mortality, and all three could have occurred. In the geographic SEER registries, the prostate carcinoma incidence rates vary markedly. These variations in incidence rates are due to regional variations in practice patterns and screening efforts. On the other hand, the SEER registries have comparable mortality rates. This is evidence of both lead-time bias and length bias.

Substantial regional variations in incidence were found, but regional mortality rates were similar. This is evidence that screening and early detection efforts are resulting in the diagnosis of prostate carcinoma in some men who do not need therapy; thus, prostate carcinoma screening can lead to unnecessary treatment for such men. Furthermore, epidemiologic data do not demonstrate that screening is decreasing mortality. The benefits of screening and early detection, although theoretically possible, are yet unproven, whereas the risks and harms of screening and resultant treatment are definite.