Álvaro Páez Borda
Head of Urology Service, Hospital Universitario de Fuenlabrada, Madrid; Associate Professor of Health Sciences, Universidad Rey Juan Carlos; and Chairman of the Spanish branch of the European Randomized Study of Screening for Prostate Cancer
The study-a retrospective study of PSA utilization and prostate cancer (PC) incidence and mortality-addresses the perennial issue of overdiagnosis in the context of PC screening. That undesirable effect-that of overdiagnosis, and consequent overtreatment-historically represents the biggest mortgage for PC screening. And it is the reason why a preventive strategy with a performance no less than that of other similar practices (such as screening for breast cancer or colon cancer) cannot be generalized; a minimum of one in three diagnoses of PC represents overdiagnosis, a much higher proportion than in screening for breast cancer, for example.
The study uses incidence data from the International Agency for Research on Cancer's CI5plus (Cancer Incidence in Five Continents Plus) and the Global Cancer Observatory, and from national and regional cancer registries. Mortality data for the 26 European countries analyzed are from the World Health Organization. The GLOBOCAN databases have also been used to complete the estimation of incidence and mortality. Once the data had been standardized, secular trends were analyzed using the APC (Annual Percent Change) statistic. With regard to the use of PSA, it was only possible to obtain information from 12 countries.
In short, the study shows large cross-national differences in both incidence and mortality from PC. And, once again, it highlights the difference between incidence and mortality.
Considering that some countries included in the study -Spain, among others- do not have a national cancer registry, the incidence data should be treated with caution. Similarly, since the data on PSA use cannot be considered generalizable to all the countries under analysis, the attribution of differences in incidence to variability in PSA use is purely speculative.
Be that as it may, and even if only in broad strokes, the study highlights a critical issue before activating a screening program: overdiagnosis. Given the sterility and undesirable effects of opportunistic screening based on PSA determination, the European Union encourages the cancellation of this type of practice, while promoting the implementation of population-based programs for the early detection of PC; at present, the feasibility of studies based on the use of PSA in combination with magnetic resonance imaging (MRI) is being analyzed, the latter as a means of reducing overdiagnosis. The logistical dimension of such a population-based program can be colossal. Will health systems be able to withstand such an overload?