RESUMO
BACKGROUND: Active surveillance (AS) represents an expectant treatment strategy for clinically localized prostate cancer (PCa) with low-risk features. OBJECTIVE: The actual management as well as the pros and cons of AS were evaluated. METHODS: A systematic review of the recent literature was performed using the Medline databases. CONCLUSIONS: Since a substantial number of men die with rather than from PCa, there is a considerable role for AS in carefully selected men. AS may also represent a strategy to reduce the burden of overtreatment rooted in intensified PSA testing. Facing the imprecision of risk stratification based on transrectal ultrasound-guided biopsy, accurate clinical staging represents a major medical challenge. Counseling and care require empathy as well as a profound understanding of the biology and the natural history of PCa.
Assuntos
Detecção Precoce de Câncer/métodos , Neoplasias da Próstata/diagnóstico , Progressão da Doença , Humanos , Biópsia Guiada por Imagem , Masculino , Programas de Rastreamento/métodos , Oncologia/normas , Próstata/patologia , Antígeno Prostático Específico/sangue , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/patologia , Neoplasias da Próstata/psicologia , Fatores de Risco , UltrassonografiaRESUMO
This paper focus on the quest for mechanisms that are able to create tolerance and an activation threshold in the extrinsic coagulation cascade. We propose that the interplay of coagulation inhibitor and blood flow creates threshold behavior. First we test this hypothesis in a minimal, four dimensional model. This model can be analysed by means of time scale analysis. We find indeed that only the interplay of blood flow and inhibition together are able to produce threshold behavior. The mechanism relays on a combination of raw substance supply and wash-out effect by the blood flow and a stabilization of the resting state by the inhibition. We use the insight into this minimal model to interpret the simulation results of a large model. Here, we find that the initiating steps (TF that produces together with fVII(a) factor Xa) does not exhibit threshold behavior, but the overall system does. Hence, the threshold behavior appears via the feedback loop (in that fIIa produces indirectly fXa that in turn produces fIIa again) inhibited by ATIII and blood flow.
