GnRH-Antagonisten – eine neue Therapieoption beim fortgeschrittenen Prostatakarzinom

Zusammenfassung

Die medikamentöse Kastration mit LHRH-Agonisten (luteinisierendes Hormon Releasing Hormon) gilt als Therapie der Wahl für Patienten mit fortgeschrittenem Prostatakarzinom. LHRH-Agonisten unterdrücken die Testosteronsynthese und senken die Serum-Testosteron-Spiegel auf Kastrationsniveau. Der Vorteil gegenüber der Orchiektomie ist, dass die medikamentöse Kastration reversibel ist. Ein Nachteil der LHRH-Agonisten ist, dass es nach Therapiebeginn initial zu einem vorüber­gehenden Anstieg des Serum-Testosteron-Wertes kommt. Dieser sog. Testosteron-Surge erhöht nicht nur das Risiko des unerwünsch­ten Tumorwachstums, sondern kann auch dazu ­führen, dass krankheitsbedingte Beschwerden zunehmen (Flare-Phänomen). Nicht ausgeschlossen ist eine Verschlechterung der Gesamtüber­lebenszeit betroffener Patienten. Mit den GnRH-Antagonisten, auch GnRH-Blocker genannt, steht eine neue endokrine Therapieoption zur Ver­fügung. Gegenüber den LHRH-Agonisten haben die Antagonisten den Vorteil, dass sie keinen Testosteron-Surge induzieren. Der Testosteronspiegel im Serum sinkt innerhalb weniger Tage nach Therapiebeginn deutlich und anhaltend ab – ähnlich, wie dies von der Orchiektomie bekannt ist.

Abstract

At present medical castration employing luteinis­ing hormone releasing hormone (LHRH) agonists is the standard of care for patients with advanced prostate cancer. LHRH agonists suppress the synthesis of testosterone to a castration level. In contrast to surgical castration, medical castration is reversible. However LHRH agonists induce an initial increase of the testosterone level. This so-called testosterone surge leads to tumour growth and increases the disease-specific complaints, known as flare phenomena. It may be possible that the overall survival of these patients is deteriorated. In contrast, gonado­trophin releasing hormone (GnRH) antagonists do not induce a testosterone surge and the level of testosterone decreases as rapidly as that known from a surgical castration.

Schlüsselwörter

Prostatakarzinom - LHRH-Agonisten - GnRH-Antagonisten - GnRH-Blocker - Testosteron-Surge - Flare-Phänomen

Key words

prostate cancer - LHRH agonists - GnRH antagonists - GnRH-blocker - testosterone surge - flare phenomena

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