[Tamoxifen flare].

Tamoxifen flare is a relatively seldom occurring phenomenon but it can force to therapeutical consequences. In every case a careful control of patients has to perform. As yet do not exist clear definitions as well as precise explanations of mechanism of action of flare and tamoxifen withdrawal response. These are related to normal metabolism of tamoxifen and can not explain satisfying flare occurrence in a small number of patients only. By reason of clinical experiences in most cases flare can be regard a sign for hormone sensitivity of the tumor and its following regression. But again do not exist clear explanations for this fact.