Tibolone and breast cancer

Abstract

Tibolone is a relatively new drug for postmenopausal women, which is structurally related to 19-nortestosterone derivatives and exhibits weak oestrogenic, progestogenic and androgenic activities. The effect of tibolone on breast tissue is still obscure. In vitro studies have shown conflicting results regarding the effects of tibolone on breast cells. On the other hand, although epidemiological studies show an increase in the risk of breast cancer among women treated with tibolone, accumulation of data obtained from radiological studies presents promising results. However, the safety of tibolone with regard to breast tissue needs to be investigated further, especially through well-designed, large-scale, randomised-controlled trials.

Efeitos da tibolona sobre o parênquima mamário: estudo experimental

“…Outro ponto é que pode ter ocorrido viés de seleção, uma vez que o tempo médio decorrido entre a inclusão no estudo e o diagnóstico de câncer de mama foi de 1,2 anos, e de 1,7 anos entre a inclusão no estudo e o falecimento por câncer de mama. Tais resultados são pouco plausíveis do ponto de vista biológico 32 . Segundo a curva de Gompertz, uma célula tumoral leva 180 dias para se dividir, de forma que para se dividir 30 vezes levaria 10 anos, atingindo então 1 cm 33 .…”

“…Segundo a curva de Gompertz, uma célula tumoral leva 180 dias para se dividir, de forma que para se dividir 30 vezes levaria 10 anos, atingindo então 1 cm 33 . Dessa forma, seria improvável afirmar uma correlação direta entre a terapia com tibolona e o risco aumentado de câncer de mama em um período de tempo tão curto como o observado no MWS 32,33 .…”

The management of menopausal symptoms in women following treatment for cancer at a specialist menopause service

“…Similarly, the use of tibolone remains divided in these patients, despite previous evidence suggesting its risk being comparable to estrogen only HRT (Erel 2006). The LIBERATE (Livial Intervention following Breast cancer: Efficacy, Recurrence, And Tolerability Endpoints) trial was designed to assess the use of Tibolone in breast cancer survivors (Kenemans 2009) but again closed prematurely due to an increased risk of recurrence.…”

Inhibitors of 17β-Hydroxysteroid Dehydrogenase Type 1

“…(11)) is a 19-nortestosterone derivative with a tissue-specific mode of action. Tibolone and its metabolites are affect the activity of different enzymes involved in estrogen metabolism [47,70,71]. The 3hydroxy and 3 -hydroxy metabolites (56a, 56b) have affinity for estrogen receptors and 4 -isomer (56c) for androgen receptor.…”