In a research work carried out by researchers at CIC bioGUNE it was found that oestrogen can cut the risk of breast cancer.
Their work shows that oestrogen is capable of reducing the number of breast cancer stem cells, which may explain the lower aggression of the tumor and, as a consequence, the possibility of a better prognosis.
The research combined the use of human samples and laboratory cell lines.
Oestrogen is a hormone which is not without its complexity; on the one hand it is essential for the normal development and functioning of the breast and, on the other, this same hormone induces the proliferation of cancer cells once the breast tumour has appeared, i.e. oestrogen is also a risk factor in breast cancer.
However, nothing or little has been known until now about the effect of oestrogen on the tumour-initiating cells.
It had also been proposed that the number of cancerous stem cells is correlated with the aggressiveness of the tumour: The greater the percentage of breast cancer stem cells, the greater the aggressiveness and the worse, thereby, its prognosis.
"To our surprise, what we have seen is that oestrogen reduces the proportion of breast stem cells which means a mechanism for explaining this better prognosis observed with tumours that express the oestrogen receptor. That is, those tumours expressing the oestrogen receptor are less aggressive, better differentiated and thus have a better prognosis", explained Mar a Vivanco, leader of the research team.
The project was published in Breast Cancer Research and Treatment.