Oestrogen Reduces Aggression In Breast Cancer

NattyOnFrostyLake

  "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 Ms María Vivanco, leader of the research team.

http://www.medicalnewstoday.com/articles/216450.php

Member_of_the_Club

OK, estrogen positive cancers tend to be less aggressive, not that giving someone estrogen will make their cancer less aggressive.  And the reason these cancers are less aggressive is because they are more like typical breast cells, so the receptors are a sign that the cells haven't mutated as much as er negative bc.