Here is some Research I came across...

My understanding of how Tamoxifen works is that it does not block the production of estrogen at all. It binds with estrogen therefore preventing that estrogen from being able to bind with any cancer cells. I guess it would therefore follow that the higher your levels of estrogen the more chance that Tamoxifen will not be able to bind with all of it and those rotten cancer cells might have more chance of getting to it first or instead.

 I know that when I was on Tamoxifen my estrogen levels were checked regularly by my oncologist and when they got a bit high at the 18month mark (high enough for my periods to restart) then it was recommended that I have my ovaries removed. I then swapped to an aromatase inhibitor (Femara) which is what this research is saying might be the thing that tumors can get around by beginning to produce their own aromatase. Good that they are looking into this further! So much research going on which is a good thing.

Well that research just sends shivers right through me knowing that my cancer was as a result of too much oestrogen.  My recent blood tests everything is normal but that still doesn't stop the shivers!!

Hi Mel, hope you are doing OK. I saw that too and it seems to be a particular issue with the aromatase inhibitors but it is interesting that your friend on Tamoxifen is getting high readings. It's certainly a concerning finding that some of these tumours are evolving to produce their own type of oestrogen  :/

Hi Melinda, I hope you’re recovering well from surgery. This is good to know! I always get copies of my bloodwork and go through it. Rita xo