Endometriosis UK

I have breast cancer am on tamoxifen, herceptin, anticoagulant but its causing my endometriosis to flare up badly ? Anyone had this problem?

I am 33 and 1yr into treatment had mastectomy, chemo,immunological medicines, hormones treatment. My endo symtoms eased during chemo as I went into menopause but 5 months post chemo periods are back and hurrendouse heavy, huge clots, painful, bowel pain to just before bowel movement and during so bad it put ke on the floor no matter where I am. I am never allowed hormones again due to my cancer being hormone positive which was my main defense against endo. I have had two surgery s to remove it I was stage 4 endo widespread bowel uretha ect... Its hard dealing with this on top of everthing else thats happening.

11 Replies

I'm sorry I can't be of much help but I wanted to send you a massive cyber hug.

I really think you need expert medical advice.

Best wishes,

Barbara x


Thankyou hun I am just waiting to get back in to see my gyny team who are having to kiase with my oncology team to make sure they dont cause further problems lol oh the joys :) I just feel kinda worried that every period its getting worse and im supposed be on tamoxifen for 10 years ! Like hell can I do 10 years of this but im not stressing just want get as much info I can make more informed choices :)


Would the mirena be an option for you?


Hi my oncologist it adament no coil to be used for me ever because of my cancer.


Although Tamoxifen is an oestrogen antagonist on the ovaries, it's an oestrogen receptor agonist on the uterus. I found that it caused similar issues to those you're describing. I hope your oncologist gets back to you soon regarding suitable alternatives; until then hugs!!!!

1 like

Hi Squeep,

Thank you so much for this. This piece of information has been really helpful to me. A few weeks ago I was diagnosed with ER+ PR+ BC and the doc started talking about using Tamoxifen when I recalled your post. He did know I have endo but when I pointed out the issue he was unaware of the problem!

What did you use in the end?

Hope you're doing ok. x


Hi Sarlouki,

How are you getting on? I've just been diagnosed with breast cancer but hoping to get away with lumpectomy only and no chemotherapy.

Did you sort out the Tamoxifen issue?

How are your endo symptoms? It sounds like you could do with another surgery to clear everything out again but maybe with a different specialist this time. I really hope things have improved for you since you wrote your post.

Sending you hugs. x


Hi brownlow

Sorry for my very late reply i havent been on the site for many months. Also sorry to hear you have been diognosed with breast cancer too. My endo symtoms did just fade away for 7 8 months until this week had very bad endo pain and had routine scan monitor lining of womb picked up an 8cm cyst on my endo ravaged ovary ha ha "it never ends


I do hope your treatment is going well and that your making a good recovery x


Hello there,

Continue to fight and beat this cancer. It is possible. I attached a humurous and inspiring video of a cancer survivor. Stay positive and continue to live on dear.


Hi Sarlouki,

I'm having similar problems but in a reverse order. I'm 33 and I was diagnosed with estrogen+ BC 5 years ago and was on tamoxifen. Now I am diagnosed with endo. After surgery they found out that it's stage 4 and is on bowels also. They took out the ones on ovaries but couldn't do much for the ones on the bowels. Tamoxifen feeds this fire and I can't take it anymore for BC :(

Now my doctors are deciding to put me on menopause (zoladex and aromasin). Not started yet. I'm also thinking of hysterectomy.

How are you doing? Are you on the same medicine?

Hope things better for both of us! Hugs!


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