When to Switch from Zoladex + Tam to Aromatase Inhibitors?

At my first appt (at nearly 51) my onc said I should take Zoladex + Tamoxifen for two years then switch to aromatase inhibitors, presumably on the assumption that I would by then be post-menopausal. Does anyone know how they check the menopause status before switching drugs, or if they actually check? If I’m taking Zol + Tam then a blood test won’t be much use, so are they just assuming that by a certain age I’ll be post-menopause?
Any info on this would be gratefully received.
Sarah x

Hi Sarah
I’m not sure how they’d check either, especially as you would be on drugs that would, presumably, confuse the issue? After my chemo (age 46) it was assumed that I would be now menopausal but a blood test only showed perimenopausal/menopausal. This was done before I re-started any hormone treatment so did give a clear reading. As Tamoxifen hadn’t worked for me I was keen (to say the least!) to go onto Aromatase Inhibitors so opted for ovary ablation as I didn’t want to keep having Zoladex. I understand that the ‘official’ classification of post menopausal (naturally rather than medical intervention) is not having a period for 2 years so, again, I’m not sure how your status could be confirmed.

Hi Sarah

You definitely need a blood test before you switch. I’m 47 and was put on tamoxifen and the surgeon wanted to switch me to letrozole as a blood test last year showed me as postmenopausal.

Fortunately I spoke to my gynaecologist about this and he said you can come out of a chemo menopause up to about 5 years after treatment. He advised more regular blood tests to check. In March around 15 months after finishing treatment I came back out of menopause. Thank goodness I hadn’t switched!

The blood test is a simple hormone profile which I have done at my GP practice. It tests for follicle stimulating hormone, luteinising hormone and oestrogen - the measurements of these will indicate menopause or not.

It may help to know when your mum and grandmother had their menopause. My mum’s wasn’t until she was about 58 and the gynaecologist we often follow that pattern (although it’s just a guide of course).

I don’t know what influence zoladex will have. I haven’t been given that I’ve been told by my GP, Oncologist and surgeon that it isn’t the normal treatment. Can I ask why you’re on that please?
Elinda x

Hi Nicky & Elinda, thanks for your replies.

Yes, that’s my problem, how will a blood test show anything useful if I’m taking two hormone surpressing drugs? I suppose they might ask me to stop taking them for a while to do the blood test but that doesn’t seem a good idea.

My menopausal status was unknown when I was diagnosed with BC, a blood test showed I was peri-menopausal, but I’d had a Mirena coil for years so no clues due to periods or lack of. My mum had a hysterectomy in her early 40s so no clues there either.

Re Elinda’s question on Zoladex. My onc put me on Tamoxifen plus Zoladex because I turned down chemo. He had offered chemo because the Adjuvant Online numbers showed I was in a grey area where chemo wasn’t considered necessary, but could offer some benefit. Zol + Tam offers more protection than just Tam. NICE Guidelines tell them only to offer it if the patient has turned down chemo - they don’t mention it before then, which I think is unfair. I suspect cost comes into it.

I wasn’t impressed by the first onc so asked for a 2nd opinion and she said she wouldn’t even have offered chemo and wouldn’t have bothered with Zoladex either, that Tamoxifen on its own would be OK. But if I wanted the “belt and braces” approach, take both. So that’s what I’m doing.

The first onc viewed my BC as a 3cm grade 2 (with clear nodes) whereas onc No 2 said she thought it was really a large grade 1 with a bit of DCIS next to it, hence the difference in approach.

But I still don’t know how they will know when it’s time for me to switch to AIs.

Sarah x

Sarah - thank you for explaining why you’re on zoladex, that makes sense.

Tamoxifen doesn’t actually suppress hormones. I’m no expert but the way it was explained to me is that tamoxifen would get to any potential cancer cells before oestrogen would, so in effect it’s blocking rather than suppressing. Therefore you can have a blood test taking tamoxifen.
I’ve had all my blood tests whilst taking tamoxifen and have markedly different results in the December and the March results.

Zoladex is different as it switches off the ovaries and puts you into a temporary menopause (as I understand it).

If you were going to switch to an AI, then it might be worth coming off zoladex, keep on tamoxifen and then have a blood test? From what I understand you don’t want to switch to an AI if you aren’t postmenopausal as it won’t offer enough protection.

Incidentally you can take tamoxifen even if you’re postmenopausal. My Onc is planning to keep me on it for 5 years regardless of whether I’m postmenopausal or not becuase of joint pain. My Onc said that the difference in survival rates is very marginally better if you switch to an AI when post menopausal.

I think the best thing would be to either speak to the helpline or to your Oncologist and get some expert advice. You need to be reassured that whatever you do will be the best possible thing for you. Elinda x

Oncologists seem to be saying different things at the moment. When I first started tamoxifen (Oct 2007) I was told I would switch to an AI after two or three years. When I had my three year check up last year, I saw a different oncologist as my original one had retired. She told me the protocol had now changed, and if you were pre menopausal before dx you should stay on tamoxifen for the whole five years. This is for the reason Elinda found - it is not possible to predict whose menopause will reverse, and if your menopause reverses, you need to be on tamoxifen as AIs will not work

Hello, i am on Tamoxifen,just come off 2 years Zoladex.My consultant is going to take me off the Tamoxifen in a few months so she can do blood tests then put me back on it.This is how she can then decide if i have to have further treatment (i am 51) i had no menopause symptoms befor the Zoladex.

Hi All and thanks for the extra info.

I phoned the BCC helpline and they said it varies from one hospital to another and one consultant to another as to how long you stay on which drugs and when you switch from one to another. They said the blood test (FSH) should still work whilst on the Tam + Zol but it’s a rather unreliable test anyway. Apparently most people go on Tam for a minimum two years to start with, then some stay on it longer, some switch. And as RoadRunner says, the latest thinking also changes.

No clear cut answers, as is so often the case with this bl***y disease!

I’m due to see my consultant in a few weeks, I’ll ask her for more info.

Sarah x

Thanks for letting us know. Be interested to know what your consultant says too. Elinda x

Hi All

Its a bloody minfield isn’t it.!! I am due to come off Tamoxifen after 5 years next month. I have had blood tests but they can’t decide if I am peri or post menopausal! My oestrogen is very low but FSH is still peri apparently.

I had no periods for 3 years after chemo but in the last 2 years I have bleeds about every three months but they think this is caused by Tamoxifen not ovarian function returning but they are not sure!!! I have had 2 endometrial biopsies which were both fine.

I REALLY dont want to go on an AI next month for 3 more years which is what onc suggested ( depending on blood tests).

Apparently I have a 1.4% chance of a recurrence in the next 5 years if I stop Tamoxifen and have nothing and a 1% chance if I go on an AI. I am thinking its not worth the side effects for a .4% increase!! I want to stay on Tamoxifen for a few more years but onc is adamant I have to stop after 5 years - I am not sure why?

It’s all a bloody never ending nightmare!!

Love to all


I don’t think you get any more benefit after five years.

I’ve seen some studies which say you can get some benefit with up to 10 years of various Tamoxifen and AI combinations. Confused? You bet!
Sarah x

I am also having conversations with onc. I was told I would go on tomoxafen for 2 years and then switch to Arimidex. My blood test was inconclusive.

However, after chemo, the onc told me I would go straight to Arimidex as I was post menopausal. I have only been free of monthlys for 1 year and have not had any symptoms of menopause.

Saw onc team yesterday and they are not sure why I am on Arimidex and will check records and come back to me!!

How do I know I am on the right treatment?


I’ve checked back over the letters copied to me by my oncologist and he said I will be on Tamoxifen + Zoladex for “up to 2 years”, after which I should have two blood tests a couple of months apart to check that I’m really menopausal. At that point I will be 53 so I should be menopausal by then. As long as the result is inconclusive I guess I’ll stay on the Tam + Zol.

Janvis - from what I’ve read it’s important not to go onto AIs unless you really are menopausal because if you aren’t, the AIs can stimulate your ovaries to produce more oestrogen - not what you want.

Sarah x