Is Tamoxifen working? How do we know?



Can anyone tell me if there is a way we can know for sure if tamoxifen is working and protecting us or how we would know if it is not working ? 

Hi Shablah


Your best bet is to ask your breastcare team or oncologist to direct you to the research (Google is way too unreliable) or better still, show yu and talk you through it. I assume oncologists have access to data that’s presented in visual form, showing the statistical difference any particular treatment can make - but related to your specific cancer. Certainly mine did when he needed to talk me into chemotherapy and it worked.


I can understand your wanting to know. Is the misery worth it? The last time I saw my latest oncologist, she wanted to take me off anastrozole because of the side effects. This was maybe 10 minutes after I’d read an article in my reliable newspaper about research showing that anastrozole is by far the most effective HT for post-menopausal women. The statistics cited were convincing. I decided to soldier on but I’m sometimes in agony and really wonder how much difference it’s going to make - I’m seeing her Friday and I know she’ll suggest coming off it again. Aaaargh. Decisions.


Basically, we don’t KNOW HT works because nothing is definite. We are being given a better chance with HT but there are still no guarantees. It will work for one woman but not for another. Did you, like me, assume that once the big treatments were over, that was it??


Best of luck x


Hi Shablah,


Oestrogen positive breast cancers effectively feed off oestrogen. The Tamoxifen acts as an oestrogen blocker in the breast tissue, providing some protection against the oestrogen your body produces. 


You can check how taking Tamoxifen statistically increases survival over a 5, 10 and 15 year period for someone of your age, size of lump, number of nodes involved (if any), and whether oestrogen positive etc on NHS predict online. Not everyone feels comfortable looking at such figures, so it is a personal choice.  Alternatively you could ask your oncologist to show or talk you through the statistics. They are averages, and so other personal health factors need to be considered too.


Recently there have been some studies done on taking Tamoxifen for 10 years rather than 5, and the results indicate that taking Tamoxifen for 10 years actually provides some degree of protection for a number of years beyond that. I asked my oncologist about further reading on this, and again, not for everyone but the ATLAS study shows the statistics for the extended period. Reliable article in the Lancet, 


From a personal perspective, I certainly wasn’t relishing the thought of taking it…did get some side affects, including bad hot flashes. Found sage capsules helped for about 18 months, then they got worse again before eventually easing off a tad.


Three years after initial diagnosis I had a secondary scare…turned out to be old fractured ribs…but during that scare period I realised how if I hadn’t have taken the Tamo, I would have felt like I’d increased my chances of a recurrence and been kicking myself! Thankfully I didn’t have to kick myself since I’d taken Tamo and then thankfully got the good news of old fractured ribs - hurrah! Not secondaries. 


So roll on to the 5 year Tamo point, planning a free-the-Tamo-one party in my mind…and then the onc said, oh, research now indicates benefits of taking it for 10 years. So I have now shifted my free the Tamo one party to the 10 year point!


Basically bc can be sneaky. Bc cells can hide out dormant in your bones and then become active years later. Tamoxifen helps reduce the chances of any local recurrence and any hiding dormant cells getting up to no good! So, while there are no guarantees, and it is a personal decision, please do consider taking it for the above reasons and speak to your oncologist if you have doubts or unanswered questions. The “what if” scenario is also a good personal guide…none of us want to look back and wish we’d done something which may have made a difference long term…


Really hope the above helps you decide what is right for you,


Seabreeze (5 years Tamo and counting!)       




My first diagnosis was in 2011 when 43 yo. My period stopped permanently after 2nd cycle of chemo. My onco told me to take tamoxifen for 10 years. In the first couple years, I had 1 time acid reflux (usually happened when I was sleeping). It was resolved not sure bcoz of the prescription medication or bcoz I changed to take tamoxifen from before bed to morning. I had 4 times UTI (never happened before and touch wood, not after up to now)  and quite strange, all happened  in about 6 months gap. I had 1 time uncontrolled pee for about few hours and this time I didn’t go to see any doctors. Basically,  I think I am quite lucky, the SE is very minimal, no pain, no hot flushes. After 3-4 years on Taxmoxifen, my hospital discharged me. Since then, I started to take the pills irregularly (avg 2-3 times a week).

My SBC was dxed in Oct 18. 3 months before dx,  I completely stopped tamoxifen myself and eventually started high dose bee propolis. At my 1st appointment with onco, I told her all these and she agreed bee propolis, not taking tamo. regularly all might contributed to my SBC. In the 2nd appointment, my onco reminded me to stop taking Tamoxifen, she said it was not working. I asked “but… my hair was thinned (for years) when I was taking the tamoxifen (my hair started to grow thicker after I stopped tamoxifen)”. She said different cells responded differently. Though no evidence, I regretted so much for stopping myself. My onco comforted me saying don’t blame yourself. It just happened and was not linked to it. However, when I took the estrogen test before started Letrozole, my estrogen level was HIGH.