Has anyone had the Tamoxifen CYP2D6 test?

I’ve just found out that the AI that I’ve been taking (Femara) for 4 months isn’t working, so I will be switching to Tamoxifen. Having had one hormonal therapy fail, I’m rather anxious to find out if I am a Tamoxifen metaboliser or not. I know the CYP2D6 genetic test is available now in the UK - has anyone had this test? Would be grateful for any information. Thanks.

finty x

Hi Finty

I’ve not had the test but am very interested to see responses.

How do they know that the Femara isn’t working? (Thank goodness you’ve been having your flaxseed.)

Elinda x

You may have already seen this indepth article on testing - makes for interesting reading:


Thanks Elinda - very interesting article, it’s not as straight forward as I had assumed. I know the Femara isn’t working because I asked for some scans to check if it was - one of the advantages of being a private patient it getting scans pretty much whenever you want them. I had very good results with Avastin with no progression at all. But after 4 months on Femara I have a new bone lesion - a very small one that wasn’t spotted on the CT but the bone scan picked up some activity, and when they then looked back on the CT they could see a tiny hole. So will hope to have better luck with Tamoxifen.

finty x

I am very sorry to hear that.

I knew that the testing wasn’t straightforward but didn’t know why until I read the article. I should think in your case, if it’s okay to have another scan that would be a better and far more valid indicator. Elinda xx

Thanks Elinda x

i’ve had the test done.i had to pay to get it done privately,but my nhs consultant arranged it after i asked for it.i had a blood test in the hospital then the blood was taken by courier to the clinic that does the testing.the results were sent to my consultant.it cost about £450.it showed that i am able to metabolise tamoxefin .if I remember there’s a scale of about 4 levels and all except the lowest level can metabolise to an effective level.once i had the test the results can with notes explaining it in detail.I had it done about 9 months ago.I had to request the test as my consultant didn’t mention it.

hi, i really dont understand what this test is for. could someone explain very simply please

Cluck thanks so much for your reply - I missed it until today. Was your consultant aware of the test and did he/she think it is an accurate predictor of Tamoxifen working?

Lincs lady - my simplistic understanding of the issue is that Tamoxifen is only effective if it is metabolised by the body into another form. There are a group of people (I think it’s about 20%) that have a genetic mutation that prevents them making this metabolite - and this is what the test does - finds out if you have that gene mutation. However, if you read Elinda’s link above it suggests the issue is more complicated.


I had this test in Germany last year. It showed that Tamoxifen works for me. But at the San Antonio conference in December 2010 there were reports on studies which showed that the test is not predictive:



Umm, that was the same information elinda posted. But she did not say what it was exactly and I did not click on her link. Sorry about that.


This is a summary from the Dr Susan Love research foundation of what the research means re testing - please note it’s important to read right through to the end.