Changing from Anastrazole to Letrozole - has anyone done this - any problems?

Hello Cloudier,  I went on a google search and found older articles that said that Letrozole was more effective than Anastrazole but wanted something more current.  Found an article that was published in 2017 that said Aromatase inhibition with Anastrazole was 97.1 and for letrozole more than  99.1.  I have attached the link as there are other factors too.  Here is the link.https://www.futuremedicine.com/doi/10.2217/fon-2017-0228

Thanks and I have been on Anastrazole since May as my tumors were 100% estrogen and progesterone positive.  One breast early stage 1 and the other breast DCIS .  I am going to ask my medical oncologist about it.  I am tolerating Anastrazole well.

Barbara

Hi Barbara. Thank you for taking the time to check things out and attach a link. Like you, I’ve been had a dig around of the research papers. I’ve come across one (which I can’t find now) that studied Anastrazole being taken for ten years (I’m on them for ten) and in that paper (2022 or 2021) it found that Anastrazole was very much worth taking for ten years. The benefits were substantial if you fitted into a particular category of tumour type, size, nodes affected etc, but not as good if you didn’t fit into that tumour type etc.
Like you, I have found research papers on Anastrazole v Letrozole. As you say, there is a slight difference between them. But one thing these papers mention also, is that it’s important to consider patient tolerance of the AI being prescribed. Can they tolerate it for the full 5 or 10 years. I am tolerating Anastrazole well, and my fear is that I might not tolerate Letrozole as well (certainly the list of side effects on the Letrozole  leaflet is much, much longer than the Anastrazole one. 
I have to say, that this change was driven by me, after reading the papers. The oncologist that I asked (not my normal one but a Consultant research oncologist) said that there wasn’t really a difference between them. They both did a good job. She prescribed both, but she did say that if the tumour was very high hormone receptive, then L was marginally more effective. IF you can tolerate it for ten years. My oncologist agreed to change me, but now Im wondering if I have been a bit silly. 
I’ve seen posts from people changing from L to A because of the side effects, but I can’t remember any the other way round. But I am very likely wrong. Thank you again, much appreciated. 

Ps. You mention that you are both Oestrogen and progesterone positive. Well so am I. That paper that I mentioned above also mentioned O and P positive patients versus patients who were Oestrogen positive only. I’ll see if I can back track and find it for you. 

You can always change back if the side affects are worse x

Thanks Rozalia. That is very true. They did say that. 
Hopeful Barb. Here is that paper. https://oncology.medicinematters.com/esmo-2022/breast-cancer/data-trial-extended-adjuvant-anastrozole-ebc/23518768. I don’t know if it is a reputable one or not. I think they don’t like us googling because there is a lot of incorrect stuff out there.