Letrozole and checking estrogen levels

I too would like to test the real times effectiveness of AI . I just started my 5th month of AI … in my case … Anastrozole. Thank you for posing the question.

I was on Anastrozole and I posed this exact question to my Ex-Oncologist. Found another, but he could not answer either. Prior to my surgery or even prior to staring AI, no test was performed that would give a baseline of my estrogen level. When I inquired with my oncologist ‘how do you k ie this AI is working, as you do not have a baseline comparison. He said ‘we just take it for granted’. 😱. That is not the right answer from a doctor from my pint of view. He flippantly said he could do an estrogen test. All the results of that test said <10. 🤷‍♀️ He said that’s good. My thinking is maybe it was already less than 10. I went to a Women’s clinics and paid for an estrogen test of estradiol and another I can’t remember, but due to the fact there are standard test comparisons could not be done.
You would Think the Estrogen level would be an important indicator since that is what the AI is ‘suppose’ to be working on. As of this date I’ve not received good info to my satisfaction.

I asked before I started therapy to do level and then when I started having side effects to do a level. What I was told the current commercial tests available are not accurate enough. Only research labs can answer and look at levels below 10. I find this really unsatisfactory. Because of this o e size fits all with drug dosing which does not make sense.

I too inquired about having a baseline estrogen level before starting AI. I was told by oncologist that it isn’t necessary because the AI result they are looking for can’t be measured. AI blocks estradiol from converting to estrogen. But I still don’t understand why this ( baseline /change) cannot be measured.

I did read an article ( if I find it I’ll post) that stated Anastrozole has a half life of 50 hours and further, older women may metabolize meds more slowly. This is something I will try to check on my next appointment with oncologist. I have minor observed side effects but I worry about the unseen effects such as bone mineral density and cholesterol.

I had the same question. My oncologist said they do not do that test. It will determine if you will get AI or not. I have decided if I will take that drug as yet. I already have bone density issues.

With the number of similar questions regarding baseline estrogen levels before starting AIs, it is clear to me that doctors and practitioners are not knowing how the AIs are affecting our levels. Like my Ex Oncologist told me, when asked how they know it’s working when there’s no baseline, ‘We just take it for granted’ NOT the correct answer.
I stopped my Anastrozole April 15 of this year. Made me feel 90 yrs old. I couldn’t even get in or out of car w/o help. Hip pain was bad. Instead of blaming the meds, I bought orthotics, did PT & walked (the best I could) to rule out it was me. It almost 5 months and I’m back to normal, for me. I’m able to be active again. I think at the 6 month mark or 9 months I’ll have the same estrogen test I had that just stated <10. I don’t know what that means but my EX oncologist (who flippantly told me, that was good) It’s the only number I have. 🤷‍♀️ The decision to stop AI was not easy. My hubby and I discussed at length. My quality of life at 69 is important and I’m proactive w/ my health. The decision isn’t for everyone and every cancer situation is different. My oncologist appoint last month went well and she didn’t try snd talk me into continuing w/ med. 🙏🏼 It continues to go well.
Blessings to you all.

We make hard choices to the best of our ability and then we must move on. Blessings to you!

I wish you well and respect your decision. I too have wondered why estrogen levels are not being baselined and monitored with aromatase inhibitors for the same reasons. There are statistics to support the long term AI use however why not integrate monitored estrogen levels with those statistics? This could define a population that may not need to suffer through this. Maybe that has been done. I haven't searched yet. I started on letrozole 3 months ago. I'm medicating my joint pain and stiffness with fair relief from daily ibuprofen, but concerned about long-term regular use of both. I',m 63 and worried about my quality of life as well as osteoporosis. I am looking for a different oncologist and will incorporate this question in my "2nd opinion". I am also seeing a high-risk breast cancer specialist NP for another reason next week. I will discuss it with her and get back to you. I was started on letrozole prior to bilat. mastectomy with 5 tumours and now informed that I cannot get an Oncotype DX test due to my breast tumour tissue needed for this test must not have been exposed to AIs and must be at least 2 mm piece of continuous tissue. The size requirement rules out all 6 biopsy samples I am left being told if I needed any treatment, they will never know so get on with my life. have no sense of prognosis and any potential chemo I may have needed will not be considered. No special monitoring. This is another issue with studies and practice not in sync.

Lextrozole is killing my joints. I am looking for a new oncologist as soon as my Medicare kicks in.