Why are dosages for estrogen suppression drugs one-size-fits-all?

First cancer was in 2004. The joint pain improved in most joints after five hellish years on Arimidex, except for the wrists. Thay have never improved. It took me two years to go from 160-140, so I was never able to get back down to 130. I am 5'5". Then the cancer came back in the other breast in 2021,during covid. I refused to take Arimidex again b/c I told my oncologist I would never spend five years of my life living in that hell again. I never slept more than 2 hours at a time for five years b/c of the pain. I was single and working full time through it all.
She said they have other options now and suggested I take the monthly infusions(2) of Faslodex and promised that "there are no side effects" . I wanted to believe that and did well on them for the first three years, then it was just like being back on the Arimidex only worse b/c now I had severe muscle spasms all night long, sometimes in both legs at the same time. It got to the point where I couldn't walk and my wrists were so sore I couldn't open or lift anything. My eyes got so dry, the lids felt like they were sticking to my eyeballs and I had to see a specialist and the only drug I could take was $1,500/month for the drops, and b/c the drug is excreted by the kidneys and made my urine smell like rotting motor oil for eight days after the infusions, I had full blown UTIs. Sometimes I would get nauseated and begin to vomit for no apparent reason. After 4.5 years, I said I have had enough. No more. The weight is back up to 158, and again, no matter what I do, it won't go away. Now I am in PT to try and get back my ability to walk and go up and down stairs without holding on to the banister and dragging myself. My wrists are worse than ever and my PT wants me to start OT to see if I can avoid having to have surgery on both hands. I think I have nerve damage to the left thumb b/c it trembles uncontrollably. I am sorry I ever took these drugs and if it comes back a third time, I will refuse them all.
A herbalist recommended the selenium and said that it degrades estrogen, which is what the drugs above are supposed to do.

@wews I'm interested that you had a bilateral mastectomy with stage 1a ILC & no lymph node involvement. My case was similar, I was diagnosed last August at age 72, also stage 1a ILC & had lumpectomy with clean margins. 5 days of radiation. Due to my reluctance to take an estrogen blocker, my oncologist agreed to prescribe a half-dose (10mg) of Tamoxifen, to help my thin bones & hopefully avoid usual side effects. I've only taken it since Jan. 1st, but yes, so far, so good! I honestly pretty much forget that I even take it each night, along with my statin. Each of our stories is unique & helpful. I wish you & everyone many healthy years ahead!

@jmab I know I went to both both although my lymph nodes showed clear in my mri they didn’t know for sure that would be the case when they biopsied them after surgery. I felt since I had invasive lobular cancer it was best to get rid of both breasts because I read ILC likes to return and sometimes to the other breasts. My oncologist said tamoxifen was a choice but it can raise chances of ovarian cancer which requires regular checks. It so happens I have a dear friend who developed ovarian cancer while on the drug and had to have a hysterectomy. So I shied away from it. I do like your oncologists approach though and I suppose I could do tomaxifin like you and just get frequent check ups. We all have these tough choices. I so appreciate your insight. It certainly is an alternative for me!

@wews well, it's certainly true that ILC likes to spread! I'm sure you'll do your own research, but for the record (& I'm certainly no expert), Tamoxifen raises the risk of uterine cancer in older women like us. While it blocks estrogen receptors in the breast, it does the opposite in the uterus (for some reason?!) & increases estrogen in the uterus. Which can cause issues. The first symptom of something wrong would be bleeding. And some women do regular ultrasounds to check the uterus but I don't think it's considered standard of care. The risk is very small, but it does exist. I'm pretty sure there is no increased risk of ovarian cancer but again, definitely do your own research & don't take my word for it! The other risk for older women is blood clots. Again, small risk but not zero. I related to what you said about wondering about the women like us who refuse to take hormone blockers. I had visions of my hair falling out & all sorts of terrible things! So, the fact that I'm doing fine has been a huge relief. It's definitely an interesting journey that many of us find ourselves on, isn't it? Again, sending best wishes! We're all in this together!

@amusingmother
Thanks for the heads up on this!! I'm on exemestane now, and haven't started herceptain yet due an upcoming surgery. So I will be aware of this. So far, minor night sweats, but knock on wood, nothing more. I am taking Propel a water supplement that has electrolytes in it seems to be keeping the side effects to a minimum. Perhaps the electrolytes might be the game changed for the exemestane. But, get your hesitation on that one! The second part is definitely wilders than chemo. But, that was a journey I don't want to go on again!!