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

Good morning. You’re right about testing your estrogen levels. I always wonder about that. Is this medicine really working. My breast cancer was high estrogen and I had invasive breast cancer and 2 lymph positive and taking anastrozole for 5-7 years. 58 years old post menopause. Side effects for 3-4 were off the chain until my body adjusted to it. Was diagnosed in Jan of 22. Started anastrozole in Aug of 22. Doing better now. And I still wondering if the drug is doing its job to keep the recurrence down
At the 9 year risk the data shows 17 percent of recurrence with taking anastrozole. I’m questioning that percentage.
Has any one taken this drug and how beneficial is it as years go by. Did lump. And radiation
My oncotype is 20
Ki67 is at 10
Thinking low to medium risk?

I have recently read about a clinical trial (2017) that was to understand the difference between continuous Letrozole treatment after 5 years and intermittant treatment which included a three month break annually after 5 years of treatment. Something to discuss with your doctor.

Abstract
Background: In animal models of breast cancer, resistance to continuous use of letrozole can be reversed by withdrawal and reintroduction of letrozole. We therefore hypothesised that extended intermittent use of adjuvant letrozole would improve breast cancer outcome compared with continuous use of letrozole in postmenopausal women.

We enrolled postmenopausal women of any age with hormone receptor-positive, lymph node-positive, and operable breast cancer for which they had undergone local treatment (surgery with or without radiotherapy) and had completed 4-6 years of adjuvant endocrine therapy

Interpretation: In postmenopausal women with hormone receptor-positive breast cancer, extended use of intermittent letrozole did not improve disease-free survival compared with continuous use of letrozole. An alternative schedule of extended adjuvant endocrine therapy with letrozole, including intermittent administration, might be feasible and the results of the SOLE trial support the safety of temporary treatment breaks in selected patients who might require them.
https://pubmed.ncbi.nlm.nih.gov/29158011/

I am not finding any study that supports this! Many that do support every other day being effective.
It would be helpful if you put a link in your comment(s) that support your statements.

Please see
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4740217/
No difference if take Letrozole every other day or every day.

If you are interested in Metformin read How to starve cancer by Jane McLelland. There are oncologists who prescribe Metformin and other off label drugs that affect various pathways.

Hi
I just finished two surgeries for dcis breast cancer slightly invasive and radiation and my oncologist agreed to put me on 5 mg of tamoxifen I'm 65 and I have osteopenia with a fracture.

Stopping treatment can reverse acquired resistance to letrozole from NIH study.

Using the intra tumoral aromatase xenograft model, we have observed that despite long lasting growth inhibition tumors eventually begin to grow during continued letrozole treatment. In cells isolated from these Long Term Letrozole Treated tumors (LTLT-Ca), ERα levels were decreased whereas signaling proteins in the MAPK cascade were upregulated along with Her-2. In the current study we evaluated the effect of discontinuing the letrozole treatment on the growth of letrozole resistant cells and tumors. The cells formed tumors equally well in the absence or presence of letrozole and had similar growth rates. After treatment was discontinued for six weeks, letrozole was administered again. Marked tumor regression was observed with this second course of letrozole treatment. Similarly in MCF-7Ca xenografts, a six-week break in letrozole treatment prolonged the responsiveness of the tumors to letrozole.

These results indicate that discontinuing treatment can reverse letrozole resistance. This could be a beneficial strategy to prolong responsiveness to AIs for breast cancer patients.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2491346/

Thank you for posting the study. It’s a 2008 study… I should think we need some updated information in this fast moving research world. I think it best to have a whip smart oncologist, who stays up with research, make suggestions regarding AI treatments.

That is a good question. Why don't oncologists test for estrogen and estradiol levels? I have not been seen by one oncologist who tests these levels. When I suggest it, they all refuse.

@thora902 - Excellent question. I wasn’t checked before, during or after for estrogen levels. I took Anastrozole for 2 1/2 yrs. My oncologist said, when asked how he knew the med was working, as they had no baseline of my levels, he said “We take it for granted”. I was So Done with that oncologist! Good luck