letrozole(femara) more effective than anastrazoloe(arimidex) in lowering estradiol,

[Lani]

estrone sulfate

Study has not yet correlated that with risk of recurrence

ABSTRACT: Letrozole Suppresses Plasma Estradiol and Estrone Sulphate More Completely Than Anastrozole in Postmenopausal Women With Breast Cancer
[Journal of Clinical Oncology]
Purpose: To compare the effects of anastrozole and letrozole on plasma estradiol (E2) and estrone sulfate (E1S) levels.
Patients and Methods: Fifty-four postmenopausal women with estrogen receptor-positive breast cancer receiving aromatase inhibitors (AIs) as part of their adjuvant therapy were randomly assigned to receive either 3 months of anastrozole (1 mg) followed by 3 months of letrozole (2.5 mg), both given orally once daily, or 3 months of the opposite sequence. Blood was taken at the same time and the same day of the week from each patient, before and after 3 months of each drug, and plasma levels of E2 and E1S were determined using highly sensitive radioimmunoassays.
Results: There were 27 patients in each group. The mean age of the patients was 63 years (range, 49 to 83 years). Baseline E2 levels ranged from 3 pmol/L to 91 pmol/L with a mean of 25.7pmol/L. Only one of 54 (2%) patients had an E2 value ≥ 3 pmol/L after receiving letrozole, versus 20 of 54 (37%) patients after receiving anastrozole (P < .001). Extrapolation revealed a mean E2 level after anastrozole treatment of 2.71 pmol/L (range, 2.38 to 3.08 pmol/L). Following letrozole, it was 1.56 pmol/L (range, 1.37 to 1.78 pmol/L). Mean residual E2 was 10.1% for anastrozole and 5.9% for letrozole. Residual E1S levels were 4.6% for anastrozole and 2.0% for letrozole (P = .001).
Conclusion: Letrozole reduces plasma E2 and E1S levels to a significantly greater extent than anastrozole in postmenopausal women taking AIs as part of their adjuvant therapy for hormone receptor-positive breast cancer.

[CLTann]

From this article, there are indeed major differences between Femara and Arimidex. Why are the doctors keeping on to tell their patients that these two medicines are identical. Some of them even refused to switch.

[Jean]

Hi Ann,
I believe we will begin to hear more on AI's as the new data starts to
filter in. I remember my onc. told me that the two were similiar in the way
they worked, but that does not preclude there would be variables between the two products.

Regards,
jean

[Soccermom]

Thanks for this Lani,
My best friend has just recurred 10 years after her original dx! She has mets to hip pelvis and lungs is ER/PR+ and is now on Femara. I will pass this on to her

Thanks again,Marcia

[Margerie]

I just had some blood work done. My estradiol was 32 and my FSH was 59.12.

I am 41, had an ooph and started Arimidex 2 years ago. Shouldn't my estradiol be lower? I will bring it up to my onc. But I am wondering if any one of you switched from Armidex to Femara to lower your estradiol level and if so, did it? I was er+/pr+.

[Jean]

Hi Margerie,
I just had blood test yesterday to check my estroen levels and when I get them back will share them with you. I did switch from Arimidex to Femara but for the reasons of joint pain.

I do know that your levels can go up and down.
In menopause, the general range may be 10-20 pg/ml or 40-70 pmol/L, depending on the testing method.

Hope this helps?
Regards,
jean

[Gerri]

Hi Margerie,

I had my levels tested in April to see if I was in menopause yet. Two of the three tests came back that I was, my FSH was in the normal range. My onc consulted an endocrinologist at the cancer center and she recommended getting another test - the Anti Mullerian Hormone test. It confirmed that I am post-menopausal. Maybe you can request that test be done. I switched from Tamoxifen to Femara a week ago - so far so good.

All my best,

[harrie]

Is it routine for any of you to have your estrogen levels checked? If so, what is the reason for this? Is it to see if the AI is working?
Just wondering. No one has ordered labs to have my levels checked.

[Jean]

Hi Maryann,
I do not believe it to be routine.
But I wanted to have mine checked since
I have not had my estrogen levels checked since
starting on an AI treatment plan.

Just want to make sure the levels are low.
Have been on Femara for over a year now.

jean

[harrie]

Hi Jean, boy you are sure up late tonight! It is only 8:50 over here!

[harrie]

Jean, how are your joints doing now that you have been on Femara for a yr? Have you tried glucosamine?
maryanne