Hormone concentrations of dominant follicles in the TALES randomized controlled trial comparing letrozole with
Ange Wang1, Joseph M Letourneau2, Flor Juarez-Hernandez3
1Division of Reproductive Endocrinology and Infertility, University of California, San Francisco, 499 Illinois Street 6th Floor, San Francisco, CA, 94158, USA. ange.wang@ucsf.edu.
Background:
In this secondary analysis of the TAmoxifen or Letrozole in Estrogen Sensitive tumors (TALES) trial, we aimed to investigate if concurrent administration of letrozole vs. tamoxifen vs. no added treatment affects hormonal composition and size of stimulated ovarian follicles.
Methods:
TALES is a randomized controlled trial of IVF stimulation for estrogen receptor (ER)-positive breast cancer patients stimulated with gonadotropins and administered concurrent tamoxifen 20 mg or letrozole 5 mg. We analyzed estradiol (E2), testosterone (T), progesterone (P4), follicle stimulating hormone (FSH), luteinizing hormone (LH), and anti-Mullerian hormone (AMH). We used ANOVA/Kruskal-Wallis, logistic, and linear regression models to examine differences in follicular hormone levels, size, and mature oocyte yield between trial arm.
Results:
We included data from total 246 follicles (94 letrozole, 82 tamoxifen, and 70 control) from 123 unique participants. E2 was lower (letrozole 187.4, tamoxifen 1026.0, control 821.5 ng/mL, p < 0.01) and T was higher (letrozole 2489, tamoxifen 571, and control 504 ng/mL, p < 0.03) in the letrozole group compared to tamoxifen and control groups, while other hormone levels and follicle size were similar across groups. There were no significant differences in hormone concentrations within the follicle between tamoxifen and control arms. On multivariate logistic regression, there was no significant association of mature oocyte yield by follicle size, hormone levels, or trial arm.
Conclusions:
Concurrent administration of letrozole with gonadotropins affects follicular E2 and T concentrations compared to tamoxifen/control. Tamoxifen was not associated with any differences in hormone concentrations within the follicle. Mature oocyte yield was similar across groups.
Related Concept Videos
01:30Hormonal Control of the Ovarian Cycle
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle. At puberty, GnRH secretion increases in both frequency and...
01:22Hormonal Regulation of the Menstrual Cycle
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH...
01:27Ovarian Cycle
01:22Target Cell Response to Hormones
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...
01:24Gonadal and Placental Hormones
In males, testosterone is the primary gonadal androgen. It plays a central role in the maturation of male reproductive organs — the penis and testes. Additionally, testosterone is instrumental in the development of secondary sexual characteristics — a deep voice as well as facial and pubic hair...
01:20Folliculogenesis