Skip Navigation LinksHome > July/August 2007 - Volume 14 - Issue 4 > Effects of estradiol with oral or intravaginal progesterone...
doi: 10.1097/01.gme.0000247017.41007.80

Effects of estradiol with oral or intravaginal progesterone on risk markers for breast cancer in a postmenopausal monkey model

Wood, Charles E. DVM, PhD1; Sitruk-Ware, Regine L. MD2; Tsong, Yun-Yen PhD2; Register, Thomas C. PhD1; Lees, Cynthia J. DVM, PhD1; Cline, J. Mark DVM, PhD1

Collapse Box


Objective: To evaluate the effects of oral estradiol given with either oral or intravaginal micronized progesterone (P4) on risk biomarkers for breast cancer in a postmenopausal monkey model.

Design: This experiment was a two-way crossover study in which 20 ovariectomized adult female cynomolgus macaques were treated (in equivalent doses for women) with oral estradiol (1 mg/d) + oral micronized P4 (200 mg/d) or intravaginal P4 delivered by Silastic rings (6- to 10-mg/d release rate). Hormone treatments lasted 2 months and were separated by a 1-month washout period. The primary outcome measure was breast epithelial proliferation.

Results: Serum P4 concentrations were significantly greater in subjects receiving oral P4 (10.9 ng/mL) compared with intravaginal P4 (3.8 ng/mL) at 2 to 3 hours after oral dosing (P < 0.0001) but not at 24 to 28 hours after oral dosing (2.9 ng/mL for oral P4 vs 3.2 ng/mL for intravaginal P4 at 2 months, P = 0.19). Serum estradiol concentrations were significantly lower after oral P4 than after intravaginal P4 (P < 0.05 for all time points). Oral P4 resulted in significantly decreased body weight (−2.5%) compared with intravaginal P4 (+3.6%) (P = 0.0001). Markers of breast proliferation, sex steroid receptor expression, and endometrial area did not differ significantly between oral P4 and intravaginal P4 treatments (P > 0.1 for all).

Conclusions: Despite different pharmacodynamic profiles, oral and intravaginal P4 had similar effects on biomarkers in the postmenopausal breast.

©2007The North American Menopause Society


Article Tools


Article Level Metrics

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.