Background: Estrogen receptor (ER) and progesterone receptor (PgR) status at the time of breast carcinoma surgery is used as a marker of both prognosis and hormone dependency to guide adjuvant therapy. The authors studied the influence of hormonal milieu at the time of surgery on ER and PgR levels.
Methods: A population of 2020 patients with breast carcinoma, including 575 premenopausal women, was analyzed. ER and PgR levels were determined by radioligand binding assays (cutoff values, 10 fmol/mg). Serum estradiol (E2), progesterone (Pg), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels obtained on the day of surgery were used to define the menstrual cycle phase in premenopause.
Results: In premenopause, there was a higher proportion of ER positive (ER+) tumors in the follicular phase (62%, n = 316) than in the ovulatory phase (51%, n = 59) and the luteal phase (53%, n = 200, P = 0.03). The mean ER level was also higher in the follicular phase (30 fmol/mg) than in the ovulatory phase (20 fmol/ mg) and the luteal phase (25 fmol/mg, P < 0.001). The percentage of PgR positive (PgR+) tumors tended to be higher in the ovulatory phase (85%) than in the follicular (78%) and luteal (72%) phases (P = 0.11). The mean PgR was also higher in the ovulatory phase (177 fmol/mg) than in the follicular and luteal phases (134 and 92 fmol/mg, respectively; P < 0.001). The percentage of ER+ tumors was higher among menopausal women than among premenopausal women (67% vs. 59%, respectively; P < 0.001). Conversely, the percentage of PgR+ tumors was lower among menopausal women than among premenopausal women (65% vs. 78%, respectively; P < 0.001). In premenopause, there was a weak negative correlation between ER and E2 levels. No correlations were found between levels of ER and Pg and levels of FSH and LH or among levels of PgR and E2, Pg, and FSH and LH in premenopausal and menopausal women.
Conclusions: Changes in ER and PgR levels in breast carcinoma during the menstrual cycle and menopause suggest that interpretations of hormone dependency on the basis of steroid receptor values should take into account hormonal status at the time of surgery.