The HER2-intermediate patients more frequently tended to have progesterone receptor (PR)-negativity and higher nuclear grade in the EBC cohort, and showed a higher proportion of patients aged ≥ 55 years compared with the HER2-negative group in the MBC cohort.
In metastatic breast cancer (MBC), expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2) guides treatment selection.
Other immunostains including mammaglobin (MGB), gross cystic disease fluid protein 15 (GCDFP-15), estrogen receptor (ER) and progesterone receptor (PR) are also used in diagnosing metastatic breast cancer.
The primary aim of this retrospective study was to investigate intraindividual correlation of estrogen receptor (ER) status, progesterone receptor (PR) status, and HER2 status between primary breast cancer and metastatic breast cancer (mBC).
Baseline characteristics were as follows: 65% had prior adjuvant chemotherapy, 55% had prior chemotherapy for metastatic breast cancer; mean age was 48 years (ranges 32 to 70); 30% estrogen receptor (ER) or progesterone receptor (PR)+, 70% ER/PR/Human Epidermal Growth Factor Receptor 2 (HER2)- and 0% HER2+.
Previously, we reported that androgen receptor (AR), but not estrogen receptor (ER) or progesterone receptor (PR), is predictive of response to the synthetic progestin, medroxyprogesterone acetate (MPA), in a cohort of 83 patients with metastatic breast cancer.
Reduction of human metastatic breast cancer cell aggressiveness on introduction of either form a or B of the progesterone receptor and then treatment with progestins.
Medroxyprogesterone acetate (MPA), which is frequently used as second line hormonal therapy for the treatment of metastatic breast cancer, binds with high affinity to the progesterone receptor (PR).