Receptor status conversion between primary and recurrent/metastatic breast cancer: A single institutional study.

Abstract

e14735 Background: Hormone receptor and HER2 status have both predictive and prognostic implications in breast cancer (BC). Studies report differences of 3% to 54% for Estrogen receptor (ER), 5% to 78% for Progesterone receptor (PR), and 0% to 34% for HER2 between primary (P) and recurrent/metastatic breast cancer (RMBC). To evaluate this difference, we conducted an observational single institution study in adult patients (pts) ≥ 18 years with RMBC. Methods: After IRB approval, we conducted a retrospective chart review of pts diagnosed with RMBC between January 1st, 2010 and October 31st, 2018, with history of PBC. We recorded age at PBC diagnosis, stage, tumor type, receptor status, initial treatment, age at RMBC diagnosis, if biopsy performed, receptor status and survival. We studied the differences in ER, PR and HER2 receptors between P and RMBC. Descriptive statistics was used for analysis. Results: We found a total of 179 pts in the time interval. Median age was 54 ± 13.2 years at PBC diagnosis, 98.9% females, 1.1% males. 187 events were recorded. At PBC diagnosis, 27.4% had Stage I, 37.4% had Stage II and 31.8% had Stage III disease. Tumor type was ductal in 83.8% and lobular in 12.2%. 78.8% was ER+, 68.7% was PR+ and 14% was HER2+. 70.9% received chemotherapy, 12.8% received HER2 therapy and 67% received hormonal therapy. Age at RMBC was median of 61 ± 13.1 years. Biopsy was done in 93.3%. Time between PBC and RMBC ranged from 7 and 324 months. 31.3% had local recurrence and 68.7% had distant disease. In RMBC, 59.2% was ER+, 41.9% was PR + and 13.4% was HER2 +. 58.7% are alive and 38% deceased. With RMBC, 19.2% who were ER+ became ER-, 4.9% who were ER- became ER+, 37.5% who were PR+ became PR-, 8.6% who were PR- became PR+, 23.1% who were HER2+ became HER2-, 4.5% who were HER2 - became HER2+. In pts who became ER-/PR-, 88.5% received hormonal therapy and 61.5% received chemotherapy at the time of PBC. In pts who became HER2-, 83.3% received HER2 therapy at the time of PBC. Conclusions: In our study, we found a difference of 24.1% in ER, 46.1% in PR and 27.6% in HER2 between PBC and RMBC. It is recommended that patients with RMBC should have a biopsy to evaluate the receptor status as it would impact treatment and survival.