Hormonal receptor, human epidermal growth factor receptor-2, and Ki67 discordance between primary breast cancer and paired metastases: clinical impact.

OBJECTIVE: As hormone receptor and human epidermal growth factor receptor-2 (HER-2) expression in primary breast tumors frequently differs from that of paired metastases, we first evaluated the discordance rate (DR) of estrogen receptor (ER), progesterone receptor (PgR), HER-2, and Ki67 in breast cancer patients and then assessed the discordance effect on prognosis.

METHODS: Of 145 cases reviewed, 120 with samples available from both primary tumors and paired metastases were included in the study. For each receptor, the DR was calculated as the proportion of discordant cases with respect to the total number of patients.

RESULTS: A change in ER status was observed in 19 cases (DR 16.4%), while PgR status was modified in 48 cases (DR 41.7%). HER-2 was altered in 21 cases (DR 17.5%), and Ki67 in 33 patients (DR 38.8%). Patients with Ki67 <20% had a significantly higher postrecurrence survival (PRS) compared to patients with Ki67 ≥20% (p = 0.0006). Patients with ER-positive tumors showed a trend towards higher PRS (p = 0.064) compared to ER-negative patients. No differences in PRS were seen among patients with altered PgR or HER2 status.

CONCLUSIONS: Changes in the cell biology of breast cancer metastasis would seem to occur and biopsy could potentially guide the choice of treatment and provide useful information on prognosis.