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Discordance of hormone receptor, human epidermal growth factor receptor-2, and Ki-67 between primary breast cancer and synchronous axillary lymph node metastasis.

PURPOSE
We herein report the discordance rate between primary breast cancer and synchronous axillary node metastasis, its characteristics and its prognostic impact.


METHODS
One hundred and four patients with invasive breast cancer with synchronous axillary node metastasis who underwent surgery were included. Estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor-2 (HER2), and Ki-67 were stained by immunohistochemistry in both primary and node metastasis. The cut-off values of the ER/PgR and Ki-67 labeling index were set at 10% and 14%, respectively. HER2 was classified according to the ASCO/CAP guidelines.


RESULTS
Cases positive for ER, PgR, and HER2 were 65.4%, 51.0%, and 27.9% and those with a high Ki-67 labeling index were 47.1% in primary breast cancer, respectively, while they were 47.1%, 30.8%, 16.3%, and 75.0% in node metastasis, respectively. The discordance rates between primary and node were 28.8% for ER (positive in primary→negative in node/negative→positive 22.1%/6.7%), 31.7% for PgR (26.9%/4.8%), 13.5% for HER2 (12.5%/1.0%), and 43.3% for Ki-67 (high in primary→low in node/low→high 12.5%/30.8%). The proportions of labeled cells in primary/node were as follows: ER 42.7%/25.2%, PgR 32.1%/14.0%, Ki-67 20.3%/37.1% (p<0.01 each). Regarding the cut-off value of Ki-67 in node metastasis as defined by a receiver operating characteristic (ROC) analysis, the patients with values >33.2% tended to have a poor recurrence-free survival (RFS) (p=0.08).


CONCLUSIONS
The expression of hormone receptors tended to weaken while the proliferative status remained strong in axillary metastasis. A high Ki-67 labeling index in axillary lymph node metastasis may be a risk factor for recurrence.