Common and discriminative clinicopathological features between breast cancers with pathological complete response or progressive disease in response to neoadjuvant chemotherapy.

PURPOSE: To clarify clinicopathological similarities and differences between breast carcinomas that achieve pathological complete response (pCR) to neoadjuvant chemotherapy (NAC) and those showing progressive disease (PD) during NAC, we compared pre-NAC clinicopathological characteristics between these tumors.

METHODS: Subjects comprised 32 patients (6%) achieved pCR and 33 patients (7%) showed PD of 494 patients (498 breasts) with stage II or III breast carcinoma who underwent anthracycline-based or taxane chemotherapy or both, followed by surgery, between 2000 and 2006. We compared patient characteristics before NAC, and histomorphology, immunohistochemistry, and molecular subtypes of tumors using pre-NAC biopsy samples. Immunohistochemistry included estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor-2 (HER2), epidermal growth factor receptor (EGFR), cytokeratin 5/6 (CK5/6). Molecular subtypes were defined by ER, PgR, HER2, EGFR, and CK5/6. We compared these factors between pCR and PD using univariate chi (2) testing and multivariate logistic regression analyses.

RESULTS: No significant differences between groups were seen regarding NAC regimens. Solid-tubular carcinoma (53% of pCR, 61% of PD), histological grade 3 (78% of pCR, 79% of PD), ER-status (91% of pCR, 82% of PD), and basal-like subtype (44% of pCR, 58% of PD) were often observed in both groups. In multivariate analyses, lower clinical N stage at diagnosis (P = 0.004) and HER2/ER-PgR- subtype (P = 0.020) were significantly associated with pCR.

CONCLUSIONS: Breast carcinomas achieving pCR or showing PD with NAC have common peculiar characteristics such as solid-tubular carcinoma, high grade, hormone receptor negativity, and basal-like subtype. Conversely, discriminative factors include clinical N stage at diagnosis and HER2/ER-PgR- subtype.