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

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. 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. 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. 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.