Pathological responses and survival of patients with human epidermal growth factor receptor 2-positive breast cancer who received neoadjuvant chemotherapy including trastuzumab.

BACKGROUND: The effectiveness of neoadjuvant chemotherapy is evaluated on the basis of pathological responses and survival outcome, because achievement of a pathological complete response (pCR) is a good predictor of long-term survival. However, few studies have assessed the survival of breast cancer patients who received neoadjuvant chemotherapy including trastuzumab.
METHODS: The records of 161 breast cancer patients who received neoadjuvant chemotherapy between January 2006 and December 2011 were retrospectively reviewed. The patients were categorized into 4 subgroups on the basis of the status of the estrogen receptor (ER), the progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). HER2-positive patients received trastuzumab-based regimens. Pathological responses and survival were analyzed on the basis of breast cancer subtypes.
RESULTS: The pCR results obtained were: luminal A and B (ER and/or PR-positive, HER2-negative), 6.3 % (5/79 cases); luminal-HER2 hybrid (ER and/or PR-positive, HER2-positive), 25.0 % (5/20 cases); HER2-enriched (ER and PR-negative, HER2-positive), 63.0 % (17/27 cases); and triple-negative (ER and PR-negative, HER2-negative), 25.7 % (9/35 cases). Achievement of pCR was a good predictor of disease-free survival in the HER2-enriched group. Overall survival of patients with pCR was slightly, but not significantly, better in the HER2-enriched and triple-negative subgroups.
CONCLUSION: Responses and survival after neoadjuvant chemotherapy including trastuzumab of patients with HER2-positive tumors differed among disease subtypes. Our findings suggest that disease subtype is an important determinant of the efficacy of neoadjuvant chemotherapy.