Neoadjuvant Chemotherapy for Early Breast Cancer: A Study on Response Rate and Toxicity

Background: Neoadjuvant chemotherapy (NACT) is widely used in patients with high-risk HER2-amplified (HER2+) or triple negative early breast cancer (TNBC). Advantages of NACT include allowing less extensive surgery, assessing response to treatment and guiding adjuvant therapy. NACT-related toxicities are common and can result in treatment alterations and hospitalisation, which may adversely impact outcomes. Aim: To assess NACT treatment in Hawke's Bay (HB), New Zealand, by evaluating pathologic complete response (pCR) rates and toxicities of different regimens. Method: Data were retrospectively obtained from medical records of NACT patients. pCR rates were compared to results from the previous literature. Toxicity was assessed by recording severe (grade 3 or above) toxicities, treatment-limiting toxicities (those leading to dose reductions, dose delays or early cessation) and hospitalisations for different NACT regimens. Results: A total of 71 NACT patients were included. pCR rates for HER2+ disease and TNBC were 19/45 (42%) and 8/24 (33%), respectively. The most common severe toxicities were diarrhoea, anaemia and febrile neutropaenia (all 16%) in FEC-D (5-fluorouracil/epirubicin/cyclophosphamide + docetaxel +/- carboplatin +/- immunotherapy) patients, neutropaenia (50%) in FEC-DH (FEC-D + trastuzumab +/- pertuzumab) patients and diarrhoea (38%) in TCH (docetaxel/carboplatin/trastuzumab +/- pertuzumab) patients. Comparing treatment-limiting toxicity in FEC-DH vs. TCH, 9/16 (56%) vs. 13/21 (62%) had dose reduction, 2/16 (13%) vs. 8/21 (38%) had dose delay, 1/16 (6%) vs. 5/21(24%) had early cessation and 6/16 (38%) vs. 13/21 (62%) were hospitalised, respectively. Conclusions: NACT was associated with high rates of severe and treatment-limiting toxicity. Despite this, pCR rates were consistent with the previous literature. With the caveat of small patient numbers, FEC-DH-based therapy was associated with fewer dosing delays, early cessations and hospitalisations compared with TCH-based therapy.