Participant enrollment

This prospective randomized controlled trial was approved by the Ethics Committee of West China Hospital of Sichuan University. Written informed consent was obtained from all participants. The study was registered with the Chinese Clinical Trial Register on September 21, 2014 (Registration number: ChiCTR-TRC-10001043).

Women aged 18–70 years old with locally advanced breast cancer confirmed by core needle biopsy were eligible for our study. Locally advanced breast cancer was classified as clinical stage IIB or III according to the American Joint Committee on Cancer staging system. Before randomization, baseline chest radiography, abdominal computed tomography (CT) or magnetic resonance imaging, and bone scintigraphy were performed to exclude distant metastases. Other eligibility criteria were an ECOG performance status of 0–1; normal cardiac function; no history or evidence of abnormal hematologic, renal, or hepatic function; and no history of other neoplasm (except non-melanoma skin cancer or curatively treated carcinoma in situ of the cervix).

Patients were excluded if they were pregnant; had received prior breast cancer surgery or systemic therapy; had uncontrolled concurrent illness such as serious viral, bacterial, or fungal infections, peptic ulcers or diabetes, or autoimmune diseases; had a history of severe hypersensitivity reactions to chemotherapeutic regimens; or had any other illness deemed by the physician to affect chemotherapy tolerability.

Treatment

With simple randomization, the participants were randomly assigned to the PE arm or the FEC arm. In the PE arm, intravenous infusion of epirubicin 30–40 mg/m² and paclitaxel 70–80 mg/m² were administered concurrently on days 1, 8, and 15 of every 4-week cycle. In the FEC arm, intravenous infusion of 5-fluorouracil 500 mg/m², epirubicin 100 mg/m², and cyclophosphamide 500 mg/m² were administered on day 1 of every 3-week cycle. Antimimetic drugs were administered prophylactically 30 min before the chemotherapeutic regimen was administered. During NACT, granulocyte colony-stimulating factor (G-CSF) support was required if the neutrocyte count dropped to <1.0 × 10⁹/L.

Surgery was undertaken within 1–2 weeks of NACT completion. According to the tumor characteristics and patient preference, women underwent BCS or mastectomy. Those considered eligible for BCS had a single tumor <3 cm in diameter, with the distance between the tumor edge and nipple being ≥3 cm, had no diffuse lesion or skin involvement, and were not contraindicated for radiotherapy. All patients who underwent BCS also underwent postoperative radiotherapy. All these patients underwent axillary lymph node dissection for nodal assessment.

All study visits were completed at the Breast Cancer Center of West China Hospital. At the beginning of each cycle, history taking, physical examination, and hematologic assessment were conducted to evaluate safety. The NACT schedule was delayed if the left ventricle ejection fraction (LVEF) decreased by 15% or if the patient showed symptoms of congestive heart failure, a severe hypersensitive reaction, or other adverse events during treatment. In the PE arm, if the patients had severe neutropenia (neutrophil count <1.0 × 10⁹/L), febrile neutropenia (grade 2 and above), or peripheral neuropathy (grade 2 and above), the dose of epirubicin and paclitaxel was reduced by 15%.

Participants were withdrawn if they had disease progression or developed severe adverse events (e.g., grade 3 or 4 non-hematologic toxicity), or at their request.

Efficacy assessments

Physical examination and imaging data (ultrasonography for tumor response assessment and CT scan for metastasis monitoring) were carefully recorded for clinical assessments before treatment, every two cycles during NACT, and before surgery. The tumor response was assessed by experienced oncologists and was classified as clinical complete response (cCR), partial response (cPR), stable disease (cSD), or progressive disease (cPD). In particular, the clinical tumor response was defined as the achievement of cCR and cPR. Any controversy was solved by discussion with a third oncologist. Tumor responses were used to dictate management strategies. Those showing a cCR, defined as the disappearance of the breast tumor and enlarged nodes on clinical assessments, could undergo surgery. Those showing a cPR, defined as a reduction of ≥30% in the three largest perpendicular tumor diameters, could complete at least four NACT cycles and then undergo surgery. Those with cSD, defined as a tumor reduction of <30%, or those with cPD, defined as an increase of ≥20% in the target tumor diameter or the emergence of a new tumor, could switch NACT regimens or undergo surgery as desired.

Postoperative pathologic assessments were conducted by pathologists at the Pathology Department of West China Hospital. A pCR was defined as the complete disappearance of the invasive tumor in the breast and lymph nodes. Residual ductal carcinoma in situ (DCIS) alone was also classified as pCR. Before the assessments and data analysis, the two groups were renamed as group 1 or 2 without detailed information on the NACT provided. Therefore, the surgeons who assessed the suitability for BCS, the pathologists who assessed the postoperative specimens, and the statisticians who performed the analysis were all blinded.

Safety assessments

All adverse events were recorded and graded according to the National Cancer Institute Common Toxicity Criteria (version 2.0). All women who underwent at least 1 cycle of chemotherapy were included in the safety analysis. Only grade 3–4 adverse events were analyzed.

Statistical analyses

The sample size was estimated to detect a pCR rate difference of 25% for the PE arm and 10% for the FEC arm. The assumed dropout rate was 10%. A sample size of 218 participants was sufficient to provide an 80% power to detect a pCR improvement of 15% in each arm with a type I error rate of 0.05.

All data were analyzed based on the intent-to-treat principle at randomization. Descriptive data were used to analyze patient characteristics. Quantitative data were compared using an independent sample t test, and qualitative data were compared using the Chi square test. Ranked data were compared using a non-parametric test. Statistical tests were considered significant with a two-sided P value of <0.05. All data were analyzed using SPSS version 16.0 (SPSS Inc., Chicago, IL, USA).

Patient characteristics

The results of randomization and treatment assignment are shown in Fig. 1. Between March 2010 and September 2013, 300 patients were enrolled, but 7 of them withdrew prior to treatment. Of the remaining 293 patients, 151 were assigned to the FEC arm, and 142 were assigned to the PE arm. The baseline patient characteristics of the two groups were evenly matched and are shown in Table 1. The median ages were 47 (range 27–69) years for the FEC arm and 47 (range 24–68) years for the PE arm. During chemotherapy, 16 patients (10 in the FEC arm and 6 in the PE arm) had declined further treatment; 15 (9 in the FEC arm and 6 in the PE arm) were lost to follow-up; and 34 (22 in the FEC arm and 12 in the PE arm) had switched chemotherapy regimens due to unsatisfactory outcomes or toxicities.

Characteristic	FEC arm [cases (%)]	PE arm [cases (%)]	P value
Total	151	142
Age (years)			0.430
≤35	5 (3.31)	8 (5.63)
>35	146 (96.69)	134 (94.37)
Menopausal status			0.263
Premenopausal	31 (20.53)	22 (15.49)
Postmenopausal	120 (79.47)	120 (84.51)
Clinical tumor stage			0.075
T2	106 (70.20)	86 (60.56)
T3	43 (28.48)	52 (36.62)
T4	2 (1.32)	4 (2.82)
Clinical nodal status			0.497
Involved	130 (86.09)	126 (88.73)
Not involved	21 (13.91)	16 (11.27)
ER/PR status			0.533
Positive	96 (63.58)	89 (62.68)
Negative	47 (31.13)	52 (36.62)
Missing	8 (5.30)	1 (0.70)
HER2 (IHC staining)			0.189
0/1+	64 (42.38)	66 (46.48)
2+	31 (20.53)	26 (18.31)
3+	45 (29.80)	47 (33.10)
Missing	11 (7.28)	3 (2.11)

PE weekly paclitaxel–epirubicin regimen, FEC tri-weekly 5-fluorouracil–epirubicin–cyclophosphamide regimen, ER estrogen receptor, PR progesterone receptor, HER2 epidermal growth factor receptor-2, IHC immunohistochemistry

Clinical response

During chemotherapy, three assessments were performed to grade the clinical response to these two regimens (Table 2). The results of the last assessment for individual participants are shown in Fig. 2. The clinical response rates were significantly higher in the PE arm than in the FEC arm (76.55% vs. 56.95%, P = 0.001). Those in the PE arm achieved higher cPR and lower cSD rates than those in the FEC arm (cPR rate: 70.92% vs. 54.30%, P = 0.006; cSD rate: 14.79% vs. 30.46% P = 0.002). Two patients in the PE arm developed distant metastasis after 4 cycles of NACT.

Group	First assessment [cases (%)]	Second assessment [cases (%)]	Third assessment [cases (%)]
FEC arm	151	132	68
cCR	0 (0.00)	1 (0.76)	3 (4.41)
cPR	70 (46.36)	76 (57.58)	51 (75.00)
cSD	67(44.37)	45 (34.09)	13 (19.12)
cPD	6 (3.97)	7 (5.30)	1 (1.47)
Missing	8 (5.30)	3 (2.27)	0 (1.47)
PE arm	142	121	49
cCR	1 (0.70)	6 (4.96)	5 (10.20)
cPR	97 (68.31)	92 (76.03)	41 (83.67)
cSD	35 (24.65)	20 (16.53)	2 (4.08)
cPD	3 (2.11)	3 (2.48)	1 (2.04)
Missing	6 (4.23)	0 (0.00)	0 (0.00)

FEC tri-weekly 5-fluorouracil–epirubicin–cyclophosphamide regimen, PE weekly paclitaxel–epirubicin regimen, cCR clinical complete response, cPR clinical partial response, cSD clinical stable disease, cPD clinical progressive disease

Surgery and pathologic response

Among the 293 patients, 262 underwent surgery (132 in the FEC arm and 130 in the PE arm). Among them, 219 patients (114 in the FEC arm and 105 in the PE arm) had completed at least 4 cycles of NACT; 33 (22 in the FEC arm and 11 in the PE arm) had switched chemotherapy regimens.

Safety