Efficacy and Safety of Dose-dense Chemotherapy (ddEC-ddP) for Neoadjuvant Chemotherapy of HER2-negative Breast Cancer

Neoadjuvant chemotherapy refers to systemic chemotherapy as the first step for treating breast cancer patients before planned local treatment like surgery for those without distant metastasis. Randomized trials of chemotherapy have demonstrated similar long-term outcomes when patients were given the same treatment preoperatively compared with postoperatively. It is reported that preoperative neoadjuvant chemotherapy can facilitate breast conservation, render inoperable tumors operable and provide important prognostic information at an individual patient level based on response to therapy.

According to the recommendation of National Comprehensive Cancer Network (NCCN) guideline, patients with inoperable breast cancer, such as inflammatory breast cancer, N3 nodal disease and T4 tumors are candidates for preoperative systemic therapy. As for those operable patients with HER2-positive disease and triple-negative breast cancer (TNBC), if T ≥2 or N ≥1, or large primary tumor relative to breast size in a patient who desires breast conservation, neoadjuvant chemotherapy is also preferred. Based on the results of NSABP-27 and Aberdeen clinical trials, chemotherapeutic drugs including taxanes (such as docetaxel, paclitaxel) and anthracyclines (such as doxorubicin, epirubicin) have become the standard neoadjuvant chemotherapy regimens for early operable patients and for HER2-negative breast cancer patients, anthracyclines combined with cyclophosphamide followed by docetaxel is mostly common used.

Limited to myelosuppression and bone marrow repair, conventional chemotherapy cycle is usually set once every 3-4 weeks. Recent years, the application of granulocyte colony stimulating factor (G-CSF), which can shorten the recovery time of leukocytes, enables dose-dense chemotherapy (maximum tolerable dose, every 2 weeks as a cycle) to become a treatment option for high-risk patients. The concept of dose-dense chemotherapy is based on a mathematical model developed by Norton and Simon, and relies on an understanding of Gompertzian model of tumor growth. Gompertzian kinetics explain that human neoplasms do not grow in an exponential fashion, instead the cell-doubling time becomes progressively longer as the tumor growth. Thus, cancer treatments that reduce the size of a tumor can promote faster tumor regrowth between treatments indirectly. So Norton-Simon hypothesis suggests that the most effective strategy is to expose the tumor to cytotoxic agents as frequently as possible to minimize regrowth between cycles.

The CALGB 9471 used a randomized, 2×2 factorial design to prospectively compare sequential doxorubicin, paclitaxel, cyclophosphamide with concurrent doxorubicin and cyclophosphamide followed by paclitaxel, and to compare dose-dense schedules with conventional schedules. A total of 2005 node-positive, previously untreated patients were enrolled. At a median follow-up of 36 months, dose-dense treatment significantly improved disease-free survival (DFS) and overall survival (OS) compared with conventionally scheduled treatment. The GIM2 study also demonstrated that dose-dense adjuvant chemotherapy (FEC-P and EC-P every 2 weeks a cycle) improved DFS and OS compared with standard interval chemotherapy (every 3 weeks a cycle). However, the studies on dose-dense chemotherapy is mostly based on postoperative adjuvant chemotherapy. We aim to conduct a prospective, randomized, open-label, multi-center clinical study to compare the efficacy and safety of dose-dense chemotherapy (dd epirubicin/cyclophosphamide (EC) followed by dd paclitaxel (P)) and conventional chemotherapy (epirubicin/cyclophosphamide (EC) followed by docetaxel (T)) as preoperative neoadjuvant chemotherapy in the treatment of HER2-negative breast cancer in Chinese population.