Optimal duration of adjuvant chemotherapy for high-risk node-negative (N-) breast cancer patients: 6-year results of the prospective randomised multicentre phase III UNICANCER-PACS 05 trial (UCBG-0106)

{Purpose: Optimal duration of adjuvant chemotherapy in the treatment of early-stage breast cancer remained to be investigated rigorously for the standard regimens in widespread use in North America (doxorubicin/cyclophosphamide, AC) and Europe (5-fluorouracil/epirubicin/cyclophosphamide, FEC). Whether six cycles of FEC 100 present an advantage, or not, compared with only four cycles was tested directly in a phase III prospective multicentre trial. Patients and methods: Between 2002 and 2006, 1515 women between 18 and 65 degrees years of age, with node negative N(-) high-risk early-stage breast cancer, were included in the study following breast surgery and axillary lymph node dissection or procedure by sentinel node technique. Inclusion in the study required tumour size T >= 1 cm and at least one of the high-risk factors: T > 2 cm, negative oestrogen receptor/progesterone receptor (ER- and PR-), Scarff-Bloom-Richardson (SBR) grade II or III and age <= 35 degrees years. Patients were randomly assigned to either six FEC 100 (Arm A) or four FEC 100 (Arm B). The trial was powered to detect an absolute difference >= 6% in disease-free survival (DFS) at 5 degrees years. Results: At 6.1 degrees years median follow-up, with 91 (12%) events recorded in Arm A versus 106 (14%) in Arm B, no statistically significant risk increase was associated with four versus six FEC 100: DFS (hazard ratio (HR) Z 1.18; CI 95% [0.89-1.56]