Identification of Patients with Node-negative, Triple-negative Breast Cancer who Benefit from Adjuvant Cyclophosphamide, Methotrexate, and 5-Fluorouracil Chemotherapy

Aim: Triple-negative breast cancer (TNBC) has a relatively poor prognosis compared to other molecular subtypes of breast cancer. This study aimed to evaluate the role of adjuvant cyclophosphamide, methotrexate, and fluorouracil (CMF) in node-negative TNBC and to identify patients who could benefit from this therapy. Patients and Methods: We retrospectively reviewed the clinicopathological features and outcomes of patients with node-negative TNBC after surgery followed by either adjuvant chemotherapy with CMF or observation only. Results: Between January 2000 and December 2006, 276 patients with node-negative TNBC were eligible for inclusion in this study. The median follow-up time was 85.0 months by the end of 2010. The CMF (N=211) and observation (N=65) groups did not significantly differ with regard to T-stage, lymphovascular invasion (LVI), and tumour grade, but patients in the former group were on average younger (p<0.01). Adjuvant CMF was associated with favourable disease-free survival (DFS) (p=0.04). The CMF group also had a significantly lower locoregional recurrence rate than the observation group (0.4% vs. 9.2%, p=0.02). Subgroup analysis revealed that patients in the CMF group had significantly better DFS than those in the observation group among those with tumours larger than 2 cm (hazard ratio=0.38, p=0.02) and those who underwent partial mastectomy (hazard ratio=0.28, p=0.01). Conclusion: Adjuvant CMF chemotherapy was effective in reducing locoregional recurrence rate and prolong DFS in patients with node-negative TNBC, particularly in those with tumours of more than 2 cm or who had undergone partial mastectomy.