Impact of Triple-Negative Breast Cancer Phenotype on Prognosis in Patients with Stage I Breast Cancer

PURPOSE: Although most patients with stage I breast cancer have a good prognosis, their clinical outcomes may vary significantly. We assessed clinical outcomes and prognostic factors in stage I breast cancer patients with and without triple-negative breast cancer (TNBC) phenotype. METHODS: Of 2,489 patients undergoing breast cancer surgery between January 1998 and December 2002, 554 (22.3%) had stage I breast cancer (tumor size ≤2 cm, and lymph node-negative). TNBC was defined as a primary tumor negative for estrogen and progesterone receptors (Allred scores <3/8) and for HER2/neu (0-1+ by immunohistochemistry). RESULTS: Of the 554 patients with stage I breast cancer, 78 (14.1%) had TNBC. A significant proportion of TNBC patients had histologic grade 3 tumors (47.4% vs. 34.5%, p=0.031) and tumors >1 cm (87.2% vs. 75.8%, p=0.028) and received adjuvant chemotherapy (79.5% vs. 44.7%, p<0.001). During a median follow-up time of 8.7 years, 72 patients experienced tumor recurrences; 18 (23.1%) in the TNBC group and 54 (11.3%) in the non-TNBC group (p=0.010), with cumulative 3-year rate of recurrence of 12.8% and 5.3%, respectively (p=0.010). Ten-year relapse-free survival (RFS; 75.6% vs. 87.5%, p=0.004) and overall survival (OS; 83.0% vs. 91.4%, p=0.002) rates were significantly lower in the TNBC group. Multivariate analysis showed that triple negativity and histologic grade were independent predictors of shorter RFS and OS. CONCLUSION: TNBC had more aggressive clinicopathologic characteristics and was associated with poorer survival in patients with stage I breast cancer. More intensive adjuvant chemotherapy or a different therapeutic strategy targeting this population is warranted.