T1N0 Triple Negative Breast Cancer: Risk of Recurrence and Adjuvant Chemotherapy

Adjuvant treatment of T1N0 breast cancer (BC) has evolved in recent years with chemotherapy options dependent on tumor size and cellular characteristics. Our goal is to describe the difference in outcome between T1N0 triple negative (TriNeg) and estrogen/progesterone receptor positive/her2/neu-negative BC. From our institute's registry, we identified primary BC patients diagnosed from 1998 to 2005, estrogen/progesterone receptor negative (ER-/PR-)/her-2/neu negative (her2-) (TriNeg = 110) and ER+/PR+/her2- (HR+/her2- = 919). Clinical diagnosis and treatment variables were chart abstracted. Vital and disease status were updated annually. Pearson chi-squared tests were used for bivariate analysis. Hazard ratios were calculated using the Cox proportional hazards model. Average patient age was 59 years, range 23-93 years and average length of follow-up was 4.22 years. T-stage distribution for HR+/her2- patients was 9% T1a (> 0.1, < 0.5 cm), 34% T1b (> 0.5 cm, < 1 cm), 57% T1c (> 1 cm, < 2 cm) and for TriNeg, 6% T1a, 21% T1b, and 73% T1c. Sixty-five per cent of T1b and 73% T1c TriNeg patients received chemotherapy versus 7% of T1b and 32% of T1c HR+/her2- patients with TriNeg patients more likely to receive doxorubicin/cyclophosphamide/paclitaxel combined therapy. Recurrence rates were the following, T1b: 8.7%, TriNeg (2/23) versus 0%, HR+/her2- (0/315) and T1c: 8.8%, TriNeg (7/80) versus 2.1%, HR+/her2- (11/523). Five year relapse-free survival was 98% in the HR+/her2- group and 89% in the TriNeg group (log rank test = 27.77, p < 0.001). The hazard ratio for recurrence in the TriNeg group was 6.57 (95% CI = 2.34, 18.49) adjusted for age, tumor size, and adjuvant chemotherapy. Triple negative T1N0 patients have greater recurrence risk in spite of more aggressive therapy by both number treated and adjuvant chemotherapy type even in a low-risk category. New treatment modalities specific for triple negative disease are urgently needed.