Outcomes for Patients with Non-metastatic Triple-negative Breast Cancer in New Zealand

Triple-negative breast cancer (TNBC) has inferior outcomes to other subtypes of breast cancer. We studied the demographics and baseline breast cancer characteristics of patients in New Zealand with TNBC and assessed survival outcomes and prognostic/predictive factors.

We searched the New Zealand breast cancer registry database and identified patients with TNBC without distant metastatic disease. We retrieved demographic, tumour characteristic and treatment information. Locoregional recurrence-free survival, breast cancer-specific survival (BSS), metastasis-free survival (MRFS) and overall survival were determined. Predefined univariate and multivariate analyses were carried out investigating the association of survival outcomes with treatment and tumour characteristics.

In total, 1390 patients were identified, with a median follow-up of 3.5 years. The median age was 55 years. Thirty-eight per cent were node positive and 79% were grade III. Mastectomy was carried out in 53%, adjuvant radiation delivered in 66% and chemotherapy in 69%. The significant predictive factors for overall survival, BSS and MRFS were radiotherapy, chemotherapy and neoadjuvant chemotherapy. The significant prognostic indicators were lymphovascular invasion, nodal status and tumour size. On Kaplan-Meier analysis, the 5 year overall survival was 72%. The median time to death for those who died was 3.55 years with 92% of deaths within 5 years. Seventy-four per cent of patients had distant metastasis as a first recurrence and isolated local recurrences occurred in only 4.5%. Metastatic disease occurred in lung (55.9%) and was in multiple sites in 51%.

We report a large population-based series of TBNC without distant metastatic disease at diagnosis highlighting the unique behavioural characteristics of TNBC. Traditional therapies are positively associated with survival outcomes, and yet, particularly in the setting of recurrent disease, prognosis remains poor. Increased research into more effective systemic agents and the most effective timing of delivery of these may result in improved outcomes.