Real-world survival outcomes of neoadjuvant versus adjuvant chemotherapy in operable triple-negative breast cancer: a propensity score matched registry-based study.

Background and purpose: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype where the prognostic implications of primary systemic therapy followed by surgery, compared to up-front surgery and subsequent adjuvant chemotherapy (ACT), are yet to be outlined. This retrospective registry-based study aimed to compare survival outcomes between patients treated with neoadjuvant chemotherapy (NACT) versus ACT for operable TNBC in a real-world setting. Patient/material and methods: We included all patients treated with chemotherapy for operable TNBC in Sweden between 2008 and 2019 using the Swedish national research database BCBaSe 3.0. To reduce confounding by indication, we implemented propensity score matching (PSM) and main study outcomes were defined as distant disease-free survival (DDFS), breast cancer-specific survival (BCSS) and overall survival (OS).

Results: A total of 4,704 patients were included in the study, of which 1,183 received NACT. Following 1:1 PSM, 837 patients in each treatment setting were available for analyses. We found no statistically significant differences in terms of DDFS (adjusted hazard ratio [aHR] 1.18; 95% confidence interval [CI] 0.93 - 1.50), BCSS (aHR 1.10; 95% CI 0.83 - 1.45) or OS (aHR 1.07; 95% CI 0.82 - 1.39) between patients treated with NACT versus ACT. However, subgroup analysis of patients with clinically node-positive disease (cN+) demonstrated a significant DDFS benefit of NACT (aHR 0.65; 95% CI 0.47 - 0.90).

Interpretation: Overall, we found comparable survival among patients with TNBC treated with NACT or ACT. Considering the anticipated survival improvements when response-guided post-neoadjuvant strategies are implemented in clinical practice, our findings may support the use of NACT in operable TNBC.