Efficacy of adding neoadjuvant pembrolizumab to standard chemotherapy for triple-negative breast cancer: A systematic review and meta-analysis of real-world studies

Abstract

Objectives: To synthesise real-world data from comparative observational studies to assess the impact of neoadjuvant pembrolizumab plus chemotherapy (NAC+P) versus chemotherapy alone (NAC) on triple-negative breast cancer (TNBC) outcomes.

Methodology: We searched the websites of PubMed, Embase, Scopus, and Web of Science up to 26 March 2026. Pooled odds ratios (OR) with 95% confidence intervals (CI) were estimated using a random-effects model (DerSimonian-Laird) for pathologic complete response (pCR; six studies), axillary lymph node dissection (ALND; five studies), and breast-conserving surgery (BCS; five studies).

Results: Six studies comprising 1,288 patients (NAC+P: n=566; NAC: n=722) were included. NAC+P was associated with a significantly higher pCR rate (OR 2.84, 95% CI 1.62–4.99; p=0.0003; I²=80.8%) and a significantly lower ALND rate (OR 0.51, 95% CI 0.36–0.72; p=0.0001; I²=19.5%). No significant difference in BCS rate was observed (OR 0.99, 95% CI 0.75–1.31; p=0.953; I²=14.6%). Leave-one-out sensitivity analyses confirmed the direction of all findings. However, the magnitude and heterogeneity of pCR were sensitive to exclusion of a single study. No funnel-plot asymmetry was noted on Egger’s test. The small number of studies per outcome limited its reliability.

Conclusions: In practical settings, NAC+P notably increases pCR rates and reduces the need for ALND in TNBC, aligning with findings from randomised trials. The absence of a similar rise in BCS rates indicates that surgical choices are influenced by factors beyond pathological response alone.