The effect of adjuvant carboplatin-based chemotherapy in stage I triple-negative breast cancer: A systematic review and meta-analysis of randomized controlled trials.

Abstract

e12523 Background: Carboplatin has been shown to improve pathologic complete response and disease-free survival (DFS) in patients with stage II-III triple-negative breast cancer (TNBC); however, the role of carboplatin in stage I TNBC is debated. For high-risk stage I TNBC, taxane plus cyclophosphamide (TC)-based regimens +/- anthracyclines are commonly used. We aimed to assess the impact of adjuvant carboplatin-based regimens on DFS in stage I TNBC. Methods: We performed a systematic search of PubMed, Embase, and Cochrane databases for randomized controlled trials (RCTs) published upto January 2026 comparing adjuvant carboplatin-based versus non-carboplatin-based chemotherapy in stage I-III TNBC. Trials which included DFS by pT1 or stage I subgrouping were eligible for inclusion. The primary outcome was DFS in the pT1 or stage I group; secondary outcomes were DFS in the pT2+ or stage II/III group and adverse events (AEs) in all patients. Meta-analysis was conducted using a random-effects model in R version 4.5.2. Heterogeneity was assessed with I² statistics. Results: Five RCTs with 2,692 patients were included, of which 1,261 (46.8%) had pT1 disease. Among these, 643 (51%) received adjuvant carboplatin-based regimens, compared to 618 (49%) who received non-carboplatin-based regimens. Carboplatin-based regimens improved DFS in pT1 (stage I) disease compared to non-carboplatin-based regimens (HR 0.62; 95% CI 0.44-0.85; P = 0.003). DFS was also improved with carboplatin-based regimens in patients with pT2+ disease (stage II/III) (HR 0.70; 95% CI 0.53-0.93; P = 0.014) and in the overall population (HR 0.63, 95% CI 0.51-0.78, P < 0.001) compared to non-carboplatin-based regimens. No significant differences were observed between carboplatin-based and non-carboplatin based regimens for either all-grade (RR 1.04, 95% CI 0.98-1.10, P = 0.154) or grade 3/4 (RR 1.04, 95% CI 0.72-1.50, P = 0.834) hematologic and non-hematologic AEs. Conclusions: Adjuvant carboplatin-based chemotherapy improves DFS compared to non-carboplatin-based chemotherapy in early-stage TNBC, including in patients with pT1 disease, without a corresponding increase in toxicity. These findings support consideration of carboplatin in the adjuvant treatment regimen in patients with high-risk stage I TNBC.