Detection of circulating tumor cells that predicts the efficacy of neoadjuvant chemotherapy for locally advanced triple-negative breast cancer.

Objective: This study aims to assess the predictive potential of circulating tumor cells (CTCs) and circulating tumor stem cells (CTSCs) in locally advanced triple-negative breast cancer (TNBC) undergoing neoadjuvant chemotherapy (NAC) compared to the RECIST 1.1 standard. Methods: We analyzed 112 patients with TNBC at the Liaoning Tumor Hospital. CTCs and CTSCs were evaluated before NAC, on the first NAC cycle day, and after NAC. We assessed the ability of positive CTSCs after the first cycle to predict NAC resistance (requiring regimen change) with a 91% specificity. Additionally, we analyzed CTC dynamics during the first NAC cycle to predict efficacy (often reaching MP4 or MP5) with 87% sensitivity and 80% specificity. Results: Positive CTSCs post-first cycle predicted NAC resistance with high specificity (91%). The gradual decline in CTCs during the first NAC cycle indicated NAC efficacy, allowing the regimen to continue with a sensitivity of 87% and specificity of 80%. Conclusion: This study suggests that positive CTSCs after the first NAC cycle predict resistance, thereby facilitating early detection (≥ 6 weeks earlier than RECIST). Gradual CTC reduction during the first cycle predicts efficacy, enabling regimen continuation. CTCs and CTSCs show promise as predictive markers for NAC efficacy in patients with locally advanced TNBC.