Scrape versus imprint cytology in sentinel lymph nodes of breast cancer patients after neoadjuvant therapy: Does combination add value?

Abstract Background The primary objective of this study is to evaluate the feasibility of cytological methods in intraoperative consultation for patients receiving neoadjuvant therapy (NT), to compare the sensitivity, specificity, and accuracy of imprint, scrape, and combined cytology, and to assess the reliability of these methods in lymph nodes (LNs) affected by treatment‐related changes. Additionally, this study aims to investigate the impact of metastatic tumor size on the diagnostic accuracy of cytological methods. Methods Ninety‐two patients who underwent sentinel LN sampling during breast surgery between June 2023 and December 2024 were included in this retrospective study. Diagnostic performance of imprint, scrape, and combined cytology was evaluated according to NT status, metastatic tumor size, and treatment‐related changes. Overall accuracy was assessed using Receiver operating characteristic (ROC) analysis, with pairwise comparisons performed using DeLong’s test. Results A total of 300 LNs were evaluated, of which 161 (53.6%) were from patients receiving NT. In this subgroup, imprint cytology showed high specificity but limited sensitivity, whereas scrape and combined cytology demonstrated higher sensitivity and overall diagnostic accuracy. ROC analysis showed significantly higher diagnostic performance for scrape and combined cytology compared with imprint cytology in patients receiving NT ( p = .005). Across all subgroup analyses, including metastasis size and therapy‐related changes, combined cytology consistently showed the highest sensitivity, whereas imprint cytology maintained the highest specificity. Conclusion Scrape cytology showed significantly higher diagnostic performance than imprint cytology, particularly after NT. Combined cytology improved performance compared with imprint cytology but did not significantly outperform scrape cytology.