Diagnostic Performance of Ultrasonography and Mammography in Detecting Local Recurrence after Breast-Conserving Surgery: A Systematic Review and Exploratory Diagnostic Meta-analysis.

INTRODUCTION/BACKGROUND: Imaging surveillance after Breast-Conserving Surgery (BCS) is essential for identifying potentially curable local or ipsilateral breast tumor recurrence. Mammography (MG) remains the standard surveillance modality, but postoperative scarring, radiotherapy-related distortion, and breast density may reduce its interpretability. Ultrasonography (US) may provide complementary assessment of non-calcified soft-tissue abnormalities. MATERIALS AND METHODS: A systematic search of PubMed, Embase, Web of Science, the Cochrane Library, and Ovid MEDLINE was performed from database inception to August 2025. Eligible studies enrolled patients after BCS or breast-conserving treatment, evaluated MG and/or US for postoperative local or ipsilateral recurrence, and reported extractable diagnostic accuracy data. Study selection, data extraction, and QUADAS-2 assessment were conducted independently by two reviewers. Owing to marked threshold and methodological heterogeneity, modality-specific performance was summarized using paired forest plots, Hierarchical Summary Receiver Operating Characteristic (HSROC) curves, Area Under the Curve (AUC), and leave-one-out sensitivity analyses rather than simple pooled sensitivity/specificity estimates. RESULTS: Nine studies were included. Six studies contributed MG-specific data. MG sensitivity ranged from 0.25 to 1.00 and specificity from 0.51 to 1.00; the HSROC AUC was 0.752, and leave-one-out AUCs ranged from 0.732 to 0.839. Three studies contributed US-specific data. US sensitivity ranged from 0.50 to 0.95 and specificity was consistently high (approximately 0.98 in the included modality-specific studies); the HSROC AUC was 0.985, and leave-one-out AUCs ranged from 0.966 to 0.985. Because direct comparative evidence was limited and heterogeneous, no formal pooled superiority estimate was retained. DISCUSSION: The available evidence suggests that US may be a valuable complementary modality after BCS, particularly for soft-tissue or non-calcified recurrence, whereas MG remains important for detecting microcalcifications and architectural changes. The evidence base is limited by small numbers of studies, variable reference standards, older imaging technology in some reports, and incomplete reporting of recurrence morphology and surveillance timing. CONCLUSION: US appears to have complementary value in postoperative surveillance after BCS, but the current evidence does not justify replacing MG or making an unconditional claim that US is superior. Larger prospective, head-to-head studies using standardized imaging protocols and reference standards are warranted.