Vacuum-assisted Biopsy and Surgical Correlation in HER2-positive and Triple-Negative Breast Cancer Subtypes in MRI Responders After Neoadjuvant Systemic Therapy. BISUCO TRIAL.

Objective To evaluate the diagnostic efficacy of 7G image-guided vacuum-assisted biopsy (VAB) in predicting pathological complete response (pCR) after neoadjuvant systemic therapy (NST) in HER2+ or triple-negative (TN) breast cancer (BC) showing complete response (CR) or almost-CR on MRI. Methods A prospective study was conducted from June 2018 to October 2022 on 25 HER2+ or TN operable BC patients who achieved CR or almost-CR on post-NST MRI. Presurgery, stereotactic or US-guided 7G VAB of the tumor bed was performed, and the pathological findings were compared with surgical results to evaluate the negative predictive value (NPV), accuracy, sensitivity, positive predictive value (PPV), and specificity in predicting residual disease. Results All tumors were invasive ductal carcinoma, with TN BC accounting for 52% (13/25) and HER2+ for 48% (12/25). MRI showed CR in 60% (15/25) of cases and almost-CR in 40% (10/25). Stereotactic VAB was performed in 84% (21/25) of cases and US-VAB in 16% (4/25), using 7G needles (average 10 samples) in all the cases. Posttreatment changes were demonstrated in all cases. Pathological CR was observed in 80% (20/25) of VAB cases and 84% (21/25) of surgical cases. Vacuum-assisted biopsy had a 100% NPV (95% CI, 83.2-100.0), 97.6% accuracy (95% CI, 92.9-100.0), 100% sensitivity (95% CI, 39.8-100.0), 80% PPV (95% CI, 28.4-99.5), and 95.2% specificity (95% CI, 76.2-99.9). Conclusion Image-guided VAB with 7G needles in HER2+ or TN BC with CR or almost-CR in post-NST MRI demonstrated a 100% NPV for detecting residual carcinoma when sample correlation and representativeness were ensured. Additional studies with larger patient cohorts are needed to confirm these promising results and to potentially omit surgery through image-guided VAB in selected TN BC and HER2+ BC cases.