Reliability of Magseed® marking before neoadjuvant systemic therapy with subsequent contrast-enhanced mammography in patients with non-palpable breast cancer lesions after treatment: the MAGMA study.

Purpose: To assess the reliability of excising residual breast cancer lesions after neoadjuvant systemic therapy (NAST) using a previously localized paramagnetic seed (Magseed®) and the subsequent use of contrast-enhanced spectral mammography (CESM) to evaluate response.

Methods: Observational, prospective, multicenter study including adult women (> 18 years) with invasive breast carcinoma undergoing NAST between January 2022 and February 2023 with non-palpable tumor lesions at surgery. Radiologists marked tumors with Magseed® during biopsy before NAST, and surgeons excised tumors guided by the Sentimag® magnetometer.