Neoadjuvant systemic therapy in breast cancer: Brazilian guidelines aligned with international best practices

The assessment of response to neoadjuvant systemic therapy (NST) is a critical pillar in defining the multidisciplinary therapeutic strategy in breast cancer. This consensus aimed to establish national guidelines for imaging assessment of NST, based on the best scientific evidence adapted to the Brazilian context. To this end, a panel of experts was formed, composed of breast radiologists, breast surgeons, oncologists, onco-radiotherapists and breast patholo-gists. The methodology was based on a systematic literature review, followed by face-to-face discussions and rounds of virtual voting (adapted Delphi method), defining consensus when agreement was =75%. As a result, radiological response criteria were standardized, and accuracy, false-negative, and positive rates were determined, as well as the role of mammography, ultrasound, magnetic resonance imaging, and tomosynthesis, stratified by molecular subtypes. Additionally, recommendations were established for marking the breast lesion and axillary lymph nodes before the start of treatment. Finally, the role of other imaging techniques, such as contrast-enhanced mammography and pos-itron-emission tomography/computed tomography, was discussed, as well as the impact of artificial intelligence as tools for evaluating the response to SNRT.