Evaluation of Data Obtained From Three Common Imaging Techniques: Positron Emission Tomography (PET-CT), Breast Ultrasound, and Magnetic Resonance Imaging (MRI) After Neoadjuvant Chemotherapy in Patients With Breast Cancer

Breast cancer is the most common and most deadly malignant tumor in women. In the case of invasive breast cancer, cancer cells have invaded the tissues surrounding the tumor. Neoadjuvant chemotherapy (NAC) is a therapeutic strategy used in locally advanced invasive breast cancer, with the aim of reducing tumor size in order to increase the chances of breast preservation and reduce micrometastases. Accurate and reliable assessment of the locoregional response to NAC is essential because it allows for planning whether breast-conserving surgery is necessary. Today, three minimally invasive imaging techniques are used to assess the response to NAC and the size of residual tumor: ultrasound, MRI, and PET. In routine practice, the choice of performing one, two, or three imaging techniques after NAC varies from one healthcare facility to another. Currently, there are no international recommendations, and decisions are made during multidisciplinary team meetings (MDTs), which include radiologists, oncologists, pathologists, and gynecologists. A review of the literature has not established the superiority of one technique over another in determining the size of residual tumor after neonatal ablation (NAA). Several studies analyze each technique individually, but the methodologies differ. More recent studies compare ultrasound, MRI, and PET scans, but the small number of patients and the fact that some studies are retrospective make the results inconclusive. A prospective study conducted on a large number of patients, each examined using all three techniques after NAA and before surgery, would determine the most effective technique for assessing residual tumor size and, consequently, for deciding on the surgical procedure. The main objective of this study is to compare the data collected by each of the three imaging techniques after neonatal ablation (breast ultrasound, MRI, and PET-CT) with the histological data of the tumor excised at the time of surgery.