New Techniques to evAlUate Response to neOadjuvant Treatments in bReast cAncer (AURORA)

The role of neoadjuvant chemotherapy (NAC) in breast cancer is well established. In inoperable patients at the time of diagnosis, the goal of NAC is to achieve a pathologic complete response (pCR) which has shown that it improves disease-free survival when compared to those cases with residual tumoral cells. Detection of the presence of residual disease is crucial for surgical planning; the ultimate goal would be to avoid surgery in those patients who achieve a pCR, though nowadays validated techniques with power enough to detect this residual disease are lacking.

Currently, several imaging techniques for NAC response assessment are being used (magnetic resonance imaging -MRI-, mammography and ultrasound), with good correlation in partial response, but they lack power in predicting complete pathological response; among them, nowadays the most accurate is MRI. In recent years, the use of the diffusion-enhanced images have been proposed for the quantitative characterization and for helping to improve the specificity of dynamic contrast study.

The investigators propose to use a bi-exponential model, IVIM (Intravoxel incoherent motion), which differentiates between microperfusion used by microvascular blood flow from the diffusion of water. Kurtosis (DKI by Diffusion Kurtosis imaging) which quantifies the deviation from the Gaussian pattern and diffusion tensor image (DTI) which provides information on the microstructure and pathophysiology tumor, presenting a statistically significant relationship with tumor cellularity. Preliminary studies have reported promising results for the evaluation of the early response to systemic treatment in breast cancer patients. Its utility for NAC response assessment in these patients will be analysed.

Recent studies have evaluated the application of contrast mammography in the assessment of the response to NAC, with MRI-like results. It is a faster and cheaper technique compared to MRI radiological evaluation of the response after NAC through this technique will be assessed and compared its results with the different techniques used in previous studies / in daily practice.

Shear wave elastography is a very useful tool for the quantitative assessment of the tissue hardness that is widely used for differentiating benign lesions from malignant ones. Nowadays some studies are investigating its usefulness in the assessment of the radiological evaluation after NAC, with promising results in terms of early evaluation. In this study, the elastography will be performed on pre surgical evaluation and its correlation with pathological anatomy.

In order to validate the technique, in those patients with a radiological complete response by all the radiological imaging methods, a stereotactic biopsy will be performed before surgery. After that, a comparison will be done between the results of the pre surgical biopsy and the definitive pathology of the specimen. If the false negative rate of the presurgical assessment including the biopsy are below 5%, patients could spare surgery when there is a complete radiological response. Objectives :

To evaluate if patients with complete radiological response after NAC, in this setting can be spared breast surgery. . - To determine if IVIM, KURTOSIS or DTI diffusion sequences in MRI can assess the response to NAC better than conventional sequences and, thus, be able to avoid the use of intravenous contrast in the MRI study in the future. - To determine whether the study of breast elastography with shear wave technology, is more sensitive or specific in the detection of residual tumor after NAC in breast cancer. - To determining whether contrast enhanced mammography helps us to assess the response to NAC in breast cancer, compared to MRI standard practice.

The expected results are:

False negative rate of pre-surgery biopsy <5%. Achieve a sensitivity >80% for the radiological tests in predicting pCR for selected tumoral subtypes (Triple Negative and HER2 enriched tumors).

Noninferiority of contrast mammography compared to breast MRI in determining the response to NAC.