Preoperative Magnetic Resonance Imaging to Obtain Adequate Resection Margins (PRIMAR) Trial

Magnetic Resonance Imaging (MRI) of the breast preoperatively is a well-known imaging method in primary breast cancer and is only used as a complement to the standard imaging methods in complex cases, lobular cancer, patients with large tumors that need preoperative neoadjuvant therapy or for patients with dense breast tissue where the tumor is difficult to detect with the standard imaging methods. The MRI is not used as a standard diagnostic method, because of its lower specificity that may result in a higher false-positivity rate.

The advantage of the MRI with use of intravenously contrast agent (also called dynamic enhanced MRI), is its ability to simultaneously assess the tumor morphology and semiquantitative enhancement kinetics that evaluate the newly formed vessels as a tumor-specific feature. A fast-initial enhancement and wash-out (type III) is typically seen in malignancies, due to increased vascular permeability, density, and interstitial fluid. Furthermore, the breast MRI can identify preinvasive malignant lesions such as Ductal Carcinoma in Situ (DCIS) in the breast with a much higher sensitivity than mammography and most commonly manifests as non-mass-enhanced lesion on an MRI with intravenous contrast agent. Less frequently the DCIS manifests as a mass or a focus on MRI and is usually not visible on non-contrast enhanced MRI, because it is masked by the normal breast parenchyma. Few larger randomized trials have investigated the efficacy of preoperative MRI in breast cancer and its effect on involved histological margins after breast conserving surgery that lead to repeat surgery. Controversy still exists whether preoperative MRI of the breast can reduce the number of repeat surgery in breast cancer. We aim to investigate in this randomised study if a supplementary breast MRI preoperatively with an optimised MRI scan protocol can help surgical planning to detect the DCIS and invasive cancer such that tumor free resection margins can be obtained during breast conserving surgery (BCS) and the patients can avoid repeat surgery.

Methods:

The study will be performed as a clinical, open-label, prospective and randomized study. We will include 440 breast cancer patients, randomized to either MRI of the breast prior to BCS together with the standard methods: Ultrasound and mammography (220) or to standard methods only (220) at two different breast centers, Aarhus University Hospital (AUH) and Viborg Regional Hospital (VRH).

The MRI of the breast: Will be performed with a protocol with intravenous contrast agent, Dotarem on a 3 Tesla Siemens MRI at the Department of Radiology at AUH and a 1.5 Tesla Siemens MRI System at VRH, with breast adaptive coils and diffusions sequences. The MRI of the breast will be performed soon after the patient is included in this study and will not delay surgery. The MRI protocol consists of T2- and T1-weighted spin-echo sequences in the axial plane, a T2-weighted sequence, dynamic contrast enhanced subtracted series with intravenous contrast agent Dotarem and diffusions-sequences, with breast adaptive coils at each institution. The MRI images of the breast from VRH for each patient will be sent to AUH, where the images will be interpreted by an experienced breast radiologist, using the same picture archiving and communication system from Siemens Healthcare. The tumor and DCIS will be measured, localized anatomically and presented for the breast surgeon at each institution at Multi-Disciplinary-Team conferences at each institution. The size of the invasive tumor and the DCIS in the breast will be recorded and compared to the corresponding size on the standard methods with mammography and ultrasound.