The overall aim of the comparative effectiveness of magnetic resonance imaging in breast cancer (COMICE) trial is to determine the potential benefits of the addition of magnetic resonance imaging (MRI) to the routine techniques employed for loco-regional staging of primary breast cancer, to both the patient and the National Health Service.

The study objectives are to evaluate the role of MRI in reducing the re-operation rates following primary excision between those planned by conventional triple assessment and those planned by triple assessment plus DCE MRI. Additionally, an economic evaluation from a societal perspective of the cost-effectiveness between the two arms will be performed.

The study design consists of a multicentre, randomised, controlled, open, fixed sample, parallel group trial with equal randomisation, of women with biopsy proven primary breast cancer who are scheduled for wide local excision. Patients (1,850) will be randomised to receive MRI or no further investigations. A pragmatic approach to trial design has been chosen so that results will be generalisable in clinical practice and to reduce unnecessary trial costs that are protocol driven.

Additional factors examined include the following: studying ipsilateral breast tumour recurrence rates; subsequent chemotherapy/radiotherapy rates; quality of life issues; risk factors for referral for MRI; accuracy of loco-regional staging; percentage of patients undergoing a change in clinical management after MRI; and follow up of MRI only detected lesions.