The Impact of Preoperative Breast MRI in Newly Diagnosed Breast Cancer. A Prospective Study of Treatment Outcome in Patients Selected for Breast Conserving Surgery in a Norwegian Multidisciplinary Breast Cancer Clinic.

The aim of the study is to evaluate the impact of preoperative breast MRI on primary surgical treatment in a highly specialized multidisciplinary breast cancer clinic. The clinic serves a population of 237.000. The diagnostic tools routinely used are conventional mammography, ultrasound with core needle biopsy, and clinical examination including palpation of breast and axillary nodes. If indicated, the examination includes ultrasound examination and fine needle biopsy of axillary glands. We offer all patients selected for breast-conserving surgery preoperative breast MRI.

We include consecutively breast cancer lesions in women aged 35-75 in a prospective study, collecting data from January 2009 to December 2010. The patients are all selected for breast-conserving surgery based on the criteria recommended by the Norwegian Breast Cancer Group. That is, tumor ≤ 4 cm, or acceptable tumor:breast ratio, and age > 35. Multifocal lesions, defined as more than one tumor > 1 cm apart, size of tumor > 4 cm, or a large tumor:breast ratio, extensive ductal carcinoma in situ (DCIS), or known genetic disposition for breast cancer, indicates mastectomy according to these criterias. In addition, when postoperative radiation therapy is contraindicated, mastectomy is indicated. If the patients fill the criteria for breast-conserving surgery, they are offered preoperative breast MRI and included in the study. Patients who either choose mastectomy, or does not get a breast MRI for technical reasons, are excluded from the study. Two experienced breast radiologists evaluate the breast MRIs, and three experienced breast radiologists study the mammographies and perform the ultrasound examinations and biopsies. All additional MRI findings are examined by ultrasound-guided biopsy and given a histological diagnose before it influence the surgical method.

A formal application has been presented to the regional ethical commitee. Since this is an observational study of established practice, the commitee replied that approval was not required.