P2-08-09: 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.

Abstract

Abstract Background: The aim of the study was to evaluate the impact of preoperative breast MRI on primary surgical treatment in a specialized multidisciplinary breast cancer clinic. 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. Material and methods: We included consecutively 145 breast cancer lesions in 143 women (two had bilateral cancer) aged 35–75 in a prospective study, collecting data from January 2009 to December 2010. The patients were 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 filled the criteria for breast-conserving surgery, they were offered preoperative breast MRI and included in the study. Patients who either choose mastectomy, or did not get a breast MRI for technical reasons, were excluded from the study. Two experienced breast radiologists evaluated the breast MRIs, and three experienced breast radiologists studied the mammographies and did the ultrasound examinations and biopsies. All additional MRI findings were examined by ultrasound-guided biopsy and given a histological diagnose before it influenced the surgical method. Results: We excluded 28 patients from the study; 10 patients choose mastectomy, 13 patients were excluded due to problems with the MRI technology, and 5 patients were excluded for other reasons. Among the remaining 117 patients, 96 were treated by breast-conserving surgery, and 21 by mastectomy. The change of operative method was induced by the preoperative breast MRI in 16 patients, because of multifocality in 11 patients, and because of a more extensive tumor than discovered by conventional diagnostic tools, in 5 patients. Five patients had a secondary mastectomy, due to histopathological findings in the lump. In one patient preoperative MRI revealed cancer in the contralateral breast, and in one patient the additional findings on MRI resulted in preoperative systemic chemotherapy. The multifocality diagnosed on the preoperative MRI was confirmed on histopathological examination of the breast in 10/11 patients. In one patient who received preoperative systemic chemotherapy, the removed breast was without sign of malignant cells on microscopic examination. Discussion: In this prospective study preoperative breast MRI give additional information that have impact on the primary surgical treatment in 16/117 or 13,7% of the patients selected for breast-conserving surgery. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-08-09.