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n Abstract: The purpose of this study is to determine how often breast magnetic resonance imaging (MRI) brings additional information that influences management of patients with breast cancer concerning surgical treatment, axillary lymph node approach, and systemic therapy. From July 2004 to July 2005, 99 patients recently diagnosed with breast cancer in clinical stages 0, I, and II were prospectively evaluated about their therapeutic plans, at first based on usual protocol (physical examination, mammography and ultrasound) and next going through bilateral breast MR. Examinations were carried out at 1.5 T on five sequences of FSPGR 3D for 90 seconds (four post-gadolinium diethylenetriaminepenta acetic acid 0.16 mM ⁄ Kg). Parameters analyzed on MRI were extension of primary lesion; detection of multifocality, multicentricity, or contra lateral lesion; muscular or skin involvement; and presence of lymph node involvement. Pathologic confirmation of additional lesions was achieved by core or excisional biopsy. MRI made 69 additional findings in 53 patients. Fifty-one findings were true-positives (51 ⁄ 69 = 73.9%) including 16 larger single lesions; 18 cases of multifocality; 7 cases of multicentricity; 3 cases of contra lateral lesion; 5 cases of lymph node involvement (one of them involved medial thoracic chain); 1 with muscular involvement; 1 with skin involvement. MRI has changed previous management plans in 44.4% of 99 patients. We observed increase in mastectomies (26.8%) on axillary lymph node dissection (25%) and changes on systemic therapy (20.2%), all because of additional MRI true-positive findings. Breast MRI alters significantly the rate of mastectomy, the approach of axillary chain for staging, and the use of systemic therapy because of its accuracy in evaluating breast cancer local extent. n

Background: Studying breast cancer, our data has demonstrated higher occurrence of large extensions and/or multiple synchronic malignant lesions in dense breasts. Following this investigation, we decided to correlate breast density with Ki67 on tumor specimens and disease extent on MRI. Methods: From August 2005 to April 2009, 193 consecutive patients diagnosed with breast cancer were evaluated about number and size of breast malignant lesions, about fibroglandular (FG) density on Mammography and about proliferation marker on immunohistochemistry of tumor cells. Fibroglandular density was classified using criteria: <50%; >50%. All patients had evaluation of hormonal receptors (estrogen and progesterone), HER2/neu and Ki67 on immunohistochemistry of tumor blocks. They were also submitted to bilateral breast MRI in 1.5 T Excite/GE equipment, 5 sequences FSPGR (90 seconds each, 1 preinjection, 4 postinjection of gadolinium 0.16 mM/kg, 3.5/0 thickness) to evaluate size of primary lesion and presence of additional malignant foci. Additional findings were submitted to pathological examination (core or excisional biopsy). Results: Among 193 patients, 66 (34%) presented FG density <50% and 127 (66%) had FG density >50%. Eighty one patients (42%) presented large single tumor (35 cases) and/or multiple synchronic malignant lesions (46 cases), which 16/81 (19%) had FG density <50% and 65/81 (81%) had FB density >50%. In 112/193 patients (58%) with small single tumor on MRI, 66 (59%) had density >50%. Expression of Ki67 was 30% positive or higher in 17/66 patients (25,7%) with FG density <50% and in 70/127 patients (55%) with FB density >50%. Correlation between high expression of Ki67 (30% or higher) and extent was significant for patients with large single tumor (17/35=48,5%), but not for patients with multiple synchronic lesions (11/46=24%). Expression of Ki67 was 30% positive or higher associated with HER2 overexpression (3+) or with triple negative tumors in 95% of both conditions (multiple synchronic or larger single tumors). Conclusions: This study demonstrated that dense breasts are associated with larger extensions of breast cancer and suggests that FB density can be correlated to higher expressions of Ki67 on immunohistochemistry, especially in single tumors. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6043.