So Yoon Park, Presenter: Nothing to Disclose

Boo-Kyung Han MD, PhD, Abstract Co-Author: Nothing to Disclose

Eun Sook Ko MD, Abstract Co-Author: Nothing to Disclose

Eun Young Ko MD, PhD, Abstract Co-Author: Nothing to Disclose

Soo Yeon Hahn MD, Abstract Co-Author: Nothing to Disclose

To evaluate the difference of the incidence and the probability of malignancy of MRI-detected additional suspicious lesions in breast cancer patients according to the molecular subtype of index tumor. .

584 patients with breast cancer undergoing preoperative MRI were included in this study. Two radiologists reviewed their MRI findings and identified MRI-detected additional suspicious lesions. MRI-detected additional suspicious lesions were defined as the lesions seen only on MRI assessed more than BI-RADS category 4 (mammographically, sonographically and clinically occult). We reviewed MRI findings (mass or non-mass enhancement) and the pathologic outcomes of these lesions. According to the estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status of index tumor, we divided the patients into 4 groups; ER+/ HER2-, ER+/ HER2+, ER-/ HER2+, and triple-negative group. We compared the incidence and pathologic outcomes of additional suspicious lesions and the positive predictive value (PPV) of MRI among each group.

Among 584 patients, 129 (22.1%) had additional suspicious lesions on MRI. Of these, 80 (13.7%) lesions were malignant. In terms of molecular subtypes, there were ER+/ HER2- breast cancer in 342 (58.3%), ER+/ HER2+ breast cancer in 114 (19.5%), ER-/ HER2+ breast cancer in 66 (11.3%), and triple-negative breast cancer in 62 (10.6%). On MRI, 72 lesions were masses (33; benign, 39; malignant), and 57 were non-mass enhancement (16; benign, 41; malignant). In triple-negative breast cancers, the malignancy rate of additional suspicious lesions was significantly lower in triple-negative breast cancer group than other groups (p=0.025) whereas the incidence of the MRI-detected additional suspicious lesions was not significantly different (p=0.066) compared with other molecular subtypes. PPV of MRI assessment did not show significant difference according to molecular subtypes (p = 0.266).

Although the incidence of MRI-detected additional suspicious lesion was similar according to molecular subtypes of index tumors, the malignancy rate of additional suspicious lesions on MRI was lower in triple-negative breast cancers.

Little is known about malignancy rate of MRI-detected additional suspicious lesion in breast cancer patients according to molecular subtype.

Park, S, Han, B, Ko, E, Ko, E, Hahn, S, MRI-Detected Additional Suspicious Lesions in Breast Cancer Patients: Probability of Malignancy according to Molecular Subtypes of Index Tumors.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13044334.html