Brian Jin MD, Presenter: Nothing to Disclose

Richard S. Ha MD, Abstract Co-Author: Nothing to Disclose

Victoria Mango MD, Abstract Co-Author: Nothing to Disclose

Lauren C. Friedlander MD, Abstract Co-Author: Nothing to Disclose

Sharp F. Malak MD, MPH, Abstract Co-Author: Nothing to Disclose

Vesselin Miloushev MD, PhD, Abstract Co-Author: Nothing to Disclose

Ralph Thomas Wynn MD, Abstract Co-Author: Nothing to Disclose

Ki-67 proliferative marker and molecular subtypes of breast cancer are known prognostic indicators. This information may assist in clinical staging and treatment planning by predicting patients most likely to have additional disease on pre-operative breast MRI.

A HIPAA compliant IRB waived retrospective review of our database from 1/2010 to 12/2013 identified 299 patients who underwent pre-operative breast MRI with tumors classifiable into molecular subtypes and 198 patients that had Ki-67 values. Subtypes were classified by IHC surrogates as luminal A (ER and/or PR+ , HER2-), luminal B (ER and/or PR+, HER2+), HER2 (ER and PR-, HER2+) or basal (ER, PR, HER2-). Ki-67 index was classified as high (>=15% positive cancer nuclei) or low (< 15%). Univariate and multivariate logistic regression analyses were used to determine associations between subtype, Ki-67 index and additional breast MRI findings including multicentric/multifocal disease (MCD/MFD), contralateral disease, chest wall involvement, skin/nipple involvement and internal mammary and axillary lymphadenopathy.

The subtype distribution was luminal A, 71% (211/299); luminal B, 14.1% (42/299); HER2, 5.4% (16/299); and basal, 10% (30/299). 54% (107/198) of the tumors had a high Ki 67 index and 46% (91/198) a low Ki-67 index. HER2 and luminal B subtypes showed more MCD (31.3% and 28.7%), MFD (37.5% and 38.1% ) and axillary disease (62.5 and 45.2%) compared to luminal A cancers (MCD (10.9%), MFD (23.2%) and axillary disease (17.1%))(P < 0.001). On multivariate analysis, after controlling for patient age, tumor size and nuclear grade, HER2 overexpressing tumors (luminal B and HER2 subtypes) were 3.4 times more likely to have MCD (P<0.0006), 2.0 times more likely to have MFD (P < 0.0255), 4.9 times more likely to have skin/nipple involvement (P<0.0013) and 5.0 times more likely to have axillary disease (P<0.0001) compared with luminal A tumors. High Ki-67 index tumors were 3.9 times more likely to have axillary disease (P<0.0002) compared with low Ki-67 tumors.

Breast cancer disease extent differs among molecular subtypes and between Ki-67 indices. Pre-operative MRI is most useful for clinical staging and treatment planning in patients with tumors with HER2 overexpression and a high K-67 index.

Breast cancer molecular subtypes and Ki-67 index can help identify patients most likely to benefit from pre-operative breast MRI

Jin, B, Ha, R, Mango, V, Friedlander, L, Malak, S, Miloushev, V, Wynn, R, Can Ki-67 Proliferative Marker and Breast Cancer Molecular Subtypes Predict which Patients would Benefit most from Pre-operative Breast MRI?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14015870.html