One of the methods widely used to measure the proliferative activity of cells in breast cancer patients is the
immunohistochemical (IHC) measurement of the percentage of cells stained for nuclear antigen Ki-67. Use of Ki-67
expression as a prognostic marker is still under investigation. However, numerous clinical studies have reported an
association between a high Ki-67 and overall survival (OS) and disease free survival (DFS). On the other hand, to offer
non-invasive alternative in determining Ki-67 expression, researchers have made recent attempts to study the association
of Ki-67 expression with magnetic resonance (MR) imaging features of breast cancer in small cohorts (<30). Here, we
present a large scale evaluation of the relationship between imaging features and Ki-67 score as: (a) we used a set of 450
invasive breast cancer patients, (b) we extracted a set of 529 imaging features of shape and enhancement from breast,
tumor and fibroglandular tissue of the patients, (c) used a subset of patients as the training set to select features and
trained a multivariate logistic regression model to predict high versus low Ki-67 values, and (d) we validated the
performance of the trained model in an independent test set using the area-under the receiver operating characteristics
(ROC) curve (AUC) of the values predicted. Our model was able to predict high versus low Ki-67 in the test set with an
AUC of 0.67 (95% CI: 0.58-0.75, p<1.1e-04). Thus, a moderate strength of association of Ki-67 values and MRextracted
imaging features was demonstrated in our experiments.
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