Enhancement parameters on dynamic contrast enhanced breast MRI: do they correlate with prognostic factors and subtypes of breast cancers?

Objective: To correlate the enhancement parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with prognostic factors and immunohistochemical subtypes of breast cancer.

Material and methods: A total of 81 breast carcinomas were included in our study. We obtained the following enhancement parameters: 1) analysis of background parenchymal enhancement (BPE) and BPE coefficients (BEC) from bilateral breasts, 2) the number of vessels per breast as a representation of ipsilateral whole-breast vascularity. Additionally, in 50 patients, 3) semiquantitative parameters of tumors (the initial enhancement percentage (E1), the peak enhancement percentage (Epeak), the time to peak enhancement (TTP), the signal enhancement ratio (SER)) and 4) perfusion parameters (K(trans), kep, ve and iAUC) from tumors and ipsilateral breasts were also obtained. Correlations among parameters and prognostic factors, including tumor size, axillary node status, nuclear grade, histologic grade, estrogen receptor (ER) expression, progesterone receptor (PR) expression, Ki-67, human epidermal growth factor receptor 2 (HER-2) expression, epidermal growth factor receptor (EGFR) expression, bcl-2, CK5/6 and subtypes categorized as luminal (ER or PR positive), triple negative (ER or PR negative, HER-2 negative) and HER2 (ER and PR negative with HER-2 overexpression) were analyzed.

Results: BPE was significantly correlated with EGFR expression (p=0.040). BEC was significantly higher in tumors larger than 2cm than in tumors smaller than 2cm (p=0.001). The vessel numbers in ipsilateral breasts were higher in tumors larger than 2cm than in tumors smaller than 2cm (p=0.034), with higher nuclear grades (grade 3) than with lower nuclear grades (grade 1,2) (p=0.001) and with PR-negative rather than with PR-positive (p=0.010) results. The mean K(trans) was higher in Ki-67-positive tumors than Ki-67 negative tumors (p=0.002). The mean kep was higher in Ki-67-positive tumors than in Ki-67-negative tumors (p=0.005) and in CK5/6-positive tumors than in CK5/6-negative tumors (p=0.015). The mean K(trans) was lower in the ipsilateral breast parenchyma with HER-2-positive tumors compared to HER-2-negative tumors (p=0.012).

Conclusion: BPE, BEC and ipsilateral whole-breast vascularity, higher K(trans) and kep of the cancer and lower K(trans) and iAUC of ipsilateral breast parenchyma may serve as additional predictors of a poor breast cancer prognosis.