Can proton MRS provide useful information for characterizing estrogen receptor status in breast cancer?

Estrogen receptor (ER) status has been used in the clinical management of breast cancer both as a predictive factor for treatment and as a prognostic factor for survival [1]. Compared with ER-positive cancer, ER-negative cancer has a poorer clinical outcome and shorter median survival [2–3]. ER-negative cancer was more aggressive, with bigger tumor size, more prominent tumor infiltration showing non-mass type enhancements on magnetic resonance imaging (MRI) features [4]. ER-negative tumors showed higher intratumoral microvessel density than did ER-positive tumors [5]. ER-negative breast carcinoma was also associated with an increased choline kinase (ChoK) activity [6]. The ChoK and its product, phosphocholine (PCho), have been implicated in human carcinogenesis. Elevated level of total choline-containing compounds (tCho) is a tissue proliferative marker for malignant tumor [7]. In this study, we reported a quantitative proton magnetic resonance spectroscopy (1H-MRS) study to further investigate if the tCho level shows difference between ER-positive and ER-negative breast cancers. The aim of our study was to determine whether in vivo 1H-MRS can provide useful information for characterizing ER status in breast cancer. Forty-seven breast cancer patients, who were scanned with the MRI/proton magnetic resonance spectroscopy (MRS) protocol from June 2004 to December 2006, were included in this study. The inclusion criteria were patients with biopsy confirmed diagnosis of malignant lesions that measured ≥1.8 cm on magnetic resonance (MR) images. All 47 patients had histopathologically an invasive ductal carcinoma. The ER status was examined by pathologists at hospital and was considered negative if immunoperoxidase staining of tumor cell nuclei in the biopsy specimen was