ABSTRACT:
Amplification of the human epidermal growth factor receptor 2 (HER-2) oncogene is present in approximately 15% of primary invasive breast cancers and trastuzumab is a monoclonal antibody that targets HER-2. In this case report, we present a case of locally advanced breast carcinoma who lost expression of HER-2 after treatment with trastuzumab and also discuss the clinical implications of this change. A 28 years female presented with complaints of a painful lump in the left breast, measuring 2 x 3 cm firm, mobile, and tender in the outer upper quadrant of the left breast. Core biopsy from a larger lesion revealed invasive ductal carcinoma Grade III. The immuno-histochemical assessment revealed the estrogen receptor
(ER) negative (0%), progesterone receptor (PR) positive (80%) and HER-2 3+ positive. Fluorescent in situ hybridization (FISH) the analysis revealed more than six signals per nucleus with HER-2/CEP-17 signal ratio of more than six confirming HER-2 positivity by FISH. She was treated with neoadjuvant chemotherapy with docetaxel, carboplatin, and trastuzumab for 6 cycles and the disease became metabolically inactive. She underwent left modified radical mastectomy and axillary clearance a month later. Six months postoperatively, she presented with complaints of headache for 20 days. Magnetic Resonance Imaging of brain revealed enhancing T2 heterogeneously hyperintense lesion in the right occipito-parietal lobe with extensive perilesional edema, few foci of susceptibility-weighted imaging
hypointensities with effacement of adjacent sulci, occipital horn, and body of right lateral ventricle and midline shift of 5 mm to the left side was suggestive of metastasis. Additionally, repeat FISH analysis revealed that the patient’s HER-2 status became negative. Our patient had a change in HER2 status pre and post-treatment, which has shown to affect relapse-free survival in patients, as in our case.
Keywords: Breast, Carcinoma, Trastuzumab, Imagin