One of the hallmarks of breast cancer is the heterogeneity of its cell populations. This heterogeneity is classified based on its temporal as well as spatial heterogeneity. As tumor progression occurs, cell populations undergo changes in response to various growth factors expressed from the tumor cells as well as changes in response to various treatments to which they are exposed. This change in cell population over time is referred to as a temporal heterogeneity. However, at any given time in the progression of a breast malignancy, malignant cells of various phenotypes are seen and make up the spatial heterogeneity of breast cancer. This variation in phenotype is a result of genetic and epigenetic alterations that occur in clonal populations but can also involve adaptive responses to levels of proteins involved in signaling pathways. These variations in cell populations thus yield variations in the expression of receptors used to target and treat breast malignancies. This accounts for variability in hormone and trastuzumab therapy response between individuals with similar expression levels seen on biopsy; it can also account for the variability in expression between primary and metastatic lesions. However, certain factors help associate metastatic lesions to their original primary.
GATA3 is a zinc-finger binding transcription factor that has been implicated in the differentiation of many tissues, including breast tissue. Previous studies have shown that GATA3 expression in breast tissue is highly specific for carcinoma. In addition, GATA3 is expressed in ER-positive tumors rather than in those that are ER negative. However, studies have shown GATA3 expression is maintained between primary and metastatic lesions.
GATA3 test results of the liver lesions in this patient were positive. This suggests that the malignancy was due to an ER-positive breast carcinoma, like the patient's original carcinoma, rather than an undiagnosed cancer. Unfortunately for the patient in this case, during her workup for the hepatic lesions, she was found to have an obstructing renal calculus that required cystoscopic intervention. She subsequently opted to pursue palliative care.
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Cite this: Nafisa Kuwajerwala, Angad Pordal. A 68-Year-Old Woman With Weight Loss and Abdominal Pain - Medscape - Oct 19, 2018.