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Determining hormone receptor expression is a key part of breast cancer evaluation.
Estrogen receptor (ER) and progesterone receptor (PR) status provide good prognostic value, although at present the greatest clinical value of determining receptor status is in assessing the likelihood that a patient will respond to hormone therapies (predictive value), both in early and advanced stages of the disease.¹
Currently, it is the most common subtype. Hormone receptors are found at the intracellular level and their presence or absence is diagnosed through tissue analysis, using immunohistochemistry. When these receptors are present, and when female hormones bind to them, cell growth occurs, in this case, tumor cells. Estrogen and progesterone receptor expression enable the identification of patients who will benefit from hormone therapy, as both an adjuvant therapy and in metastatic disease.²
What does Ki67 mean?
Ki67 is a nuclear protein associated with cell growth. Its level is determined by tissue analysis using immunohistochemistry. Its use in isolation is not recommended for decision-making in daily practice, but it is an indicator of cell proliferation that many clinicians find useful in association with other prognostic and predictive factors when making treatment decisions.³*
What does HER2-positive mean?
A HER2-positive test indicates that the patient’s breast cancer cells are producing an excessive amount of the HER2 protein and are overexpressing it. A cell in HER2-positive cancer has about 100 times more HER2 protein than a normal cell.
The two types of tests used to determine HER2-positive breast cancer are called immunohistochemistry (IHC) and in situ hybridization (ISH).
The IHC test shows the amount of HER2 protein present in the tumor sample. The ISH test measures the amount of the gene responsible for the excessive production of HER2 protein, which can be visualized by fluorescence (FISH) or a chromogenic reaction with a silver (SISH).
Diagnosis of Breast Cancer. Original article published at https://www.rochecercatuyo.com.ar/cancer-de-mama-diagnostico, accessed last May 2022.
References:
- Hormone receptor status. Accessed at https://www.breastcancer.org/pathology-report/hormone-receptor-status, last accessed on May 2022.
- Roche Institute. Accessed at https://www.institutoroche.es/oncobyg/marcadoresmoleculares/cancer_de_mama/rutinarios/1/#info_marcador, last accessed on May 2022.
- Yerushalmi, Rinat, et al. “Ki67 in breast cancer: prognostic and predictive potential.” The Lancet. Oncology vol. 11,2: 174-83. doi:10.1016/S1470-2045(09)70262-1, 2010.
- Ki67 is analyzed together with other proliferation markers. According to the American Society of Clinical Oncology (ASCO) guidelines, they should not be used for decision-making. Andre, Fabrice, et al. “Biomarkers for Adjuvant Endocrine and Chemotherapy in Early-Stage Breast Cancer: ASCO Guideline Update.” Journal of clinical oncology: official journal of the American Society of Clinical Oncology, JCO2200069. 19 Apr. 2022.