Breast cancer is the most common cancer among women, with hormone receptors playing a crucial role, not only in cancer cell growth but also as primary targets in breast cancer treatment.
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Breast cancer is the most common cancer among women, with hormone receptors playing a crucial role, not only in cancer cell growth but also as primary targets in breast cancer treatment. This systematic literature review aimed to summarize the current evidence on estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) discordance rates between primary and recurrent breast cancer. Additionally, it seeks to identify how discordance affects prognosis, metastasis, and the potential evidence of primary tumor heterogeneity.
The databases Web of Science, Scopus, MEDLINE, and PubMed were searched for publications of original research in English from 2013 to 2023. Studies with paired histopathology from primary and recurrent breast cancer that employed immunohistochemistry and fluorescence in situ hybridization were included. Ten studies were deemed eligible for inclusion.
Concordance between primary and recurrent breast cancer was high for ER (80%), PR (65%), and HER2 (85%). Average discordance rates were: ER 19%, PR 34%, and HER2 15%, with PR discordance consistently being the highest. Loss of ER and PR receptors was observed more frequently than gain, while the opposite trend was noted for HER2. Loss of ER and PR was associated with a worse prognosis. Discordance was also observed in cases of tumor metastasis.
Discordance in receptor expression between primary and recurrent breast cancer was common, highlighting the importance of re-biopsy in recurrent or metastatic breast cancer, if possible. Patients who lost hormone receptors experienced worse outcomes, suggesting the development of treatment-resistant tumor clones.
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