Abstract
Breast cancer is the most commonly diagnosed cancer type and the leading cause of cancer-related mortality in women worldwide. Breast cancer is fairly heterogeneous and reveals six molecular subtypes: luminal A, luminal B, HER2+, basal-like subtype (ER−, PR−, and HER2−), normal breast-like, and claudin-low. Breast cancer screening and early diagnosis play critical roles in improving therapeutic outcomes and prognosis. Mammography is currently the main commercially available detection method for breast cancer; however, it has numerous limitations. Therefore, reliable noninvasive diagnostic and prognostic biomarkers are required. Biomarkers used in cancer range from macromolecules, such as DNA, RNA, and proteins, to whole cells. Biomarkers for cancer risk, diagnosis, proliferation, metastasis, drug resistance, and prognosis have been identified in breast cancer. In addition, there is currently a greater demand for personalized or precise treatments; moreover, the identification of novel biomarkers to further the development of new drugs is urgently needed. In this review, we summarize and focus on the recent discoveries of promising macromolecules and cell-based biomarkers for the diagnosis and prognosis of breast cancer and provide implications for therapeutic strategies.
Highlights
Breast cancer is the most commonly diagnosed cancer type and the leading cause of cancer-related mortality in women worldwide [1]
The phase I JAVELIN study was conducted in patients with metastatic breast cancer who were treated with avelumab, an anti-PD-L1 antibody, and the results showed that the overall response rate (ORR)
A phase I trial intended to target mTOR— and which involved metastatic metaplastic breast cancer treated with liposomal doxorubicin (D) and bevacizumab (A), with either temsirolimus (T) or everolimus (E) (DAT/DAE)—revealed that patients with advanced metaplastic breast cancer treated with mTOR-based systemic therapy had better long-term outcomes than those with nonmetaplastic Triple-negative breast cancer (TNBC), indicating that metaplastic histology may benefit from drugs targeting the PI3K/Akt/mTOR pathway [259]
Summary
Breast cancer is the most commonly diagnosed cancer type and the leading cause of cancer-related mortality in women worldwide [1]. Biomarkers are objective and quantifiable evaluations of biological states or diseases that can predict tumor behavior, prognosis, or treatment responses, playing an important role in the management of breast cancer [18,19] They must be validated by human samples to ensure that they reflect the clinical outcome [20,21]. With the rapid advancement of molecular signaling pathways and genetic signatures, including immunohistochemistry, next-generation sequencing, and targeted multigene, numerous clinically relevant biomarkers in tissue and/or blood (liquid biopsies) have been reported to aid in determining the risk of metastasis, prognosis, recurrence, treatment guidance, and drug resistance in breast cancer. We summarize and focus on the recent discovery of promising biomarkers for the diagnosis and prognosis of breast cancer and provide their implications in therapeutic strategies
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