The Diversity of Liquid Biopsies and Their Potential in Breast Cancer Management

Liquid biopsy biomarkers in breast cancer: An overview of systematic reviews

Breast cancer (BC) is the leading type of cancer affecting women globally and remains a significant cause of death. The diagnostic accuracy of liquid biopsy (LB) in the diagnosis of BC has not been well established. This overview synthesizes and critically evaluates the diagnostic test accuracy (DTA) of LB biomarkers in individuals with BC. Of 433 systematic reviews, eleven were included, assessing Fourier transform infrared (FTIR) spectroscopy, circulating tumor cells (CTCs), cell-free DNA (cfDNA), and microRNAs (miRNAs). The overall methodological quality of most of the reviews included was rated as critically low (n = 9, 81.8 %), and the remaining reviews were ranked as low and moderate. Key findings include CTCs with moderate sensitivity (0.50, 95 % confidence interval (CI) 0.48-0.52) and high specificity (0.93, 95 % CI: 0.92-0.95) with moderate certainty; cfDNA assays with high sensitivity (0.71-0.86) and specificity (0.88) with high certainty; FTIR assays with high sensitivity (0.97, 95 % CI: 0.94-0.96) and specificity (0.92, 95 % CI: 0.88-0.95) but low certainty. The miRNAs showed moderate to high sensitivity, while miR-21 had high specificity. Our overview indicates that identified liquid biopsies could serve as valuable tools for the diagnosis of breast cancer.

Circulating Tumor DNA in Early and Metastatic Breast Cance-Current Role and What Is Coming Next

The progress that has been made in recent years in relation to liquid biopsies in general and circulating tumor DNA (ctDNA) in particular can be seen as groundbreaking for the future of breast cancer treatment, monitoring and early detection. Cell-free DNA (cfDNA) consists of circulating DNA fragments released by various cell types into the bloodstream. A portion of this cfDNA, known as ctDNA, originates from malignant cells and carries specific genetic mutations. Analysis of ctDNA provides a minimally invasive method for diagnosis, monitoring response to therapy, and detecting the emergence of resistance. Several methods are available for the analysis of ctDNA, each with distinct advantages and limitations. Quantitative polymerase chain reaction is a well-established technique widely used due to its high sensitivity and specificity, particularly for detecting known mutations. In addition to the detection of individual mutations, multigene analyses were developed that could detect several mutations at once, including rarer mutations. These methods are complementary and can be used strategically depending on the clinical question. In the context of metastatic breast cancer, ctDNA holds particular promise as it allows for the dynamic monitoring of tumor evolution. Through ctDNA analysis, mutations in the ESR1 or PIK3CA genes, which are associated with therapy resistance, can be identified. This enables the early adjustment of treatment and has the potential to significantly enhance clinical outcome. The application of ctDNA in early breast cancer is an ongoing investigation. In (neo)adjuvant settings, there is preliminary data indicating that ctDNA can be used for therapy monitoring and risk stratification to decide on post-neoadjuvant strategies. In the monitoring of aftercare, the detection of ctDNA appears to be several months ahead of routine imaging. However, the feasibility of implementing this approach in a clinical setting remains to be seen. While the use of ctDNA as a screening method for the asymptomatic population would be highly advantageous due to its minimally invasive nature, the available data on its clinical benefit are still insufficient. Nevertheless, ctDNA represents the most promising avenue for fulfilling this potential future need.

Modeling the management of patients with human epidermal growth factor receptor 2-positive breast cancer with liquid biopsy: the future of precision medicine

PURPOSE OF REVIEW

In the evolving landscape of human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) management, liquid biopsy offers unprecedented opportunities for guiding clinical decisions. Here, we review the most recent findings on liquid biopsy applications in HER2-positive BC and its potential role in addressing challenges specific to this BC subtype.

RECENT FINDINGS

Recent studies have highlighted the significance of liquid biopsy analytes, primarily circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs), in stratifying patients' prognosis, predicting treatment response, and monitoring tumor evolution in both early and advanced stages of BC. Liquid biopsy holds promise in studying minimal residual disease to detect and potentially treat disease recurrence before it manifests clinically. Additionally, liquid biopsy may have significant implication in the management of brain metastasis, a major challenge in HER2-positive BC, and could redefine parameters for determining HER2 positivity. Combining ctDNA and CTCs is crucial for a comprehensive understanding of HER2-positive tumors, as they provide complementary insights.

SUMMARY

Research efforts are needed to address analytical challenges, validate, and broaden the application of liquid biopsy in HER2-positive BC. This effort will ultimately facilitate its integration into clinical practice, optimizing the care of patients with HER2-positive tumors.

Standardized molecular pathology workflow for ctDNA-based ESR1 testing in HR+/HER2- metastatic breast cancer

Mutations in the estrogen receptor alpha gene (ESR1) can lead to resistance to endocrine therapy (ET) in hormone receptor-positive (HR+)/ HER2- metastatic breast cancer (MBC). ESR1 mutations can be detected in up to 40 % of patients pretreated with ET in circulating tumor DNA (ctDNA). Data from prospective randomized trials highlight those patients with HR+/HER2- MBC with detectable ESR1 mutations experience better outcomes when receiving novel selective estrogen receptor degraders (SERDs). There is a high need for optimizing ESR1 testing strategies on liquid biopsy samples in HR+/HER2- MBC, including a hugh quality workflow implementation and molecular pathology reporting standardization. Our manuscript aims to elucidate the clinical and biological rationale for ESR1 testing in MBC, while critically examining the currently available guidelines and recommendations for this specific type of molecular testing on ctDNA. The objective will extend to the critical aspects of harmonization and standardization, specifically focusing on the pathology laboratory workflow. Finally, we propose a clear and comprehensive model for reporting ESR1 testing results on ctDNA in HR+/HER2- MBC.

Circulating tumor cells et al.: towards a comprehensive liquid biopsy approach in breast cancer

Liquid biopsy has emerged as a crucial tool in managing breast cancer (BC) patients, offering a minimally invasive approach to detect circulating tumor biomarkers. Until recently, the majority of the studies in BC focused on evaluating a single liquid biopsy analyte, primarily circulating tumor DNA and circulating tumor cells (CTCs). Despite the proven prognostic and predictive value of CTCs, their low abundance when detected using enrichment methods, especially in the early stages, poses a significant challenge. It is becoming evident that combining diverse circulating biomarkers, each representing different facets of tumor biology, has the potential to enhance the management of patients with BC. This article emphasizes the importance of considering these biomarkers as complementary/synergistic rather than competitive, recognizing their ability to contribute to a comprehensive disease profile. The review provides an overview of the clinical significance of simultaneously analyzing CTCs and other biomarkers, including cell-free circulating DNA, extracellular vesicles, non-canonical CTCs, cell-free RNAs, and non-malignant cells. Such a comprehensive liquid biopsy approach holds promise not only in BC but also in other cancer types, offering opportunities for early detection, prognostication, and therapy monitoring. However, addressing associated challenges, such as refining detection methods and establishing standardized protocols, is crucial for realizing the full potential of liquid biopsy in transforming our understanding and approach to BC. As the field evolves, collaborative efforts will be instrumental in unlocking the revolutionary impact of liquid biopsy in BC research and management.

Research progress of CTC, ctDNA, and EVs in cancer liquid biopsy

Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and extracellular vehicles (EVs) have received significant attention in recent times as emerging biomarkers and subjects of transformational studies. The three main branches of liquid biopsy have evolved from the three primary tumor liquid biopsy detection targets-CTC, ctDNA, and EVs-each with distinct benefits. CTCs are derived from circulating cancer cells from the original tumor or metastases and may display global features of the tumor. ctDNA has been extensively analyzed and has been used to aid in the diagnosis, treatment, and prognosis of neoplastic diseases. EVs contain tumor-derived material such as DNA, RNA, proteins, lipids, sugar structures, and metabolites. The three provide different detection contents but have strong complementarity to a certain extent. Even though they have already been employed in several clinical trials, the clinical utility of three biomarkers is still being studied, with promising initial findings. This review thoroughly overviews established and emerging technologies for the isolation, characterization, and content detection of CTC, ctDNA, and EVs. Also discussed were the most recent developments in the study of potential liquid biopsy biomarkers for cancer diagnosis, therapeutic monitoring, and prognosis prediction. These included CTC, ctDNA, and EVs. Finally, the potential and challenges of employing liquid biopsy based on CTC, ctDNA, and EVs for precision medicine were evaluated.

Male Breast Cancer: Current Scenario and Future Perspectives

Male breast cancer (MBC), one of the rare types of cancer among men where the global incidence rate is 1.8% of all breast cancers cases with a yearly increase in a pace of 1.1%. Since the last 10 years, the incidence has been increased from 7.2% to 10.3% and the mortality rate was decreased from 11% to 3.8%. Nevertheless, the rate of diagnoses has been expected to be around 2.6% in the near future, still there is a great lack in studies to characterize the MBC including the developed countries. Based on our search, it is evidenced from the literature that the number of risk factors for the cause of MBC are significant, which includes the increase in age, family genetic history, mutations in specific genes due to various environmental impacts, hormonal imbalance and unregulated expression receptors for specific hormones of high levels of estrogen or androgen receptors compared to females. MBCs are broadly classified into ductal and lobular carcinomas with further sub-types, with some of the symptoms including a lump or swelling in the breast, redness of flaky skin in the breast, irritation and nipple discharge that is similar to the female breast cancer (FBC). The most common diagnostic tools currently in use are the ultrasound guided sonography, mammography, and biopsies. Treatment modalities for MBC include surgery, radiotherapy, chemotherapy, hormonal therapy, and targeted therapies. However, the guidelines followed for the diagnosis and treatment modalities of MBC are mostly based on FBC that is due to the lack of prospective studies related to MBC. However, there are distinct clinical and molecular features of MBC, it is a need to develop different clinical methods with more multinational approaches to help oncologist to improve care for MBC patients.