Circulating tumor cells and tumor-derived extracellular vesicles as biomarkers for prostate cancer

Prostate cancer is the most prevalent cancer among men, with approximately 1.4 million diagnoses reported worldwide in the year 2020. Although most patients are diagnosed with localized disease, about 25 % are diagnosed with metastasis with poor outcomes. Despite advances in treatment options, treatment outcomes vary widely due to tumor heterogeneity in patients. This underscores the need for biomarkers to evaluate tumor heterogeneity in patients and eventually ascertain which patients are likely to respond to therapy. In recent years, liquid biopsy has emerged as an attractive alternative to tissue biopsies, offering minimally invasive means to monitor the treatment responses of patients and explore tumor heterogeneity. In this thesis, we primarily focus on circulating tumor cells (CTC) as the main biomarker, while also highlighting how the inclusion of tumor-derived extracellular vesicles (tdEV) enhances our understanding of tumor heterogeneity in metastatic prostate cancer.