The Role of Tumor Microenvironment in Cancer Progression: A Pathological Approach to Biomarker Discovery

Background: The tumor microenvironment (TME) plays a crucial role in the progression of various cancers, influencing both tumor growth and therapeutic responses. Comprising multiple cellular components such as cancer-associated fibroblasts (CAFs), immune cells, blood vessels, and the extracellular matrix (ECM). Moreover, therapeutic interventions like chemotherapy and radiotherapy can further modify their composition, potentially affecting treatment outcomes. Aim: This review aims to examine the role of the TME in cancer progression, focusing on its components and the potential of targeted imaging for therapeutic and diagnostic applications. It explores how understanding the TME’s cellular heterogeneity and response to treatment could improve cancer management, particularly through molecular imaging. Methods: We reviewed preclinical and clinical studies that investigated TME-targeted imaging agents, including radiotracers and biomarkers associated with CAFs, cancer stem cells (CSCs), ECM, and immune cells. Various imaging modalities, such as positron emission tomography (PET), magnetic resonance imaging (MRI), and single-photon emission computed tomography (SPECT), were explored for their potential in diagnosing and monitoring cancer progression. Results: Studies identified specific biomarkers such as fibroblast activation protein (FAP) and collagen type I as key targets for imaging TME components. Radiotracers like [68Ga]Ga-FAPI-04 and [68Ga]Ga-FAPI-46 demonstrated improved diagnostic sensitivity and tumor-specific imaging compared to conventional markers like [18F]-FDG. These imaging agents enabled better visualization of TME-related factors. Conclusion: Targeting the TME using advanced imaging techniques holds significant promise for enhancing cancer diagnosis, prognosis, and therapeutic monitoring. The integration of molecular imaging with TME biomarkers offers a path to more personalized and effective cancer treatments.