PET and SPECT Imaging of Tumor Micro-Environment: A Systematic Review of the Last 20 Years

Background: Molecular nuclear medicine, due to hybrid imaging camera systems and new tailored radiopharmaceuticals, has been gained a clinical relevance for diagnosis, therapy and follow-up of solid tumors. Despite numerous literature studies, many new radiopharmaceuticals for imaging tumor microenvironment, have not yet been used, routinely, in oncological clinical practice to monitor treatments. This is due to poor comparability of published studies, due to poor design and methodology, heterogeneous population and prevalence of preclinical studies. Methods: In this systematic review, we described the use of radiopharmaceuticals for evaluation of tumor treatment response by targeting microenvironment. We reviewed studies published from 2000 to 2020, to provide an updated status of research in this topic. Results: There is a growing role of radiopharmaceuticals and nuclear medicine imaging techniques in the management of cancer treatments, especially immunotherapy. Of the 24 papers included, 16 were preclinical studies. Conclusions: New radiopharmaceuticals could have an excellent impact in molecular imaging, leading to better diagnosis and important clinical information for therapy decision making and follow-up of cancer treatments in different solid tumors. Recently developed radiopharmaceuticals may provide great advantage to improve personalized medicine for patients with a great costeffectiveness ratio.