Spleen Glucose Metabolism on [18F]-FDG PET/CT for Cancer Drug Discovery and Development cannot be Overlooked

Background: Fluorine-18-fluorodeoxyglucose ([18F]-FDG) Positron Emission Tomography/ Computed Tomography (PET/CT) is a useful tool that assesses glucose metabolism in tumor cells to help guide the management of cancer patients. However, the clinical relevance of glucose metabolism in healthy tissues, including hematopoietic tissues such as the spleen, has been potentially overlooked. Recent studies suggested that spleen glucose metabolism could improve the management of different cancers. Study Eligibility Criteria: Overall, the current literature includes 1,157 patients, with a wide range of tumor types. The prognostic and/or predictive value of spleen metabolism has been demonstrated in a broad spectrum of therapies, including surgery and systemic cancer therapies. Most of these studies showed that high spleen glucose metabolism at baseline is associated with a poor outcome while treatment-induce change in spleen glucose metabolism is a multi-faceted surrogate of cancer- related inflammation, which correlates with immunosuppressive tumor microenvironment as well as with immune activation. Conclusion: In this systematic review, we seek to unravel the prognostic/predictive significance of spleen glucose metabolism on [18F]-FDG PET/CT and discuss how it could potentially guide cancer patient management in the future.