Uncontrolled cell proliferation is an important hallmark of
cancer.
Cancer treatment with
cytostatic chemodrugs usually results in insignificant changes in
tumor size, and thus limits the applications of anatomical imaging modalities for determining the therapeutic efficacy. Positron emission tomography (PET) imaging with cell proliferation probes to assess the clinical outcome during or soon
after treatment is becoming acceptable. At present, monitoring
DNA synthetic pathways with radiolabeled
nucleoside probes that are essential for cell proliferation has been considered a more specific approach to predict
tumor response. Among the four
nucleosides,
thymidine analogues, such as (18)F-FLT, have undergone years of development for clinical practice, while
cytidine,
adenosine and
guanosine analogues receive less attention. Recently, several literatures have demonstrated that PET imaging with radiolabeled
cytidine and
adenosine analogues may have potential to evaluate immune response after
chemotherapy, and may enable the prognosis forecast. In this review, we summarize the results of recent preclinical and clinical studies regarding using radiolabeled
nucleoside analogues for predicting and monitoring
tumor response in
cancer treatment. The preparation protocols of these
nucleoside scintigraphic probes are also described.