Nuclear imaging in cancer theranostics.

The combination of a diagnostic test with a therapeutic entity is termed theranostics. The diagnostic test aims at identifying patients who will likely benefit from a specific therapeutic intervention, fail to respond or eventually manifest side effects to a given drug. The appropriate selection of patients for innovative therapies would promote an enrichment of patient population that can potentiate clinical trials and, eventually, accelerate the drug development process. For these reasons, many drug companies adopted a theranostic approach as a new and promising avenue for drug development. From an historical perspective, the concepts underlying the theranostic strategy are well known in nuclear medicine and constituted the basis of many nuclear imaging procedures currently used in clinical practice. Nevertheless the adoption of these concepts by regulatory authorities is a real progress and reflects the remarkable advances in the development of drugs against molecular targets. In this respect, the oncological field provides the strongest evidence of the clinical need to link diagnostics to therapeutics. Here, we review the contribution that non-invasive nuclear imaging may give to cancer theranostics and report prominent examples of nuclear imaging procedures that can be coupled to specific therapies. The main focus lies on imaging procedures that can identify patients who will benefit from molecularly targeted therapy or are going to fail to respond to standard treatment.