Therapy monitoring of neoadjuvant chemo-/radiotherapy

Background: Neoadjuvant therapy (NAT) is used in particular to reduce the size of tumors and improve resectability. Imaging techniques are fundamental for the assessment of tumor response to therapy.Objectives: This review provides a brief overview of recent developments in NAT and summarizes basic principles of monitoring NAT by imaging.Materials and methods: A team of authors from various oncology-oriented junior groups of German medical societies conducted a structured literature search, supplemented by information from relevant guidelines or consensus papers. Characteristic imaging examples from the involved hospitals were included.Results: In addition to classical concepts of NAT, the adoption of multimodal treatment concepts including targeted therapies is on the rise. Here, adequate treatment response assessment plays an essential role, not least because surgery could be avoided in case of complete remission. Computed tomography (CT) and magnetic resonance imaging (MRI) are widely available as established imaging modalities in oncology and remain the gold standard, but also have their limitations. Functional nuclear medicine imaging using positron emission tomography (PET) is an important adjunct to radiological imaging and is already widely used, usually as hybrid PET/CT.Conclusions: Adequate imaging has a key role in monitoring neoadjuvant chemo-/radiotherapy. More and especially prospective multicenter studies are needed to substantiate the value of the different imaging modalities for NAT with further evidence.