Response assessment in lymphoma

The lymphomas are a heterogeneous group of malignant diseases. They are divided into two broad groups: Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL). Patients suffering from HD and NHL can be cured by appropriate chemotherapy and/or radiotherapy. Accurate staging and response assessment is essential to guide management decisions. The International Workshop Group (IWG) criteria, published in 1999, have become the widely accepted standard for response assessment in NHL. Although the IWG criteria have proved extremely useful in the standardization of treatment response, they do have a number of limitations. As a consequence of this, together with advances in functional imaging, revised criteria have been published recently. The aim of this review is to describe the evidence supporting the available imaging techniques, the limitations of each technique, and how these should be applied in clinical practice. We briefly review the corresponding response criteria for central nervous system (CNS) lymphomas, and take a look at novel imaging techniques that may play a role in the future.