The value of positron emission tomography in prognosis and response assessment in non-Hodgkin lymphoma.

Positron emission tomography (PET) is widely used for post-treatment response assessment in lymphoma. However, the role of PET in prognosis and early response assessment is still being defined. Studies have shown that PET can identify response early during chemotherapy and that interim PET can predict outcome in diffuse large B-cell lymphoma (DLBCL). Whether the results of early or post-treatment response assessment can be used to determine prognosis and/or guide therapeutic decisions, known as response-adapted therapy, is currently being investigated, with considerable promise in certain lymphomas such as Hodgkin lymphoma (HL) and DLBCL. The use of interim PET is currently limited by a lack of standardized imaging protocols and reporting criteria, and unproven reproducibility of interpretation. As a result, until further data are generated and a consensus reached, interim PET should be considered investigational and applied only within the confines of clinical studies. This review provides an overview of the use of PET for prognosis and response assessment, and in response-adapted therapy. Current limitations of the technique will be summarized, and innovative uses of PET in grading, staging, and surveying lymphomas will be briefly explored.