The role of PET in Hodgkin's lymphoma and its impact on radiation oncology.

A high negative-predictive value of (18)F-fluorodeoxyglucose (FDG) PET in early and late response assessment of Hodgkin's lymphoma patients has been observed in numerous trials. The consequent substantial reduction in the number of chemotherapy cycles and radiotherapy in many current trials seems to be very promising. The criteria used to describe (18)F-FDG accumulation are widely standardized, but PET interpretation in a dedicated clinical algorithm is being discussed among study groups and will be evaluated in the ongoing trials. The integration of (18)F-FDG PET into radiation treatment planning could have a substantial impact on treatment volumes within the new target definition 'involved-node radiotherapy'. Involved-node radiotherapy has been proposed as a means to further improve the therapeutic ratio by reducing the risk of acute radiation-induced toxicity and potentially lowering the rate of long-term complications, including secondary malignancies.