Abstract： Extended-field and subtotal nodal radiation therapy (RT),developed in the 1960 s,was first reliably curative treatment for early-stage Hodgkin lymphoma (HL). However, the large volume of normal tissue irradiated resulted in significant delayed toxicity, including cardiac disease and second cancers (SC).The 30-year cumulative incidence of heart disease among adult survivors receiving 40-45 Gy of extended-field or mantle RT is approximately 30 ％; the incidence of SC is similar. How to improve disease control while reducing the toxicity of treatment has been a major objective of HL trials. Contemporary involved-field RT (IFRT) and involved-node RT (INRT) reduces irradiated volumes and produces significant reductions in normal tissue dose, and response-adapted therapy may be a means of identifying those patients most likely to benefit from treatment reduction or intensification, and enhanced screening will facilitate early intervention to reduce the clinical burden of late effects. There is a increasing interest in elucidating the genetic correlation of treatment toxicity.