The definition of early stages in HL varied among cooperative groups and clinical trials. Most of them considered early stages; stage I, II, and IIIA without bulky disease. Bulky disease has been defined at the Costwolds Meeting as those tumors with more than 10 cm or a mediastinal involvement of more than one-third of the chest wall diameter. Other factors that have been considered unfavorable within the early stages are old age, high ESR, mixed cellularity or lymphocyte depleted histology, B symptoms or multiple sites of disease.