Historically, treatment algorithms were designed to determine which patients could be cured with radiation therapy alone and which patients had a poor prognosis with radiation therapy and required combination chemotherapy. This is why staging laparotomies evolved: if one could prove that a patient had no pathologic evidence of disease below the diaphram, then one might save the patient from the toxicity of combination chemotherapy and successfully treat the patient with radiation alone. There were many reasons for this treatment strategy. Extended field radiation therapy was successful, with the majority of patients with stage I and II HL being cured. In the 1970s and 1980s, acute toxicities from combination chemotherapy were significant. Antiemetic therapy was poor; the use of MOPP (mechlorethamine, oncovin (vincristine), procarbazine, and prednisone) combination chemotherapy had a known leuke-mogenic risk; issues of sterility were a genuine concern; and the risk of neutropenic fever and serious infections were clinically important, especially in the era prior to the availability of hematopoietic growth factors. Additionally, it was commonly felt that if patients progressed after radiation therapy, the majority could be successfully salvaged at a later date with combination chemotherapy. Thus, a 25-30% incidence of relapse after radiation therapy was deemed to be less significant because of later successful salvage with combination chemotherapy. As a result, radiation therapy continues to this day to be a primary treatment modality for limited stage HL.

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