Mediastinal irradiation in combined modality therapy for Hodgkin's disease

Patients with Hodgkin's disease who present with large mediastinal masses in the setting of either early or advanced stage disease are frequently treated with combined modality therapy. Policies for radiation dose to the mediastinum in these settings range from no radiation to doses in the 3600-4000 cGy range. We reviewed the charts of 50 patients treated with radiation therapy following remission induction with chemotherapy between 1979 and 1983 to determine whether the dose of radiation to the mediastinum could be correlated with mediastinal control, relapse-free, and overall survival. Patients were divided into groups with small (SM, 30 pts.) and large (LM, 20 pts.) mediastinal masses and analyzed according to whether they had received low dose (LD, less than or equal to 2500 cGy) or high dose (HD, greater than 2500 cGy) radiation to the mediastinum. The 5-year relapse-free survival (RFS) for all 50 patients was 84% (+/- 8%, 95% confidence limits). For the patients with small mediastinal masses, 5-year RFS was 81% +/- 20%, and for the patients with large mediastinal masses, 89% +/- 16%. No clear dose-response effect was observed when the outcomes of the low dose and high dose patients were compared. This was true even in the patients with large mediastinal masses although the high dose subset of this group included patients felt to be at a higher risk for relapse following chemotherapy. Nine of eleven patients with large mediastinal masses treated with chemotherapy and low dose radiation remain disease-free. There was only one isolated mediastinal relapse in the entire group of patients. Treatment was well tolerated with no acute treatment-related deaths. Two patients developed second malignancies. We conclude that combined modality therapy using low dose radiation results in excellent 5-year relapse-free survival for most small and many large mediastinal mass patients, and that it is not necessary to treat all chemotherapy patients who present with mediastinal disease with high dose radiation to achieve these relapse-free survival rates.