Total dose, fraction size, and tumor volume in the local control of Hodgkin's disease

There are important uncertainties in the radiation therapy of Hodgkin's disease. These uncertainties are related to dose-fractionation and total dose necessary to control subclinical disease (prophylactic irradiation), small-size tumors, and especially bulky tumors such as those frequently encountered in the mediastinum. Data are lacking on total dose and tumor control as a function of tumor volume. A retrospective study was undertaken of patients with Hodgkin's disease Stages I-III treated with radiation therapy alone at the Medical College of Wisconsin Affiliated Hospitals between 1970 and 1982. Detailed dose calculations of off axis points were made to assign precise minimum doses to 1,304 separate lymph node regions. Treatment volumes received individual fractions of 150 cGy to 300 cGy and total doses of 30 Gy to 42 Gy. Tumor control was correlated with tumor size at presentation, fractionation schedule, and total dose. The results confirm the absence of a dose-response relationship for tumor control, between 30 Gy and 42 Gy total dose. In addition, there is no apparent difference in total dose required for larger tumors relative to that required for small tumors.