Long-term cardiac mortality following radiation therapy for Hodgkin's disease: analysis with the relative seriality model

Purpose: (a) To assess the increased risk of death due to ischemic heart disease (IHD) in a group of patients treated for Hodgkin's disease (HD) with radiation therapy (RT) as the primary treatment. (b) To quantify the dose response of IHD using a biophysical model. Materials and methods: Patient material consisted of 157 patients diagnosed for HD between 1972 and 1985 who received RT as the primary treatment at Radiumhemmet, Karolinska Hospital. The general population formed the control group. The RT treatments were reconstructed based on the individual treatment data and simulator films. Individual clinical and dosimetrical data were analyzed with the relative seriality model. The material was also analyzed grouping the material according to dose-volume constraints. Results: Of the 157 patients, 13 (8.3%) died due to IHD. The standardized mortality ratio (SMR) was 5.0 (95% CI, 2.7-8.6). Analysis of dose-volume histograms (DVH) showed an increasing risk with increasing dose to a larger volume fraction. The observed individual clinical complication data could not be modeled unambiguously. The group analysis resulted in the dose-response parameters: D-50 = 71 Gy, gamma = 0.96 and s = 1.0. Conclusions: A significantly increased risk of death due to IHD following RT for HD was found. The risk was found to increase with higher dose and larger volume fraction irradiated. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.