An updated dose-response analysis in Hodgkin's disease

Although radiotherapy cures a very high percentage of early stage patients with Hodgkin's disease (HD), there is a controversial dichotomy in the dose recommendations believed necessary to achieve >95% local control: Whereas one school of thought is to administer 40-44 Gy, other reports claim equal results with about 36 Gy. It is also not clear what doses are required for various tumor cell burdens. The original recommendation of 40-44 Gy was derived from a retrospective analysis of in-field control of disease from mostly kilovoltage data 3 decades ago. However, there have been many advances in evaluation of the extent of the disease and in radiotherapy-practice since the 1960s. Many more dose-control studies have been published in recent years, necessitating a revisit to the dose-response question in HD. Here dose-control data from the 60s to the 90s are compiled, and the original and updated data are analyzed with the same statistical method to see any differences. Also was performed a similar analysis of dose-control information for subclinical disease, <6 cm and >6 cm disease. Whereas original analysis (1040 sites at risk) suggested 98% in-field control with 44 Gy, the re- analysis including modern megavoltage data (4117 sites at risk) shows that similar in-field control for subclinical disease and disease of <6 cm and >6 cm are, 32.4 Gy (1426 sites at risk), 36.9Gy (1005 sites at risk) and 37.4 Gy (98 sites at risk), respectively. Results of current updated analysis will provide in-field disease control probabilities for different disease burdens and can serve as a guide in deciding dose prescriptions for practising radiation oncologists. (author). 59 refs.; 3 figs.; 6 tabs