The role of radiation therapy for limited stage (I and II) Hodgkin's disease; limitations and perspectives

The role of radiotherapy in limited stage Hodgkin's disease (HD) has been gradually changing in the past few decades resulting in the almost complete disappearance of exclusive irradiation treatment. In reality, exclusive radiotherapy yielded satisfactory results in terms of long-term survival, but in 1999 it was becoming impossible not to take into account the the late mortality rates observed in all large cohorts of HD patients. This increased mortality rate has been shown to be related to: cardiac toxicity of irradiation; secondary radiation-induced solid tumors. Thus, the search for efficient but less toxic new strategies can no longer be avoided. For clinically staged, limited HD, precisely defined according to specific prognostic factors, the association of chemotherapy and radiotherapy appears more and more as a standard, and with this therapeutic burden comes parallel efforts for its alleviation. The Previous Radiotherapy experience has shown that, after a chemotherapy-induced complete remission, irradiation of only the initially involved areas was enough. Ongoing trials are now exploring the possibility of a dose de-escalation, from the conventional 36 Gy to 20 Gy (as for children HD), and to maybe 0 Gy (no radiotherapy at all). In parallel, de-escalation in the number of chemotherapy cycles is also being investigated. For unfavorable cases, the problem is slightly different, as a higher percentage of cases still appears to be refractory to treatment in this subgroup. Thus, while chemo-radiotherapy has clearly became the standard strategy, efforts are essentially being devoted to identify new - and hopefully more efficient - chemotherapy schemes. In Europe, most of these pending questions will be addressed in the recently initiated trials of the EORTC/GELA and of the GHSG (German Hodgkin Study Group), with the aim of offering to patients treatments which could be at least as efficient as the present schedules, and less toxic in the long term. (authors)