Systemic hemibody irradiation for overt and occult metastases

Hemibody irradiation was initially employed as a palliative technique to treat diffuse metastatic disease in one session as opposed to multiple fields over an extended period. It provides a radiation treatment for disseminated cancer and therefore has been termed "systemic" therapy. Since it is possible to treat both halves of the body sequentially, it allows radiation treatment to the whole body in larger doses than could be accomplished with total-body irradiation. Because of the success in terms of dramatic rapid pain relief and the objective response on metastatic disease, it has been explored in the treatment of occult disease and as consolidation therapy in patients with tumors that have responded to chemotherapy. When hemibody irradiation is combined with chemotherapy, responses have been shown in metastases for several primaries, particularly small cell carcinoma, which is perhaps the most encouraging, and supports further research in the treatment of micrometastatic disease for this tumor type. As the technique moves from its current research phase into more general clinical use, radiation oncologists should become more familiar with the treatment, and the hospitalization originally required may be able to be avoided. An intensive premedication program has been developed to facilitate this. Innovative approaches using radiosensitizers, radioprotectors, hyperthermia, and hyperfractionation are ideas that are starting to be tested and will be further explored in the near future.