Interstitial irradiation of brain metastases

Randomized studies have shown that survival in patients with single brain metastases is significantly higher after the combined treatment of surgical removal and whole-brain irradiation than after whole-brain radiation therapy alone. In patients with deep-seated lesions or those located in critical sites of the brain, as well as in cases in which the patient's general condition makes general anaesthesia difficult or impossible microsurgical resection usually cannot be performed or only with an increased surgical risk. Stereotactic radiosurgery, which can be done by means of convergent beam irradiation or by the implantation of highly loaded 125I seeds, provides an alternative to open procedures. In the following we report on our results using a stereotactic radiosurgical technique. A series of 20 treatments is presented, in which biopsy was performed and 125I seeds were implanted, both under stereotactic conditions in the same session. The 125I seeds were sealed in a teflon catheter, were left indwelling temporarily, and then removed after application of the prescribed radiation dose (6,000cGy at the tumour margin). There was only one recurrence in our series, complications occurred in only one patient by temporary aggravation of a pre-existing hemiparesis. Our results indicate that interstitial irradiation of brain metastases is a valuable, less stressful alternative to both open microsurgery as well as to stereotactic radiosurgical convergent beam irradiation.