Retreatment of Brain Tumors

The Value of irradiation in the treatment of gliomas and other brain tumors has been well established. In most patients, however, this therapy achieves only palliation, and a permanent cure is produced in but a small minority of cases. Most patients, therefore, present with residual or recurrent symptoms following the initial course of radiotherapy. The physician who is contemplating a repeated course must consider that recurrent symptoms may be due to delayed radiation changes in the brain instead of regrowth of tumor. In tumor reappearance, further radiotherapy may be of value, whereas it is contraindicated if the symptoms are due to previous radiation. If there are signs of increased intracranial pressure, then regrowth of tumor is almost certain. Radioisotope brain scanning, pneumoencephalography, or cerebral angiography can be performed to find evidence of tumor regrowth. In most cases with recurrent symptoms following radiation therapy for brain tumor, the determination of previous doses of radiation could decide whether radionecrosis is the cause of the symptoms. Not all portions of the nervous system have the same radiation tolerance. That of the brain was discussed by Lampe (4) in 1958. He reviewed several pertinent reports and included dosage recommendations based on tolerance of the brain. Boden (1) had earlier recommended maximum doses of 3,600 R in seventeen days with large-field technics and 4,500 R in seventeen days with small fields. Lampe adjusted these doses, using Strandqvist curves, to longer treatment periods; for five weeks the figures were 4,100 R for large fields and 5,300 R for small fields. These figures are for orthovoltage radiation and do not take into consideration the increased radiosensitivity of the brain stem. Moss recommends megavoltage doses of 4,500 rads in five weeks if the brain stem is included, 6,000 rads in six weeks for curative therapy if the brain stem is excluded, and 6,000 to 7,000 rads in six to seven weeks if radiation is limited to the frontal or occipital regions. We were interested in determining how often patients were significantly helped by repeat radiotherapy for recurrent brain tumor symptoms. The charts of all patients who received radiation therapy for brain tumors in 1955–65 were reviewed. Twelve cases were discovered with initial radiotherapy for an intracranial glioma and subsequent retreatment because of recurrent symptoms. The cases are summarized in TABLE I. In those patients treated at the UCLA Center for the Health Sciences the exact same fields were used. In patients who received the initial course of treatment elsewhere, it appears from the records that the ports were essentially the same. The last 3 cases of brain-stem tumor were diagnosed by air studies. In 2 of these, the tumor was also visualized at surgery for insertion of Torkildsen shunts, although no biopsy was obtained.