Brain metastasis from differentiated thyroid cancer in patients treated with radioiodine for bone and lung lesions

Brain metastasis of differentiated thyroid cancer (DTC) often is detected d uring treatment of other remote lesions. We examined the prevalence, risk f actors and treatment outcome of this disease encountered during nuclear med icine practice. Of the 167 patients with metastasis to lung or bone treated 1-14 times with radioactive iodine (RAI), 9 (5.4%) also had lesions in the brain. Five were males and 4 females, aged 49-84, out of the original popu lation of 49 males and 118 females aged 10-84 (mean 54.7) years. Three of t hem underwent removal of their brain tumors, 5 received conventional extern al beam irradiation, and 2 had stereotactic radiosurgery with supervoltage Xray. None of the brain lesions showed significant uptake of RAI despite de monstrable accumulation in most extracerebral lesions. Seven patients died 4-23 (mean 9.4) months after the discovery of cerebral metastasis, brain da mage being the primary or at least a contributing cause. The gth and 9th pa tients remained relatively well for more than 42 and 3 months, respectively , without any evidence of intracranial recurrence. Our results confirmed th at the brain is a major site of secondary metastasis from DTC. No statistic ally significant demographic risk factor was detected. Any suspicious neuro logical symptoms in the course of RAI treatment warrant cerebral computed t omography. As for therapy, from our initial experience, radiosurgery seemed promising as an effective and less invasive alternative to surgical remova l.