Brain metastases from differentiated thyroid cancer occurring during and after radioactive iodine therapy: a report of four cases and literature review

Abstract

Background Brain metastases from differentiated thyroid cancer are uncommon, and the prognosis of patients with them is poor. To explore the optimal treatment for this entity, we retrospectively investigated incidence and features of brain metastases from differentiated thyroid cancer that appeared during and after radioactive iodine therapy. Methods Between 2002 and 2012, 89 patients of differentiated thyroid cancer were included (median age, 63-years; male/female = 29/60). The median follow-up time from first ablation was 63 months (range: 1–175 months). The median cumulative radioactive iodine dose was 8.51 GBq (range: 1.11–42.55 GBq). Results During the follow-up, brain metastases occurred in four (4.5 %) patients. The median follow-up time after first ablation of four patients was 69 months (22, 63, 76 and 105 months). They had already had extracranial metastases at first ablation (lung metastases: 3, lung and bone metastases: 1), and had one or more lesions resistant to radioactive iodine therapy at diagnosis of brain metastasis. Three of them had experienced major hemorrhage from brain metastasis. Survival time intervals from the diagnosis to brain metastasis were 2.5, 3.6, 13 and 13.1 months. Conclusion Brain metastases of differentiated thyroid cancer were relatively uncommon. Prognosis of patients with brain metastasis was unfavorable because of frequent major brain hemorrhage and frequent existence of concomitant extracranial lesions resistant to radioactive iodine therapy. To prevent intracranial hemorrhage, early treatment seemed to be necessary for brain metastases from differentiated thyroid cancer.