CyberKnife Radiotherapy: A Novel Approach for Refractory Secondary Hyperparathyroidism in Dialysis Patients-A Case Report.

Secondary hyperparathyroidism (SHPT) is a challenging complication of chronic kidney failure. Here, we report a 41-year-old man on dialysis with refractory SHPT and bone pain, who had a history of medullary thyroid carcinoma surgery and was unwilling to undergo parathyroidectomy due to high surgical risks. The patient underwent CyberKnife radiotherapy with a marginal dose of 27 Gy in 3 fractions. Within a week, his intact parathyroid hormone (iPTH) level dropped significantly from 1,467.32 pg/mL to 507.33 pg/mL, with resolution of bone pain. A 99mTc-MIBI SPECT/CT scan at 3 months post-treatment showed parathyroid nodule shrinkage. At 11-month follow-up, iPTH stabilized with no adverse events. However, iPTH levels rebounded to 862.12 pg/mL at 12 months despite increased cinacalcet dosage. This case highlights CyberKnife as a promising noninvasive option for refractory SHPT, offering precision, safety, and efficacy. However, long-term observation and further studies are required to determine the optimal treatment protocol, including dosage, treatment frequency, and potential adverse reactions. Attention should also be paid to the local and systemic effects of radiation therapy. Future research could explore these aspects to improve the long-term efficacy of CyberKnife treatment for parathyroid adenomas.