PURPOSE: Metastatic parathyroid carcinoma (PC) is rare and hard to treat. Minimally invasive alternatives to surgery are needed. We aimed to evaluate the effectiveness and safety of microwave ablation (MWA) for lung metastases from PC. METHODS: This retrospective study analyzed data from PC patients undergoing percutaneous MWA for lung metastases at a Chinese tertiary hospital. Primary outcomes included changes in corrected serum calcium (ΔCSC) and parathyroid hormone (ΔPTH), with influencing factors being assessed. Adverse events were also recorded. RESULTS: Six patients received 15 MWA procedures for 21 lung metastases. Serum PTH levels decreased by 40.5 ± 21.5%, with a ΔPTH of 321.1 (240.0, 433.0) pg/mL. CSC levels dropped by 0.27 ± 0.25 mmol/L (P = 0.030), normalizing in 66.7% of MWA sessions. Ablated tumor sizes either reduced slightly or stabilized. The time to reach the lowest PTH and CSC levels was 2.0 (1.0, 7.0) days and 3.0 (1.0, 7.0) days, respectively, with effects lasting 31.5 (19.3, 133.0) days for PTH and 14.0 (14.0, 49.0) days for CSC. Fewer metastases (r = -0.539, P = 0.038
r = -0.660, P = 0.007
respectively) and a higher proportion of ablated nodules (r = 0.568, P = 0.027
r = 0.629, P = 0.012
respectively) were associated with greater PTH and CSC reductions. Common complications included mild pneumothorax and mild hemorrhage (20% each), with no adverse events in about half of the sessions. CONCLUSION: MWA offers a safe and effective option for treating lung metastases in PC patients when surgery is not feasible.