Short- and mid-term efficacy of percutaneous ethanol injection in cystic and predominantly cystic thyroid nodules: systematic review and meta-analysis

Abstract Objective To evaluate the short- and mid-term volume reduction rate(VRR) after percutaneous ethanol injection(PEI), at 1,3 and 6 months, in patients with cystic or predominantly cystic thyroid nodules(CNs/pCNs, respectively), conducting a systematic review and meta-analysis of published data on VRR outcomes across these intervals. Design and methods A systematic search of articles published up to October 30,2025 identified studies reporting PEI treatment for CNs/pCNs.Characteristics of the study design, CNs/pCNs cohorts, and outcomes of interest(VRR at 1,3 and 6 months of follow up)were extracted.Statistical analysis included a random-effects meta-analysis, assessment of heterogeneity with use of the I 2 statistic, and meta-regression and subgroup analyses to explore potential sources of heterogeneity. Results Six studies comprising 431 CNs/pCNs were included.The pooled VRRs at 1,3 and 6 months post-PEI were 85.18%(95% CI: 80.72–89.64),91.50%(95% CI: 88.88–94.12) and 93.11%(95% CI: 90.91–95.31),respectively. Stratifying by nodule cystic composition, the VRR at consecutive follow-up time points was significantly different between the 1- and 3-month intervals in both subgroups [CN: VRRs at 1, 3 and 6 months were 91.16% (88.38–93.93), 95.69% (94.16–97.22) and 96.02% (94.16–97.87), respectively; pCN: VRRs at 1,3 and 6 months were respectively 80.19% (77.04–83.33), 87.08% (84.95–89.2) and 90.01%(88.83–91.19)].A secondary meta-regression analysis with baseline mean volume as covariate demonstrated a significant inverse association with VRR at 1 and 3 months in pCN( p = 0.02). Conclusion By providing pooled VRRs for the short- and mid-term follow-up, this meta-analysis should be regarded as an initial step, paving the way for larger, high-quality studies aimed at standardizing the PEI procedure and supporting its incorporation into future dedicated guidelines.