Maryam Hejazi, Ramin Heshmat, Gita Shafiee, Bagher Larijani, Amir Ali Mokhtarzadeh, Vida Ebrahimi, Seyed Mohammad Tavangar
Background/Objectives: Thyroid cancer (TC) is the most common type of endocrine neoplasm and is increasing in incidence, particularly papillary thyroid carcinoma (PTC). Early-stage disease has a favorable prognosis; however, advanced forms, such as anaplastic thyroid carcinoma, complicate treatment. Long non-coding RNAs (lncRNAs), longer than 200 nucleotides and non-coding, together with microRNAs, have emerged as major regulators of TC pathogenesis. This review summarizes data on how dysregulated lncRNAs influence the hallmarks of cancer in thyroid malignancies. Methods: We reviewed the literature on the role of lncRNAs and microRNAs in TC, focusing on their functions as competing endogenous RNAs (ceRNAs), regulators of PI3K/AKT and Wnt/β-catenin pathways, and controllers of epigenetic alterations. Results: Dysregulated lncRNAs contribute to hallmarks including sustained growth, evading suppressors, resisting death, replicative immortality, angiogenesis, invasion, metabolic reprogramming, immune evasion, genomic instability, and tumor-promoting inflammation. ceRNA mechanisms amplify immune evasion by regulating checkpoint proteins and cytokines, altering immune cell activity. Altered lncRNA profiles correlate with aggressiveness, metastasis, and prognosis. Notable lncRNAs, such as H19, MALAT1, and DOCK9-AS2, dysregulate oncogenic pathways and represent potential biomarkers. Conclusions: Advances in therapeutics suggest inhibiting oncogenic lncRNAs or restoring tumor-suppressive lncRNAs via RNA interference, antisense oligonucleotides, or CRISPR/Cas9 editing. New technologies, including single-cell RNA sequencing and spatial transcriptomics, will improve understanding of heterogeneous lncRNA–microRNA networks in TC and support precision medicine. LncRNAs signify both molecular drivers and clinical targets for thyroid cancer.