The significance of Galectin-3 expression in the immunocytochemical evaluation of thyroid fine needle aspiration cytology

Systematic Review and Meta-Analysis to Identify the Immunocytochemical Markers Effective in Delineating Benign from Malignant Thyroid Lesions in FNAC Samples

Conventional cytology-based diagnosis for thyroid cancer is limited with more than 30-45% of nodules categorized as indeterminate, necessitating surgery for confirming or refuting the diagnosis. This systematic review and meta-analysis were aimed at identifying immunocytochemical markers effective in delineating benign from malignant thyroid lesions in fine needle aspiration cytology (FNAC) samples, thereby improving the accuracy of cytology diagnosis. A systematic review of relevant articles (2000-2021) from online databases was carried out and the search protocol registered in PROSPERO database (CRD42021229121). The quality of studies was assessed using QUADAS-2. Review Manager 5.4.1 from Cochrane collaboration and MetaDisc Version 1.4 was used to conduct the meta-analysis. Bias in the studies were visually analyzed using funnel plots, and statistical significance was evaluated by Egger's test. Systematic review identified 64 original articles, while meta-analysis in eligible articles (n = 41) identified a panel of 5 markers, Galectin-3, HBME-1, CK-19, CD-56, and TPO. Assessment of the diagnostic performance revealed that Gal-3 (sensitivity: 0.81; CI: 0.79-0.83; specificity: 0.84; CI: 0.82-0.85) and HBME-1 (sensitivity: 0.83; Cl: 0.81-0.86; specificity: 0.85; CI: 0.83-0.86) showed high accuracy in delineating benign from malignant thyroid nodules. Efficacy analysis in indeterminate nodules showed Gal-3 and HBME-1 have high specificity of 0.86 (CI 0.84-0.89) and 0.82 (CI 0.78-0.86), respectively, and low sensitivity of 0.76 (CI 0.72-0.80) and 0.75 (CI 0.70-0.80), respectively. Diagnostic odds ratio (DOR) of Galectin-3 and HBME-1 were 39.18 (CI 23.38-65.65) and 24.44 (CI 11.16-53.54), respectively. Significant publication bias was observed for the markers Galectin-3 and CK-19 (p < 0.05). The panel of 5 markers identified from this meta-analysis are high-confidence candidates that need to be validated in thyroid cytology to establish their efficacy and enable clinical applicability.

Contribution of immunocytochemical stainings for galectin-3, CD44, and HBME1 to fine-needle aspiration cytology diagnosis of papillary thyroid carcinoma

In cytology practice some papillary thyroid carcinoma (PTC) cases have indeterminate diagnoses and overlapping cytological features with benign lesions. This study was undertaken to find out if immunocytochemistry using Galectin-3, CD-44 and HBME-1 could be of help in such situations. Forty-six cases consisting of 22 malignancy (PTC) cases, 7 suspicious of (S/O) PTC, 1 follicular neoplasm, 5 follicular lesion of undetermined significance (FLUS), and 11 benign (colloid goiter) cases diagnosed by FNA were included in this study. Staining reactions were graded in a sliding scale of -, 1+, 2+, 3+, and 4+. In an assessment of 100 cells, each cell with weak, and moderate to strong positive reaction were assigned a score of 1 and 4, respectively. Staining reaction of ≥+2 and scores >100 were considered positive. Frequency of cases with ≥+2 reaction, and scores >100 for each of Galectin-3, CD-44, and HBME-1 were significantly higher in PTC or combined PTC and S/O PTC cases as compared with FLUS and benign cases taken together (P = 0.01744 to 0.00000). When the cases were compared according to histological malignant and benign diagnoses, the difference was also significant in respect of ≥+2 reaction, and scores >100 for Galectin-3 and CD44 (P = 0.04923 to 0.00947); however, there was no significant difference, when these parameters for HBME1 were compared. Galectin 3, CD 44, and to some extent HBME 1 are useful immunocytochemical parameters with potential to support FNAC diagnosis of PTC, especially in situations with difficult differential diagnoses.

Diagnostic utility of galectin-3 in thyroid cancer

Galectin-3 (Gal-3), which has received significant recent attention for its utility as a diagnostic marker for thyroid cancer, represents the most well-studied molecular candidate for thyroid cancer diagnosis. Gal-3 is a protein that binds to beta-galactosidase residues on cell surface glycoproteins and has also been identified in the cytoplasmic and nuclear compartment. This marker has been implicated in regulation of normal cellular proliferation and apoptosis, as well as malignant transformation and the metastasis of cancer cells. We here present a mechanistic review of Gal-3 and its role in cancer development and progression. Gal-3 expression studies in thyroid tissue and cytologic tumor specimens and their methodological considerations are also discussed in this article. Despite great variance in their methodology, the majority of immunohistochemical studies found that Gal-3 was differentially expressed in thyroid carcinoma compared with benign and normal thyroid specimens, suggesting that Gal-3 is a good diagnostic marker for thyroid cancer. Recent studies have also demonstrated improved methodological reliability. On the other hand, Gal-3 genomic expression studies have shown inconsistent results for diagnostic utility and are not recommended. Overall, the development of Gal-3 as a diagnostic marker for thyroid cancer represents a promising avenue for future study, and its clinical application could significantly reduce the number of diagnostic thyroid operations performed for cases of indeterminant fine needle aspiration biopsy cytology, and thus positively impact the current management of thyroid nodular disease.