Mcm-2 and Ki-67 have limited potential in preoperative diagnosis of thyroid malignancy.
OBJECTIVE
Minichromosome maintenance protein 2 (Mcm-2) is essential for DNA replication and serves as a useful biomarker of cell-cycle state in human tissue samples. Ki-67 is an established proliferation marker. Because Mcm-2 expression has not previously been assessed in thyroid tissue, the aim of this study was to assess the expression of both proteins in a range of thyroid lesions to determine their potential value as preoperative markers of thyroid malignancy.


METHODS
Mcm-2 and Ki-67 protein expression were assessed by immunohistochemistry in formalin-fixed, paraffin-embedded thyroid tissues from 128 patients with histologic diagnoses of papillary carcinoma (n = 38), follicular carcinoma (n = 22), follicular adenoma (n = 33), and dominant nodules of multinodular goitre (n = 35).


RESULTS
Mcm-2 and Ki-67-labeling indices (LIs) were both higher in follicular and papillary carcinomas than in follicular adenomas or dominant nodules. The Ki-67 LI discriminated better between follicular carcinomas and follicular adenomas (P < .0001) than Mcm-2 (P = .0273). However, the Mcm-2 and Ki-67 LIs overlapped widely between the four histologic groups, and the expression of these proteins was also noted to be heterogenous within these lesions.


CONCLUSIONS
Neither Mcm-2 or Ki-67 can currently be reliably applied as preoperative markers to distinguish benign from malignant thyroid lesions.
Mehrotra
Pallavi
P
School of Surgical and Reproductive Sciences, Department of Cellular Pathology, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom.
Gonzalez
Michael A
MA
Johnson
Sarah J
SJ
Coleman
Nick
N
Wilson
Janet A
JA
Davies
Barry R
BR
Lennard
Tom W J
TW
D000236:Adenoma / Q000175:diagnosis; D014408:Biomarkers, Tumor / Q000032:analysis*; D002291:Carcinoma, Papillary / Q000175:diagnosis; D018797:Cell Cycle Proteins / Q000032:analysis*; D006044:Goiter, Nodular / Q000175:diagnosis; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis*; D064111:Minichromosome Maintenance Complex Component 2; D009687:Nuclear Proteins / Q000032:analysis*; D013961:Thyroid Gland / Q000737:chemistry; D013964:Thyroid Neoplasms / Q000175:diagnosis*
D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D019394:Ki-67 Antigen; D009687:Nuclear Proteins; C084859:MCM2 protein, human; D064111:Minichromosome Maintenance Complex Component 2