DISTRIBUTION OF STEM CELLS IN DIFFERENT THYROID LESIONS IN PATIENTS OF REPRODUCTIVE, MENOPAUSAL AND POST-MENOPAUSAL AGE.

Different studies indicate that cancer stem cells (CSCs) play an important role in the progression and therapy resistance in different cancer types. The aim of our study was to analyse the distribution of CSCs in different thyroid lesions, in reproductive, menopausal and post-menopausal women. Study included altogether 200 formalin-fixed and paraffin-embedded tissue material, with the diagnosis of NIFTP, Hashimoto's thyroiditis, papillary thyroid carcinoma (PTC) and PTC and Hashimoto's thyroiditis co-occurred cases. Normal thyroid gland was used as a control tissue. Stem cell marker - CD44, as well as other markers including Ki67, BCL2, CK19, CD56, ER were investigated with standard immunohistochemical procedure. The results of our study indicated that CD44 stem cell marker, as well as proliferation marker Ki67 is significantly upregulated in PTC cases in all age groups. However, the expression of CD44 and Ki67 is significantly higher in reproductive age patients, compared to patients in menopause and post-menopause. In addition, the expression of CD44 and Ki67 is significantly higher in PTC and Hashimoto's thyroiditis co-occurred cases, compared to cases with PTC only.