CD8+ TIL recruitment may revert the association of MAGE A3 with aggressive features in thyroid tumors.

Background: We aimed to investigate a possible role of MAGE A3 and its associations with infiltrated immune cells in thyroid malignancy, analyzing their utility as a diagnostic and prognostic marker.

Materials And Methods: We studied 195 malignant tissues: 154 PTCs and 41 FTCs; 102 benign tissues: 51 follicular adenomas and 51 goiter and 17 normal thyroid tissues. MAGE A3 and immune cell markers (CD4 and CD8) were evaluated using immunohistochemistry and compared with clinical pathological features.

Results: The semiquantitative analysis and ACIS III analysis showed similar results. MAGE A3 was expressed in more malignant than in benign lesions (P < 0.0001), also helping to discriminate follicular-patterned lesions. It was also higher in tumors in which there was extrathyroidal invasion (P = 0.0206) and in patients with stage II disease (P = 0.0107). MAGE A3+ tumors were more likely to present CD8+ TIL (P = 0.0346), and these tumors were associated with less aggressive features, that is, extrathyroidal invasion and small size. There was a trend of MAGE A3+ CD8+ tumors to evolve free of disease.

Conclusion: We demonstrated that MAGE A3 and CD8+ TIL infiltration may play an important role in malignant thyroid nodules, presenting an interesting perspective for new researches on DTC immunotherapy.