Garibotto, N.3, Aghajani, M.J.1,2, Yang, T.1,2,4,, McCafferty, C.E.2, Graham, S.1,2,3, Wu, X.4, Niles, N.1,2,3.
1 Thyroid Cancer Group, Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
2 School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
3 Department of Head & Neck Surgery, Liverpool Hospital, Liverpool, NSW, Australia
4 Department of Anatomical Pathology, Liverpool Hospital, Liverpool, NSW, Australia
Background: Thyroid gland carcinoma is the most common malignant endocrine tumour, irrespective of ethnicity or geographic location (1). Few markers are currently available for guiding treatment and stratifying thyroid cancer patients (2). There is increasing evidence supporting the prognostic significance of tumour-infiltrating lymphocytes (TILs) (3); however, their significance with respect to thyroid cancer remains uncertain. Our aim was to investigate the association between CD3+ and CD8+ TIL density in papillary thyroid cancer (PTC) and disease severity.
Methods: This retrospective study examined 75 PTC tissue samples obtained from patients who underwent surgery in the South West Sydney Local Health District. Stained cells were manually counted and analysed for clinical and histopathological correlations, and disease-free survival (DFS).
Results: Cases with low CD8+ and CD3+ expression presented with a significantly higher incidence of extrathyroidal extension (p=0.015) and lymph node metastasis (p=0.042). Univariate and multivariate analysis revealed that high CD8+ T cell density was significantly associated with favourable DFS (p=0.026). Sub-analysis demonstrated that the shortest DFS was observed in the CD8low/CD3low group (p=0.015).
Discussion: The presence of elevated CD3+ and CD8+ TILs has been associated with a favourable outcome across multiple tumour types (4). In agreement with these studies, our results suggest that the frequency of CD8+ and CD3+ TILs may serve as a significant prognostic biomarker in PTC.
Conclusion: Our findings indicate that the density of CD3+ and CD8+ TILs may function as a valuable prognostic biomarker in PTC, and identify patients likely to benefit from long-term surveillance and adjuvant treatment.
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