Tumor Immunity is Related to 18F-FDG Uptake in Thymic Epithelial Tumor
Background
2-Deoxy-2-[fluorine-18]-fluoro-d-glucose (18F-FDG) positron emission tomography (18F-FDG-PET) is a convenient modality to assess metabolic activity within tumor cells. However, there is no consensus regarding the relationship between 18F-FDG uptake and the immune environment in thymic epithelial tumors (TETs). We conducted a clinicopathological study to elucidate the relationship between 18F-FDG uptake and programmed death ligands 1 and 2 (PD-L1/PD-L2) expression in patients with TETs.
Methods
A total of 108 patients with histologically confirmed TETs classified as thymomas or thymic carcinomas who underwent surgical resection or biopsy or needle biopsy and 18F-FDG PET before any treatment between August 2007 and March 2020 were enrolled in this study. Tumor specimens underwent immunohistochemical staining for PD-L1, PD-L2, GLUT1, HIF-1α, VEGFR2, VEGF-C and β2 adrenergic receptor.
Results
High uptakes of SUVmax, SUVmean, MTV and TLG were identified in 28 (25.9%), 61 (56.5%), 55 (50.9%) and 55 (50.9%) of 108 patients, respectively. High uptake of SUVmax significantly correlated with PS of 1-2, thymic carcinoma and advanced stage, and SUVmax on 18F-FDG uptake displayed a close association with PD-L1 and PD-L2 expression, but not MTV and TLG. Multivariate analysis revealed that SUVmax was identified as an independent predictor for positive PD-L1 /PD-L2 expression. GLUT1 was clarified as a significant marker for the expression of PD-L1/PD-L2 from the biological viewpoint.
Conclusion
18F-FDG accumulation was closely associated with the expression of PD-L1/PD-L2, which, in turn, was correlated with glucose metabolism and hypoxia. PD-L1/PD-L2 could affect glucose metabolism and hypoxia in thymic tumor cells.
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Posted 16 Dec, 2020
Received 10 Jan, 2021
On 10 Jan, 2021
Received 09 Jan, 2021
On 30 Dec, 2020
On 30 Dec, 2020
Received 26 Dec, 2020
Received 25 Dec, 2020
On 15 Dec, 2020
On 13 Dec, 2020
Invitations sent on 11 Dec, 2020
On 10 Dec, 2020
On 10 Dec, 2020
On 10 Dec, 2020
On 08 Dec, 2020
Tumor Immunity is Related to 18F-FDG Uptake in Thymic Epithelial Tumor
Posted 16 Dec, 2020
Received 10 Jan, 2021
On 10 Jan, 2021
Received 09 Jan, 2021
On 30 Dec, 2020
On 30 Dec, 2020
Received 26 Dec, 2020
Received 25 Dec, 2020
On 15 Dec, 2020
On 13 Dec, 2020
Invitations sent on 11 Dec, 2020
On 10 Dec, 2020
On 10 Dec, 2020
On 10 Dec, 2020
On 08 Dec, 2020
Background
2-Deoxy-2-[fluorine-18]-fluoro-d-glucose (18F-FDG) positron emission tomography (18F-FDG-PET) is a convenient modality to assess metabolic activity within tumor cells. However, there is no consensus regarding the relationship between 18F-FDG uptake and the immune environment in thymic epithelial tumors (TETs). We conducted a clinicopathological study to elucidate the relationship between 18F-FDG uptake and programmed death ligands 1 and 2 (PD-L1/PD-L2) expression in patients with TETs.
Methods
A total of 108 patients with histologically confirmed TETs classified as thymomas or thymic carcinomas who underwent surgical resection or biopsy or needle biopsy and 18F-FDG PET before any treatment between August 2007 and March 2020 were enrolled in this study. Tumor specimens underwent immunohistochemical staining for PD-L1, PD-L2, GLUT1, HIF-1α, VEGFR2, VEGF-C and β2 adrenergic receptor.
Results
High uptakes of SUVmax, SUVmean, MTV and TLG were identified in 28 (25.9%), 61 (56.5%), 55 (50.9%) and 55 (50.9%) of 108 patients, respectively. High uptake of SUVmax significantly correlated with PS of 1-2, thymic carcinoma and advanced stage, and SUVmax on 18F-FDG uptake displayed a close association with PD-L1 and PD-L2 expression, but not MTV and TLG. Multivariate analysis revealed that SUVmax was identified as an independent predictor for positive PD-L1 /PD-L2 expression. GLUT1 was clarified as a significant marker for the expression of PD-L1/PD-L2 from the biological viewpoint.
Conclusion
18F-FDG accumulation was closely associated with the expression of PD-L1/PD-L2, which, in turn, was correlated with glucose metabolism and hypoxia. PD-L1/PD-L2 could affect glucose metabolism and hypoxia in thymic tumor cells.
Figure 1
Figure 2
Figure 3