Table 2.

The correlation between the PD-1 expression and other clinicopathological parameters

	PD-1 expression		P-value
	+ (84.9%)	- (15.1%)
Age
< 45 years	56	10	0.981
≥ 45 years	51	9
Gender
Female	81	15	0.989
Male	26	4
Tumor size
≤ 2 cm	71	12	0.136
> 2 and ≤4 cm	34	5
> 4 cm	2	2
Extrathyroid invasion
-	27	3	0.550
+	80	16
pT
1b	22	3	0.477
2	6	0
3	79	16
pN
0	41	6	0.350
1a	43	6
1b	23	7
Stage grouping
I + II	16	0	0.095
III	69	12
IVA	22	7
Psamomma body
-	49	9	0.899
+	58	10
Stromal calcification
-	61	4	0.004
+	46	15
Bone formation
-	105	18	0.938
+	2	1
Multifocality
Unifocal	77	11	0.218
Multifocal	30	8
TILs
Poor	74	19	0.011
Rich	33	0
Background disease
CLT	27	0	0.030
Non-CLT	80	19

pT pathological tumor category, pN pathological lymph node category, TILs tumor-infiltrating lymphocytes, CLT chronic lymphocytic thyroiditis