Table I.

Association between PD-L1 expression and clinicopathological factors in patients with esophageal squamous cell carcinoma.

	PD-L1
Variable	+	−	P-value
Age, years			0.312
<65	48	159
≥65	12	27
Sex, n			0.942
Female	6	18
Male	54	168
CCI			0.600
Low	8	19
Moderate	51	160
High	1	7
Vessel invasion			0.137
Yes	13	59
No	47	127
Differentiation			0.542
Well	17	67
Moderate	36	101
Poor	7	18
Tumor location			0.209
Upper	21	77
Middle	39	103
Lower	0	6
T stage			0.109
1–2	10	136
3–4	50	50
N stage			0.213
0–1	33	119
2–3	27	67
TMN stagea			0.022
II	27	132
III	33	54
Smoking history			0.837
Yes	47	148
No	13	38
Alcohol consumption			0.892
Yes	46	141
No	14	45

^aAccording to the 7th American Joint Committee on Cancer guidelines. CCI, Charlson comorbidity index; TNM, tumor-node metastasis; T stage, tumor stage; N stage, node stage; PD-L1, programmed death-ligand 1.