Table 4. Relation between expression of PD-L1, PD-1, TS and clinical characteristics.

Characteristic	Patients (n = 56)	PD-L1			PD-1			TS
		Positive (n = 15)	Negative (n = 41)	P valuea	Positive (n = 19)	Negative (n = 37)	P valuea	Positive (n = 26)	Negative (n = 30)	P valuea
Gender				0.064			0.354			0.642
Male	37	7	30		11	26		18	19
Female	19	8	11		8	11		8	11
Age (years)				0.581			0.143			0.906
<58 years	22	5	17		10	12		10	12
≥58 years	34	10	24		9	25		16	18
Smoking status				0.259			0.067			0.861
Former or current smoker	33	7	26		8	25		15	18
Never smoker	23	8	15		11	12		11	12
Performance status				0.223			0.625			0.757
0-1	42	13	29		15	27		19	23
2	14	2	12		4	10		7	7
Stage				0.460			0.565			0.827
Stage IIIB	8	3	5		2	6		4	4
Stage IV	48	12	36		17	31		22	26
Ki-67 positivity				0.025			0.011			0.832
≤15%	25	3	22		4	21		12	13
>15%	31	12	19		15	16		14	17

PD-L1 = programmed death ligand 1; PD-1 = programmed death protein 1; TS = thymidylate synthase.

a: For this analysis, χ² test and Yates’ correction were applied.