Table 1. Frequency of EGFR mutation according to clinical characteristics in overall patients.

	Positive			Negative		P
	N	N	%	N	%
Age						0.272
< 65	310	112	36.1	198	64
65–75	105	37	35.2	68	65
> 75	32	7	21.9	25	78
Sex						< 0.0001
Male	246	63	25.6	183	74
Female	201	93	46.3	108	54
Smoking						0.001
Yes	212	58	27.4	154	73
No	235	98	41.7	137	58
Family history of malignancy						0.452
Yes	35	13	37.1	22	63
No	412	143	34.7	269	65
Histology						< 0.0001
AD	387	149	38.5	238	62
SCC	39	5	12.8	34	87
ADSC	6	1	16.7	5	83
LCC	4	0	0	4	100
NSCLC	11	1	9.1	10	91
Tumor Site						0.137
Left	203	61	30	142	70
Right	242	94	38.8	148	61
Bilateral	2	1	50	1	50
Region distribution						0.209
Central	135	35	25.9	100	74
East	118	51	43.2	67	57
Northeast	31	12	38.7	19	61
Southeast	35	11	31.4	24	69
South	15	6	40	9	60
West	38	13	34.2	25	66
Northwest	41	14	34.1	27	66
Southwest	34	14	41.2	20	59
Ethnic						0.19
Han	406	145	35.7	261	64
Yi	14	5	35.7	9	64
Bai	7	3	42.9	4	57
Dai	5	1	20	4	80
Naxi	3	0	0	3	100
Hui	4	0	0	4	100
Buliang	2	0	2	2	100
Lisu	2	0	2	2	100
Tujia	1	0	1	1	100
Stage						0.278
Ia	20	10	50	10	50
Ib	30	13	43.3	17	57
IIa	10	3	30	7	70
IIb	12	7	58.3	5	42
IIIa	38	11	28.9	27	71
IIIb	34	9	26.5	25	74
IV	303	103	34	200	66
Brain metastasis						0.203
Yes	64	27	42.2	37	58
No	383	129	33.7	254	66
Sample type						0.026
Tisue	175	74	42.3	101	58
Plasma	256	76	29.7	180	70
Cytology	16	6	37.5	10	63
Xuanwei origin						0.157
Yes	63	27	42.8	36	57
No	384	129	33.6	255	66
Total	447	156	34.9	291	65

Note: AD, adenocarcinoma; SCC, squamous-cell carcinoma; ADSC, adenosquamous carcinoma; LCC, large cell carcinoma; NSCLC, non-small-cell lung cancer.