Table 6.

Univariate analysis of overall survival in cyclooxygenase-2 (COX-2) negative and positive groups among patients with esophageal squamous cell carcinoma in group A.

Variable	Group	Median survival time (months)			P-value
		Negative COX-2	Low COX-2	High COX-2
Sex	Male	65	28	51	0.38
	Female	--a	--a	35
Age, years	≤60	--a	28	35	0.92
	>60	50	30	51
History of smoking	Yes	57	30	--a	0.81
	No	74	29	36
History of alcohol use	Yes	43	15	51	0.20
	No	65	30	36
History of hypertension	Yes	65	30	37	0.63
	No	57	15	36
History of CHD	Yes	--a	14	37	0.75
	No	57	30	36
History of diabetes	Yes	65	35	22	0.83
	No	57	28	37
Tumor location	Upper 1/3 thoracic segment	54	14	37	0.82
	Middle 1/3	65	28	51
	Lower 1/3	74	30	35
Tumor size, cm	<5	--a	30	36	0.03
	≥5	43	26	51
Degree of differentiation	Undetermined and well differentiated	65	30	37	0.13
	Moderate and poorly differentiated	35	14	36
T stage	T1 + T2	65	68	--a	0.00
	T3 + T4	54	20	35
N stage	N0	74	30	37	0.02
	N1	65	26	--a
	N2 + N3	30	15	36
TNM stage	0 + I	--a	30	32	0.02
	II	43	68	51
	III	--a	15	22
Lymph node metastasis	Yes	65	17	36	0.07
	No	74	30	37
LNR	0	--c	--c	--c	0.05
	>0 to ≤0.1	--c	--c	--c
	>0.1	--c	--c	--c
Margin-positive	Yes	54	14	51	0.95
	No	65	29	36
Vascular tumor invasion	Yes	29	15	14	0.02
	No	65	30	36
Neural tumor invasion	Yes	--c	--c	--c	0.82
	No	--c	--c	--c
Neoadjuvant radiochemotherapy	Yes	--	22	3	--b
	No	65	30	37
Postoperative complication	Yes	74	30	51	0.79
	No	57	29	36
Postoperative neoadjuvant therapy	No adjuvant therapy	--c	--c	--c	0.55
	Chemotherapy alone	--c	--c	--c
	Radiochemotherapy	--c	--c	--c

^aIf the estimate had been censored, it would be limited to the longest survival time; ^bno pooled comparison because at least one layer had no valid cases for every factor level; ^cno statistical analysis because all cases censored

CHD, coronary heart disease; LNR, lymph node ratio.