Table II.

Association between patient characteristics and AQP1 expression in colon cancer.

Characteristics	AQPa overexpression		P-value
	(−)	(+)
Age (years)
<75	60	32	0.663
≥75	17	11
Gender
Male	40	25	0.513
Female	37	18
Tumor location
Right	42	15	0.038
Left	35	28
Depth of invasion
pT1	1	0	0.779
pT2	5	3
pT3	54	27
pT4a	11	11
pT4b	6	2
Bowel obstruction
Yes	8	6	0.774
No	69	37
Lymph node involvement
pN0	38	13	0.042
pN1, N2	39	30
Differentiation
High, moderate	68	42	0.151
Poor/Muc/Sig	9	1
Lymphovascular invasion
Negative-mild	64	27	0.012
Severe	13	16
Vascular invasion
Negative-mild	59	24	0.017
Severe	18	19
CEA
<3.5	42	27	0.476
≥3.5	31	15
CA19-9
<37	55	33	0.517
≥37	16	6
Postoperative chemotherapy
Yes	39	30	0.057
No	38	13
Recurrence
Yes	16	15	0.090
No	61	28

^aAquaporin-1 (AQP1) expression was defined as positive when the sum of the intensity and the extent scores was 3/4 and as negative when the score was 0–2. The AQP1 expression exhibited a significant correlation with lymph node metastasis (P=0.042), severe lymphovascular invasion (P=0.012) and vascular invasion (P=0.017). The AQP1 expression was also higher in left-sided compared to right-sided colon cancer (P=0.038). Only 1/10 of poorly differentiated adenocarcinomas expressed AQP1, although the difference was not statistically significant. Right, ascending and transverse colon; Left, descending and sigmoid colon; Muc, mucinous carcinoma; Sig, signet ring cell carcinoma; CEA, carcinoembryonic antigen; CA, carbohydrate antigen.