Cancer/testis antigen, Kita-Kyushu lung cancer antigen-1 and ABCD stratification for diagnosing gastric cancers

Table 1 Characteristics of 77 patients with gastric cancer

Characteristics	Number of patients, n (%)
Mean age, yr (range)	71.1 (30-86)
Gender
Male	49 (63.6)
Female	28 (36.4)
Depth of invasion
T1	28 (36.4)
T2	25 (32.5)
T3	21 (27.3)
T4	3 (3.9)
Lymph node metastasis
N0	34 (44.2)
N1	14 (18.2)
N2	13 (16.9)
N3	16 (20.8)
Histological type
Well-differentiated adenocarcinoma	42 (54.5)
Poorly-differentiated adenocarcinoma	29 (46.9)
Signet-ring cell carcinoma	1 (1.3)
Carcinoma with lymphoid stroma	3 (3.9)
Mucinous adenocarcinoma	1 (1.3)
Endocrine carcinoma	1 (1.3)
Stage of disease
I	29 (37.7)
II	23 (29.9)
III	12 (15.6)
IV	13 (16.9)
H. pylori infection (IgG titer)
Negative (< 20 U/mL)	17 (22.1)
Positive (≥ 20 U/mL)	60 (77.9)
PGI
≤ 70 ng/mL	76 (98.7)
> 70 ng/mL	1 (1.3)
PG I/PG II
≤ 3	64 (83.1)
> 3	13 (16.9)
PG method
Positive (PG I ≤ 70 and PG I/II ≤ 3)	63 (81.8)
Negative (except the cases described above)	14 (18.2)
ABCD stratification (H. pylori infection/PG method)
A (negative/negative)	3 (3.9)
B (positive/negative)	11 (14.3)
C (positive/positive)	49 (63.6)
D (negative/positive)	14 (18.2)
KK-LC-1
Positive	63 (81.8)
Negative	14 (18.2)

Positive of H. pylori infection; IgG titer ≥ 20 U/mL, Positive of PG method; PG I ≤ 70 ng/mL and PG I/PG II ≤ 3. KK-LC-1: Kita–Kyushu lung cancer antigen-1; H. pylori: Helicobacter pylori.

Table 2 Each serum levels between the patients with and without Kita–Kyushu lung cancer antigen-1 expression (mean ± SE)

	Total (n = 77)	KK-LC-1 positive (n = 63)	KK-LC-1 negative (n = 14)	P value (Welsh’ test)
Anti-H. pylori IgG titer (U/mL)	57.07 ± 10.47	61.76 ± 4.46	35.94 ± 9.47	0.0289
PG I (ng/mL)	16.98 ± 5.03	16.88 ± 2.14	17.39 ± 4.55	0.9226
PG II (ng/mL)	21.01 ± 8.54	23.60 ± 3.64	9.34 ± 7.72	0.0041
PG I/II ratio1 (n = 73)	1.61 ± 0.50	1.38 ± 0.19	2.86 ± 0.46	0.087

¹Four subjects, which levels of PGI were null, were eliminated from PG I/II ratio. KK-LC-1: Kita–Kyushu lung cancer antigen-1; H. pylori: Helicobacter pylori.

Table 3 Expression of Kita–Kyushu lung cancer antigen-1 and parameters

		Total (n = 77)	KK-LC-1 positive (n = 63)	KK-LC-1 negative (n = 14)	KK-LC-1 expression rate (%)	P value
Anti-H. pylori IgG titer	< 20 U/mL: negative	17	9	8	52.9	0.0087
	≥ 20 U/mL: positive	60	54	6	90
PG I	≤ 70 ng/mL	76	62	14	81.5	0.9226 (NS)
	> 70 ng/mL	1	1	0	100
PG I/PG II ratio	≤ 3	64	55	9	85.9	0.0526 (NS)
	> 3	13	8	5	61.5
PG method	PG I ≤ 70 and PG I/II ≤ 3	63	54	9	85.7	0.1173 (NS)
	Other	14	9	5	64.3
ABCD stratification (H. pylori infection/PG method)	A (negative/negative)	3	1	2	33	0.0005 (C vs others, Fisher’s exact test)
	B (positive/negative)	11	8	3	72.7
	C (positive/positive)	49	46	3	93.9
	D (negative/positive)	14	8	6	57.1

KK-LC-1: Kita–Kyushu lung cancer antigen-1; H. pylori: Helicobacter pylori; NS: Not significant.

Table 4 Expression of Kita–Kyushu lung cancer antigen-1 in ABCD stratification by each stage, positive/total (%)

Stage	ABCD stratification
	A	B	C	D	Total
I	-	3/6 (50)	18/18 (100)	2/5 (40)	22/29 (76)
II	1/3 (33)	3/3 (100)	12/12 (100)	4/5 (80)	20/23 (87)
III	-	1/1 (100)	8/10 (80)	0/1 (0)	9/12 (75)
IV	-	1/1 (100)	8/9 (89)	3/3 (100)	12/13 (85)
Total	1/3 (33)	8/11 (73)	46/49 (94)	8/14 (57)	63/77 (82)