Table 2. Clinicopathological characteristics of patients in cohort 2 according to their PIK3CA mutation status.

Characteristics	PIK3CA wild-type	PIK3CA mutant	p-value
	(n = 105) (%)	(n = 15) (%)
Sex
Male	70 (66.7)	7 (46.7)	0.131
Female	35 (33.3)	8 (53.3)
Age
< 70 years	83 (79.0)	10 (66.7)	0.324
≥ 70 years	22 (21.0)	5 (33.3)
Primary tumor location*
Lower third	47 (45.2)	7 (46.7)	0.395
Middle third	28 (26.9)	6 (40.0)
Upper third	29 (27.9)	2 (13.3)
Pathology
Well or moderately differentiated adenocarcinoma	28 (26.7)	4 (26.7)	0.801
Poorly differentiated adenocarcinoma	58 (55.2)	9 (60.0)
Signet ring cell carcinoma	11 (10.5)	1 (6.7)
Mucinous carcinoma	8 (7.6)	1 (6.7)
Lauren classification
Intestinal type	29 (27.6)	7 (46.7)	0.107
Diffuse type	72 (68.6)	8 (53.3)
Mixed type	4 (3.8)	0 (0)
T stage
pT1/T2/T3	17 (16.2)	1 (6.7)	0.464
pT4	88 (83.8)	14 (93.3)
N stage
pN0/N1/N2	21 (20.0)	2 (13.3)	0.733
pN3	84 (80.0)	13 (86.7)
Lymphatic invasion
Absent	11 (10.5)	2 (13.3)	0.666
Present	94 (89.5)	13 (86.7)
Vascular invasion
Absent	55 (52.4)	3 (20.0)	0.019
Present	50 (47.6)	12 (80.0)
Perineural invasion
Absent	16 (15.2)	2 (13.3)	1.000
Present	89 (84.8)	13 (86.7)
Stroma reaction
Absent	59 (56.2)	8 (53.3)	0.868
Desmoplasia	39 (37.2)	6 (40.0)
Lymphoid or neutrophil	7 (6.7)	1 (6.7)
EBER in situ hybridization
Negative	100 (95.2)	14 (93.3)	0.559
Positive	5 (4.8)	1 (6.7)
MSI
MSS	101 (96.2)	12 (80.0)	0.041
MSI-H	4 (3.8)	3 (20.0)
Gastrectomy
Subtotal gastrectomy	56 (53.3)	9 (60.0)	0.628
Total gastrectomy	49 (46.7)	6 (40.0)
Akt expression (cytoplasmic intensity)
Negative	11 (11.5)	1 (6.7)	0.018
1+	74 (77.1)	10 (66.7)
2+	9 (9.4)	2 (13.3)
3+	2 (2.1)	2 (13.3)

Abbreviations: AJCC = American Joint Committee on Cancer; EBER = Epstein-Barr virus-encoded small RNA.

*Patients whose disease involved the entire stomach (n = 1) were excluded.