Significance of monitoring imatinib plasma concentration in second-line treatment decisions for c-kit 11 gene-mutated gastrointestinal stromal tumors

Table 2 Baseline characteristics of patient subgroups, n (%)

Characteristics	LP (n = 28)			HP (n = 37)
	Group A (n = 14)	Group B (n = 14)	P value	Group A (n = 18)	Group B (n = 29)	P value
Age	51 ± 12	53 ± 12	0.611	51 ± 19	52 ± 13	0.785
Sex			> 0.9991			> 0.999
Male	11 (79)	10 (71)		14 (78)	23 (79)
Female	3 (21)	4 (29)		4 (22)	6 (21)
Primary tumor site			0.3561			0.5981
Stomach	6 (43)	2 (14)		6 (33)	8 (28)
Small intestine	5 (36)	7 (50)		9 (50)	12 (41)
Other	3 (21)	5 (36)		3 (17)	9 (31)
Mitotic count (/50 HPF)			0.1841			0.408
≤ 5	7 (50)	12 (86)		6 (33)	15 (52)
5 to ≤ 10	4 (29)	1 (7)		6 (33)	6 (21)
> 10	3 (21)	1 (7)		6 (33)	8 (28)
Ki 67			> 0.999			0.096
≤ 10	8 (57)	8 (57)		8 (44)	20 (69)
> 10	6 (43)	6 (43)		10 (56)	9 (31)
Risk classification			> 0.9991			> 0.9991
Medium	1 (7)	0 (0)		0 (0)	1 (3)
High	13 (93)	14 (100)		18 (100)	28 (97)
Mutation type			0.2091			> 0.9991
Point mutation	2 (14)	6 (43)		4 (22)	7 (24)
Delete mutation	11 (79)	8 (57)		14 (78)	21 (72)
Other	1 (7)	0 (0)		0 (0)	1 (3)
Sum of largest diameter (cm)			0.7971			0.520
≤ 5	6 (43)	5 (36)		4 (22)	7 (24)
5-10	4 (29)	3 (21)		6 (33)	5 (17)
> 10	4 (29)	6 (43)		8 (44)	17 (59)
Lesions > 3			0.450			0.869
Yes	6 (43)	8 (57)		12 (67)	20 (69)
No	8 (57)	6 (43)		6 (33)	9 (31)
R0 resection			> 0.999			0.236
Yes	5 (36)	5 (36)		8 (44)	8 (28)
No	9 (64)	9 (64)		10 (56)	21 (72)

¹Using the Fisher’s exact test.

HP: High plasma concentration group; HPF: High-power field; LP: Low plasma concentration group.