IGF2 differentially methylated region hypomethylation in relation to pathological and molecular features of serrated lesions

Table 2 Clinical and molecular features of serrated lesions and non-serrated adenomas (tubular or tubulovillous adenoma) according to histological type n (%)

Clinical or molecular feature	Total n	Histological type						P value
		Serrated lesion				Non-serrated adenoma
		HP	SSA without cytological dysplasia	SSA with cytological dysplasia	TSA without high-grade dysplasia (HGD)	Tubular adenoma without HGD	Tubulovillous adenoma without HGD
All cases	416	115	120	10	91	77	3
Sex
Male	263 (63)	78 (68)	72 (60)	5 (50)	55 (60)	50 (65)	3 (100)	0.36
Female	153 (37)	37 (32)	48 (40)	5 (50)	36 (40)	27 (35)	0 (0)
Age (mean ± SD)	60.3 ± 11.8	57.5 ± 12.1	57.2 ± 11.6	74.1 ± 4.7	60.9 ± 12.3	66.6 ± 11.4	66.0 ± 8.9	< 0.0001
Tumor size (mm)	10.5 ± 5.4	9.3 ± 3.7	11.6 ± 5.4	12.3 ± 6.4	9.7 ± 4.7	10.9 ± 7.2	15.7 ± 13.2	0.0069
(mean ± SD)
Tumor location
Rectum	42 (10)	15 (13)	0 (0)	0 (0)	16 (18)	10 (14)	1 (33)	< 0.0001
Distal colon	127 (31)	44 (39)	17 (14)	1 (10)	39 (44)	25 (34)	1 (33)
Proximal colon	239 (59)	54 (48)	103 (86)	9 (90)	34 (38)	38 (52)	1 (33)
BRAF mutation
Wild-type	183 (44)	59 (51)	16 (13)	2 (20)	28 (31)	75 (97)	3 (100)	< 0.0001
Mutant	231 (55)	56 (49)	104 (87)	8 (80)	61 (69)	2 (2.6)	0 (0)
KRAS mutation
Wild-type	357 (87)	92 (81)	117 (98)	10 (100)	74 (83)	62 (81)	2 (67)	< 0.0001
Mutant	55 (13)	21 (19)	3 (2.5)	0 (0)	15 (17)	15 (19)	1 (33)
PIK3CA mutation
Wild-type	406 (99)	113 (99)	117 (100)	10 (100)	89 (100)	74 (99)	3 (100)	0.67
Mutant	2 (0.5)	1 (0.9)	0 (0)	0 (0)	0 (0)	1 (1.3)	0 (0)
MSI status
MSS/MSI-low	408 (98)	113 (98)	119 (99)	6 (60)	90 (99)	77 (100)	3 (100)	0.0004
MSI-high	8 (1.9)	2 (1.7)	1 (0.8)	4 (40)	1 (1.1)	0 (0)	0 (0)
IGF2 DMR0	64.5 ± 17.2	61.9 ± 20.5	73.1 ± 12.3	69.0 ± 10.8	61.6 ± 19.6	58.9 ± 16.1	61.0 ± 7.1	< 0.0001
methylation level (mean ± SD)
LINE-1	58.7 ± 5.0	58.6 ± 3.4	58.1 ± 5.4	58.3 ± 8.4	58.8 ± 4.7	59.4 ± 6.0	60.9 ± 1.4	0.59
methylation level (mean ± SD)

Percentage indicates the proportion of patients of each histological type who met the criteria for a specific clinical or molecular feature. P values were calculated by analysis of variance for age, tumor size, methylation levels of IGF2 DMR0 and LINE-1 and by χ² or Fisher’s exact test for all other variables. The P value for significance was adjusted by Bonferroni correction to 0.0050 (= 0.05/10). HGD: High-grade dysplasia; HP: Hyperplastic polyp; MSI: Microsatellite instability; MSS: Microsatellite stable; SSA: Sessile serrated adenoma; TSA: Traditional serrated adenoma; IGF2: Insulin-like growth factor 2.