Table 1.

Clinical and Molecular Features of Non–MSI-High Colorectal Cancer According to 18q LOH Status

Clinical or Molecular Feature	Total		18q LOH Negative		18q LOH Positive		P
	No.	%	No.	%	No.	%
Total No. of patients	555		193		362
Sex							.36
Male, HPFS	244	44	90	47	154	43
Female, NHS	311	56	103	53	208	57
Age, years							.27
Mean	66.8		67.3		66.5
SD	8.3		8.4		8.2
Body mass index, kg/m2							.018
< 30	424	82	154	88	270	80
≥ 30	90	18	21	12	69	20
Family history of colorectal cancer in first-degree relative(s)							.55
No	428	77	146	76	282	78
Yes	127	23	47	24	80	22
Year of diagnosis							.42
Before 1995	223	40	82	42	141	39
1995 to 2002	332	60	111	58	221	61
Tumor location							.025
Proximal, cecum to transverse	217	40	89	48	128	36
Distal colon, splenic flexure to sigmoid	178	33	50	27	128	36
Rectum	144	27	48	26	96	27
AJCC tumor stage							.26
I	131	24	43	22	88	24
IIA	122	22	42	22	80	22
IIB	13	2.3	7	3.6	6	1.7
IIIA	24	4.3	12	6.2	12	3.3
IIIB	75	14	19	9.8	56	15
IIIC	64	12	23	12	41	11
IV	84	15	29	15	55	15
Unknown	42	7.6	18	9.3	24	6.6
Tumor grade							.0060
Low	506	93	167	89	339	95
High	36	6.6	20	11	16	4.5
MSI status							.80
MSS	495	89	173	90	322	89
MSI low	60	11	20	10	40	11
CIMP, No. of methylated CIMP markers							.095
CIMP 0	272	50	82	44	190	54
CIMP low (1–5)	233	43	90	48	143	41
CIMP high (6–8)	34	6.3	14	7.5	20	5.7
LINE-1 methylation, %							.040
Mean	60.7	61.9	60.1
SD	9.3		9.5		9.2
BRAFmutation							.45
Negative	497	91	170	90	327	92
Positive	48	8.8	19	10	29	8.2
KRASmutation							.015
Negative	330	60	101	53	229	63
Positive	224	40	91	47	133	37
PIK3CA mutation							.11
Negative	438	85	145	82	293	87
Positive	75	15	32	18	43	13
p53 expression							.071
Negative	292	53	110	59	182	51
Positive	254	47	77	41	177	49
β-catenin activation*							.30
Inactive (score 0-1)	207	43	75	46	132	41
Active (score 2-5)	277	57	88	54	189	59
JC virus T antigen							.0004
Negative	285	60	120	71	165	54
Positive	190	40	50	29	140	46

NOTE. Table indicates the proportion of tumors with a specific clinical, pathologic, or molecular feature in all patients or patients with 18q LOH-negative tumors or 18q LOH-positive tumors.

Abbreviations: MSI, microsatellite instability; LOH, loss of heterozygosity; HPFS, Health Professionals Follow-Up Study; NHS, Nurses' Health Study; SD, standard deviation; AJCC, American Joint Committee on Cancer; MSS, microsatellite stable; CIMP, CpG island methylator phenotype; JC, John Cunningham.

^*β-catenin was assessed by immunohistochemistry and activation score was calculated as previously described.³³