Untargeted plasma metabolomics and risk of colorectal cancer—an analysis nested within a large-scale prospective cohort

Table 1 Descriptive statistics of baseline variables in colorectal cancer cases and matched control samples

	Cases (n = 902)	Controls (n = 902)	p-value
Age at baseline	56.2 (7.4)	56.2 (7.4)	0.826
Age at diagnosis	66.5 (9.1)	-	-
Sex			1.000
Men	462 (51.2%)	462 (51.2%)
Women	440 (48.8%)	440 (48.8%)
BMI (kg/m²)^a	26.7 (4.0)	26.3 (4.0)	0.015
Cohort			1.000
VIP	820 (91%)	820 (91%)
MONICA	82 (9%)	82 (9%)
Freeze and thaw cycles^b			< 0.001
0	755 (84%)	752 (83%)
1	79 (9%)	109 (12%)
2	44 (5%)	40 (4%)
3	24 (3%)	1 (0%)
Fasting status			1.000
0–4 h	27 (3%)	27 (3%)
4–8 h	125 (14%)	125 (14%)
> 8 h	750 (83%)	750 (83%)
Storage time (years)	20.9 (5.7)	20.9 (5.7)	0.976
Smoking status			0.221
Nonsmoker	364 (41%)	400 (45%)
Former smoker	335 (38%)	307 (35%)
Current smoker	187 (21%)	173 (20%)
Missing	16	22
Education			0.359
Elementary school	348 (39%)	369 (42%)
Secondary school	397 (45%)	362 (41%)
Postsecondary school	141 (16%)	157 (18%)
Missing	16	14
Diabetes			0.069
Yes	34 (4%)	20 (2%)
No	863 (96%)	872 (98%)
Missing	5	10
Recreational physical activity			0.432
Never	373 (49%)	337 (44%)
Now and then	201 (26%)	212 (28%)
1–2 times/week	98 (14%)	103 (14%)
2–3 times/week	61 (8%)	76 (10%)
> 3 times/week	36 (5%)	30 (4%)
Missing	133	144
Alcohol intake (g/day)^c	4.1 (5.0)	3.8 (4.7)	0.624
Tumor location			-
Proximal colon	286 (32%)	-
Distal colon	266 (30%)	-
Rectum	342 (38%)	-
Missing	8	-
Stage			-
Stages I–II	426 (51%)	-
Stages III–IV	417 (49%)	-
Missing	59	-
BRAF^d			-
Mutation	140 (20%)	-
Wild type	565 (80%)	-
Missing	197	-
KRAS^d			-
Mutation	154 23%)	-
Wild type	504 (77%)	-
Missing	244	-
KRAS/BRAF^d			-
BRAF	140 (22%)	-
KRAS	154 (24%)	-
Both wild type	354 (55%)	-
Missing	254	-
MSI status			-
MSS	568 (87%)	-
MSI	87 (13%)	-
Missing	247	-

BMI body mass index. VIP Västerbotten Intervention Programme. MONICA Multinational Monitoring of Trends and Determinants in Cardiovascular Disease. MSI microsatellite instability. MSS microsatellite stable. Mean value and standard deviation are reported for continuous variable, whereas counts and percentage are presented for categorical variables. P-values were calculated using paired Wilcoxon signed-rank tests or chi-squared tests. ^aCases and controls had 5 and 7 missing values, respectively. ^bPrior to aliquoting for shipment to lab. Of the case–control pairs, 92% were exactly matched on number of freeze–thaw cycles. ^cCases and controls had 98 and 101 missing values, respectively. ^dFour of the missing values were samples with both KRAS and BRAF mutation, which were excluded in the subgroup analysis

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