Table 1. Baseline characteristics.
| Cases (n = 613) |
Controls (n = 1190) |
Pb | Missing (%) | ||||
|---|---|---|---|---|---|---|---|
| N | Median (IQRa) or % | N | Median (IQRa) or % | ||||
| Participant characteristics | |||||||
| Age at sampling (years) | 613 | 59.8 (40.1–67.8) | 1190 | 59.7 (40.0–67.8) | 0 | ||
| Sex, female | 360 | 59% | 703 | 59% | 0 | ||
| Cohort, VIP | 479 | 78% | 931 | 78% | 0 | ||
| Fasting status | 0 | ||||||
| <4 hours | 141 | 23% | 272 | 23% | |||
| 4–8 hours | 107 | 17% | 202 | 17% | |||
| ≥8 hours | 365 | 60% | 716 | 60% | |||
| Smoking status | 0 | ||||||
| Current | 114 | 19% | 239 | 20% | 0.01 | ||
| Ex- | 136 | 22% | 197 | 17% | |||
| Never | 363 | 59% | 754 | 63% | |||
| Body mass index (BMI, kg/m2) | 591 | 25.7 (23.5–28.2) | 1147 | 25.6 (23.3–28.1) | 0.43 | 4 | |
| Alcohol intake (g/day)c | 385 | 2.4 (0.2–5.8) | 754 | 2.3 (0.3–5.7) | 0.94 | 13c | |
| Recreational physical activityc,d | 3c | ||||||
| 1 | 221 | 45% | 354 | 40% | 0.92 | ||
| 2 | 117 | 25% | 240 | 27% | |||
| 3 | 81 | 17% | 168 | 19% | |||
| 4 | 29 | 6% | 68 | 7% | |||
| 5 | 30 | 7% | 64 | 7% | |||
| Occupational physical activityc,e | 0.94 | 13c | |||||
| 1 | 90 | 21% | 163 | 20% | |||
| 2 | 77 | 18% | 155 | 19% | |||
| 3 | 111 | 27% | 223 | 27% | |||
| 4 | 102 | 25% | 229 | 28% | |||
| 5 | 36 | 9% | 45 | 6% | |||
| eGFR (ml/min/1.73 m2) | 596 | 62.0 (52.3–73.0) | 1149 | 61.7 (50.9–72.3) | 0.48 | 4 | |
| Neopterin (nmol/L) | 608 | 9.7 (8.2–11.9) | 1186 | 9.4 (8.0–11.4) | 0.02 | 0.5 | |
| KTr | 613 | 0.023 (0.019–0.026) | 1190 | 0.022 (0.019–0.026) | 0.23 | 0 | |
| Vitamin supplement usec | 0c | ||||||
| Last 14 days | 32 | 7% | 73 | 8% | 0.49 | ||
| Last year | 40 | 8% | 105 | 11% | 0.11 | ||
| Dietary B-vitamin intakesc,f | |||||||
| Folate (μg/MJ) | 359 | 29.9 (25.3–36.0) | 697 | 29.8 (25.3–36.0) | 0.81 | 6c | |
| Vitamin B6 (mg/MJ) | 359 | 0.27 (0.22–0.31) | 697 | 0.26 (0.23–0.30) | 0.98 | 6c | |
| Vitamin B2 (riboflavin, mg/MJ) | 359 | 0.19 (0.16–0.22) | 697 | 0.19 (0.16–0.22) | 0.38 | 6c | |
| Vitamin B12 (cobalamin, μg/MJ) | 359 | 0.61 (0.46–0.78) | 697 | 0.59 (0.48–0.78) | 0.89 | 6c | |
| Plasma metabolites | |||||||
| Folate (nmol/L) | 613 | 7.3 (4.9–10.4) | 1190 | 7.2 (4.6–10.2) | 0.49 | 0 | |
| Vitamin B6 (PLP, nmol/L) | 608 | 35.9 (25.9–51.5) | 1186 | 38.2 (28.0–51.5) | 0.08 | 0.5 | |
| Vitamin B2 (riboflavin, nmol/L) | 608 | 10.8 (7.4–16.0) | 1186 | 11.8 (7.9–17.9) | 0.002 | 0.5 | |
| Vitamin B12 (cobalamin, nmol/L) | 603 | 413 (337–498) | 1173 | 426 (353–501) | 0.02 | 2 | |
| Homocysteine (μmol/L) | 613 | 10.1 (8.4–11.9) | 1190 | 9.9 (8.2–11.7) | 0.15 | 0 | |
| Cystathionine (μmol/L) | 613 | 0.15 (0.12–0.21) | 1190 | 0.16 (0.12–0.22) | 0.65 | 0 | |
| Cysteine (μmol/L) | 613 | 275 (253–299) | 1190 | 276 (255–298) | 0.74 | 0 | |
| Glycine (μmol/L) | 613 | 227 (194–265) | 1190 | 225 (194–277) | 0.96 | 0 | |
| Serine (μmol/L) | 613 | 108 (96–122) | 1190 | 110 (96–124) | 0.43 | 0 | |
| Methionine (μmol/L) | 613 | 25.9 (23.2–29.1) | 1190 | 26.4 (23.4–29.9) | 0.07 | 0 | |
| Choline (μmol/L) | 606 | 8.6 (7.6–9.7) | 1189 | 8.6 (7.6–9.8) | 0.83 | 0.4 | |
| Betaine (μmol/L) | 606 | 29.9 (25.7–34.4) | 1189 | 30.8 (26.1–35.5) | 0.05 | 0.4 | |
| DMG (μmol/L) | 606 | 3.6 (2.9–4.4) | 1189 | 3.6 (3.0–4.4) | 0.79 | 0.4 | |
| Sarcosine (μmol/L) | 613 | 1.5 (1.1–2.0) | 1190 | 1.5 (1.2–2.1) | 0.54 | 0 | |
| Case characteristics | |||||||
| Age at diagnosis (years) | 613 | 65.2 (59.3–70.2) | 0 | ||||
| Follow-up time (years) | 613 | 8.2 (4.7–11.9) | 0 | ||||
| Tumor site | 0.2 | ||||||
| Right colon | 183 | 30% | |||||
| Left colon | 215 | 35% | |||||
| Rectum | 214 | 35% | |||||
| Tumor stage | 5 | ||||||
| I-II | 308 | 53% | |||||
| III-IV | 276 | 47% | |||||
Abbreviations: PLP, pyridoxal 5′ phosphate – DMG, Dimethylglycine – MJ, Mega Joules – eGFR, estimated glomerular filtration rate (by Cockcroft–Gault formula) – KTr, kynurenine/tryptophan ratio.
aIQR: Interquartile range (25th-75th percentile).
bFrom test for difference in distribution between cases and controls. Mann-Whitney U tests for continuous variables, Chi-square tests for categorical variables. Not calculated for matching variables. Bonferroni-corrected threshold for significance differences among metabolites = 0.05/14 ≈ 0.004.
cVariables available in the VIP cohort only.
dSelf-reported exercise frequency during leisure time on a scale from 1–5, where 1: never; 2: every now and then - not regularly; 3: 1–2 times/week; 4: 2–3 times/week; 5: more than 3 times/week.
eSelf-reported on a scale from 1–5, where 1: sedentary or standing work; 2: light but partly physically active; 3: light and physically active; 4: sometimes physically strenuous; 5: physically strenuous most of the time.
fEstimated from self-administered, semi-quantitative food frequency questionnaires (FFQs) designed to measure intakes during the previous year in mass/day, divided by total energy intake.