Table 2.
Relationship between pre-diagnostic circulating tryptophan and kynurenine, and the kynurenine/tryptophan ratio (KTR), by tertiles and continuously, with risk of glioma overall, by gender, and for glioblastoma (GBM).1
| All glioma, overall | All glioma, women | All glioma, men | GBM, overall | |||||
|---|---|---|---|---|---|---|---|---|
|
| ||||||||
| # Gliomas | RR (95%CI) | # Gliomas | RR (95%CI) | # Gliomas | RR (95%CI) | # GBM | RR (95%CI) | |
|
| ||||||||
| Tryptophan, μM | ||||||||
| ≤ 64.33 | 30 | Ref | 22 | Ref | 8 | Ref | 22 | Ref |
| >64.33 to 73.53 | 28 | 0.86 (0.45–1.66) | 14 | 0.49 (0.20–1.21) | 14 | 1.85 (0.65–5.28) | 20 | 0.71 (0.33–1.54) |
| > 73.53 | 26 | 0.80 (0.41–1.55) | 16 | 0.50 (0.21–1.20) | 10 | 1.21 (0.39–3.70) | 12 | 0.52 (0.21–1.26) |
| p-value | 0.50 | 0.13 | 0.70 | 0.14 | ||||
| Continuous | 84 | 0.91 (0.69–1.19) | 52 | 0.68 (0.45–1.03) | 32 | 1.18 (0.79–1.75) | 54 | 0.83 (0.58–1.20) |
|
| ||||||||
| Kynurenine, μM | ||||||||
| ≤ 1.39 | 24 | Ref | 20 | Ref | 4 | Ref | 14 | Ref |
| >1.39–1.70 | 36 | 1.61 (0.83–3.11) | 23 | 1.17 (0.50–2.74) | 13 | 3.46 (1.03–11.69) | 24 | 1.66 (0.75–3.65) |
| > 1.70 | 24 | 1.13 (0.57–2.26) | 9 | 0.47 (0.18–1.21) | 15 | 4.11 (1.12–15.07) | 16 | 1.18 (0.52–2.71) |
| p-value | 0.89 | 0.11 | 0.05 | 0.74 | ||||
| Continuous | 84 | 0.98 (0.74-.28) | 52 | 0.72 (0.48–1.08) | 32 | 1.21 (0.82–1.77) | 54 | 1.03 (0.75–1.40) |
|
| ||||||||
| KTR | ||||||||
| ≤ 0.0210 | 33 | Ref | 22 | Ref | 11 | Ref | 17 | Ref |
| >0.0210 to 0.0243 | 29 | 0.94 (0.49–1.81) | 21 | 1.18 (0.52–2.70) | 8 | 0.58 (0.18–1.85) | 23 | 1.99 (0.83–4.77) |
| > 0.0243 | 22 | 0.74 (0.34–1.59) | 9 | 0.47 (0.15–1.51) | 13 | 0.83 (0.26–2.62) | 14 | 1.05 (0.39–2.79) |
| p-value | 0.46 | 0.34 | 0.84 | 0.87 | ||||
| Continuous | 84 | 1.07 (0.81–1.43) | 52 | 1.07 (0.70–1.63) | 32 | 1.05 (0.70–1.57) | 54 | 1.21 (0.84–1.75) |
Abbreviations: KTR= kynurenine/tryptophan ratio; GBM=glioblastoma; OR=Odds ratio; CI=confidence interval
1
Controls were matched to cases on year of birth (± 1 year; 2 years was used for 10 matched sets), month of blood collection (± 1 month), race (white vs. non-white), and, by study design, gender. Conditional logistic regression models adjusted for body mass index (continuous, kg/m2).