Table 3.
Average levels of smoking intensity and duration and urinary metabolites of cigarette smoke constituents by CYP2A6 genotypes-predicted metabolizers status among control subjects, The Singapore Chinese Health Study 1993–2014
| Smoking related variables | CYP2A6 genotype predicted metabolizer statusa | P for trend | |||
|---|---|---|---|---|---|
| Normal | Intermediate | Slow | Poor | ||
| Number of subjects (%) | 19 (9.6) | 41 (20.8) | 80 (40.6) | 57 (28.9) | |
| Number of cigarettes/day, mean (SD) | 15.4 (11.2) | 19.7 (11.4) | 13.6 (8.5) | 14.1 (10.1) | 0.052 |
| Age start smoking (years), mean (SD) | 18.9 (6.3) | 20.1 (5.9) | 20.4 (6.5) | 20.1 (6.6) | 0.600 |
| Number of years of smoking, mean (SD) | 38.9 (10.6) | 39.0 (9.4) | 36.5 (12.0) | 36.4 (11.8) | 0.210 |
| Pack-years of smoking, mean (SD) | 31.3 (23.1) | 39.7 (23.6) | 27.1 (18.8) | 27.1 (21.6) | 0.031 |
| Urinary biomarkersb | |||||
| Total nicotine (nmol/mg creatinine) | 9.4 (5.8–15.1) | 7.5 (5.4–10.3) | 7.1 (5.6–8.9) | 8.3 (6.3–10.9) | 0.883 |
| Total cotinine (nmol/mg creatinine) | 14.2 (9.8–20.8) | 11.9 (9.2–15.4) | 11.2 (9.3–13.4) | 8.3 (6.7–10.3) | 0.008 |
| Total 3HC (nmol/mg creatinine) | 22.5 (14.6–34.8) | 16.2 (12.0–21.8) | 11.3 (9.2–14.0) | 3.1 (2.4–4.0) | <0.001 |
| TNE (nmol/mg creatinine)c | 49.5 (34.7–70.5) | 37.6 (29.5–47.8) | 31.6 (26.6–37.6) | 23.1 (18.8–28.4) | <0.001 |
| Total NNAL (pmol/mg creatinine)d | 1.16 (0.80–1.66) | 0.94 (0.72–1.22) | 0.96 (0.80–1.16) | 0.74 (0.60–0.92) | 0.042 |
| Free NNAL (pmol/mg creatinine)d | 0.40 (0.26–0.60) | 0.30 (0.24–0.40) | 0.34 (0.28–0.40) | 0.26 (0.20–0.32) | 0.090 |
| NNAL-Glucs (pmol/mg creatinine)d | 0.72 (0.48–1.08) | 0.60 (0.46–0.80) | 0.60 (0.48–0.72) | 0.44 (0.34–0.54) | 0.022 |
| NNAL-N-Gluc (pmol/mg creatinine)d | 0.12 (0.08–0.20) | 0.14 (0.12–0.20) | 0.12 (0.10–0.16) | 0.10 (0.08–0.14) | 0.151 |
| NNAL-O-Gluc (pmol/mg creatinine)d | 0.58 (0.40–0.88) | 0.46 (0.34–0.60) | 0.44 (0.36–0.54) | 0.34 (0.26–0.42) | 0.017 |
| NNAL-Glucs:TNE ratio (pmol/µmol)d | 14.5 (10.2–20.6) | 15.5 (12.1–19.7) | 18.5 (15.6–22.0) | 18.5 (15.0–22.8) | 0.138 |
| NNAL-Glucs:free NNAL ratiod | 1.80 (1.38–2.36) | 1.88 (1.56–2.28) | 1.76 (1.54–2.00) | 1.62 (1.38–1.92) | 0.314 |
3HC, trans-3′-hydroxycotinine; NNAL, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol; NNAL-Glucs, NNAL glucuronides; NNAL-N-Gluc, NNAL N-glucuronide; NNAL-O-Gluc; NNAL O-glucuronide; SD, standard deviation; TNE, total nicotine equivalents.
aSee the Materials and Methods and Supplementary Table 1, available at Carcinogenesis Online, for the CYP2A6 grouping.
bGeometric mean (95% confidence interval).
cThe sum of total nicotine, total cotinine and total 3HC.
dNumber of subjects excluded from analysis due to missing data: 6 for NNAL, NNAL-Glucs, and NNAL-N-Gluc; 12 for NNAL-O-Gluc and 4 for free NNAL.