Table II.
Urinary levels of total NNN, free NNN and NNN-N-Gluc and the percentage of NNN-N-Gluc by esophageal cancer status among current smokers, The Shanghai Cohort Study 1986–2008
| Cases (n = 77) | Controls (n = 223) | Pa | |
| Total NNN (fmol/mg creatinine) | 118 (89.1–156)b | 45.1 (38.3–53.1)b | <0.001 |
| Free NNN (fmol/mg creatinine) | 58.2 (43.0–78.7)b | 18.2 (15.3–21.8)b | <0.001 |
| NNN-N-Gluc (fmol/mg creatinine) | 49.8 (37.5–66.1)b | 24.4 (20.6–28.8)b | 0.004 |
| Percentage of NNN-N-Gluc (%) | 46.7 (43.1–50.3)c | 56.4 (54.2–58.5)c | <0.000 |
a
Two-sided P values and means were derived from analysis of variance models retaining matched case–control sets, of which controls were matched with index cases on current smoking status, age, neighborhood and year and month of urine collection.
b
Geometric mean (95% CI).
c
Arithmetic mean (95% CI).