Table 2.

ORs and 95% CIs of breast cancer by quartile of urinary 6-sulfatoxymelatonin (aMT6s) level among 890 postmenopausal women

Group and variableQuartile
Urinary aMT6s, ng/mg creatinine<10.210.2-21.421.5-34.2≥34.3
Invasive and in situ cancers combined
No of case patients/No of control subjects107/136109/12866/13475/135
    Simple OR1.01.04 (0.80-1.36)0.75 (0.55-1.02)0.81 (0.60-1.09)0.07
    Multivariable OR1.01.08 (0.73-1.59)0.58 (0.38-0.88)0.62 (0.41-0.95)0.004
Invasive cancers only
No of case patients/No. of control subjects82/11085/10052/10159/103
    Simple OR1.01.08 (0.79-1.46)0.80 (0.56-1.13)0.85 (0.61-1.19)0.11
    Multivariable OR1.01.17 (0.75-1.83)0.70 (0.43-1.12)0.74 (0.46-1.21)0.03
In situ cancers only
No of case patients/No of control subjects25/2624/2814/3316/32
    Simple OR1.00.94 (0.54-1.65)0.61 (0.32-1.17)0.68 (0.36-1.27)0.36
    Multivariable OR1.01.00 (0.36-2.79)0.24 (0.08-0.71)0.23 (0.08-0.69)0.03
  • * We tested for trends by modeling log-transformed aMT6s concentrations continuously and calculating the Wald statistic.

  • Simple conditional logistic regression model.

  • Multivariable conditional logistic regression models adjusted for the following breast cancer risk factors: body mass index in 4 categories (≤23, 23-24.9, 25-28.9, or ≥29 kg/m2), history of benign breast disease (yes or no), family history (mother or sister) of breast cancer (yes or no), smoking history (current smoker, yes or no), age at menarche in 4 categories (<12, 13, 14, or >14 y), age at menopause in 4 categories (≤45, 46-50, 51-53, or >53 y), alcohol consumption (none or less than one drink/day, or 1+ drinks/day), current hormone replacement therapy use (yes or no), parity (nulliparous or 1-2 or 3-4 or ≥5 children), first spot morning urine (yes or no), and current use of antidepressants (yes or no).