Table 2

Levels of urinary 6β-OHC:cortisol ratios for cases and controls, Shanghai Breast Cancer Study, 1996–98

	Urinary cortisol ratios
	Case	Control	Percentage difference^a	P^b
All of the subjects (246 pairs)^c
Mean ± SD	3.03 ± 1.88	2.54 ± 1.68	19.3	0.001
Median (25^th, 75^th percentile)	2.61 (1.63, 3.92)	2.16 (1.32, 3.28)	20.8	<0.001
Age ≤45 years (102 pairs)^c
Mean ± SD	2.95 ± 1.89	2.72 ± 1.66	8.5	0.33
Median (25^th, 75^th percentile)	2.49 (1.53, 3.85)	2.35 (1.48, 3.59)	6.0	0.45
Age >45 years (144 pairs)^c
Mean ± SD	3.10 ± 1.88	2.42 ± 1.68	28.1	<0.001
Median (25^th, 75^th percentile)	2.64 (1.74, 3.99)	2.01 (1.24, 2.95)	31.3	<0.001

^a Expressed as (mean_cases − mean_controls)/mean_controls or (median_cases − median_controls)/median_controls.
^b Ps were from paired t-test of log-transformed data (for mean comparisons) or the Wilcoxon signed rank test (for median comparisons).
^c Case-control pairs.