Table 2.

Isoflavone intake and breast cancer risk in low-consuming populations

Authors [Ref.]	Study design	Subjects, n	Results (95% CI)	Comments
Wu et al. [35]	meta-analysis of 11 studies (7 case-control, 4 cohort)	8,533 cases, 8596 controls; cohort of 170,693 women	OR 1.04 (0.97–1.11)	≥ 0.8 mg vs. 0.15 mg daily isoflavone intake
	only case-control studies	6807 cases, 8596 controls	OR 1.02 (0.95–1.11)
	only cohort studies	1726 cases; cohort of 170,693 women	OR 1.08 (0.95–1.24)
Cutler et al. [39]	cohort study	2,529 cases; cohort of 34,708 postmenopausal women	not available	≥ 0.52 mg vs. ≤ 0.13 mg daily isoflavone intake; no significant difference for isoflavone intake
Hedelin et al. [40]	cohort study	1,014 cases; cohort of 45,448 women	RR 0.98 (0.83–1.17)	highest vs. lowest quartile of isoflavone intake (< 0.1 mg/day)
Travis et al. [41]	cohort study	585 cases; cohort of 37,643 women	HR 1.17 (0.79–1.71)	≥ 20 mg vs. < 10 mg daily isoflavone intake; only 29 cases with intake ≥ 20 mg
Ward et al. [42]	nested case-control study	237 cases, 952 controls out of 14,032 women	OR 1.08 (1.00–1.06)	high vs. low levels of urine isoflavones, results are inconsistent with the nonsignificant difference of isoflavone plasma levels
Verheus et al. [43]	nested case-control study	383 cases, 383 controls	OR 0.68 (0.47–0.98)	highest vs. lowest tertile of plasma levels of genistein, effect is stronger in postmenopausal women

CI = Confidence interval; OR = odds ratio; RR = risk ratio; HR = hazard ratio.