Table 2.
Overall and subgroup analyses of the association between soy isoflavones, protein and products, lignans, serum/plasma enterolactone concentrations, cruciferous vegetables, and green tea with breast cancer recurrence, breast cancer–specific mortality, and all-cause mortality
| Exposure and outcome | Subgroup | Total subgroup cohort, No. | Studies, No. | High vs low analysis |
||
|---|---|---|---|---|---|---|
| Hazard ratio (95% confidence interval) | I 2 (%) | P for heterogeneity | ||||
| Soy isoflavones | ||||||
| Recurrence | Overall | 11 837 | 4 | 0.74 (0.60 to 0.92)a | 58.3 | .07 |
| Prediagnosis | 2323 | 3 | 0.82 (0.58 to 1.15) | 44.9 | .16 | |
| Postdiagnosis | 10 974 | 2 | 0.85 (0.46 to 1.59) | 82.1 | .02 | |
| Premenopausal | 5179 | 3 | 0.92 (0.74 to 1.14) | 0 | .94 | |
| Postmenopausal | 5971 | 3 | 0.72 (0.55 to 0.94)a | 45.8 | .16 | |
| Estrogen receptor positive | 8152 | 3 | 0.82 (0.70 to 0.97)a | 0 | .67 | |
| Estrogen receptor negative | 3139 | 3 | 0.93 (0.60 to 1.44) | 61.7 | .07 | |
| Tamoxifen | 6249 | 3 | 0.79 (0.55 to 1.14) | 50.7 | .13 | |
| No tamoxifen | 2333 | 2 | 1.02 (0.57 to 1.84) | 66.5 | .08 | |
| Breast cancer–specific mortality | Overall | 29 817 | 7 | 0.88 (0.75 to 1.04) | 30.9 | .19 |
| Prediagnosis | 19 975 | 7 | 0.92 (0.73 to 1.16) | 51.0 | .07 | |
| Postdiagnosis | 10 974 | 2 | 0.88 (0.52 to 1.49) | 58.8 | .12 | |
| Premenopausal | 7342 | 3 | 0.90 (0.67 to 1.21) | 0 | .67 | |
| Postmenopausal | 29 817 | 3 | 0.92 (0.77 to 1.10) | 0 | .69 | |
| Estrogen receptor positive | 14 260 | 4 | 0.81 (0.65 to 1.02) | 15.0 | .32 | |
| Estrogen receptor negative | 4913 | 4 | 0.77 (0.60 to 0.98)a | 0 | .81 | |
| All-cause mortality | Overall | 34 567 | 7 | 0.88 (0.77 to 0.997)a | 36.1 | .15 |
| Prediagnosis | 23 587 | 6 | 0.88 (0.75 to 1.04) | 29.8 | .21 | |
| Postdiagnosis | 12 440 | 3 | 0.81 (0.64 to 1.03) | 11.0 | .33 | |
| Premenopausal | 11 415 | 6 | 0.96 (0.81 to 1.14) | 0 | .78 | |
| Postmenopausal | 22 801 | 7 | 0.88 (0.76 to 1.02) | 29.5 | .20 | |
| Estrogen receptor positive | 15 496 | 4 | 0.96 (0.79 to 1.16) | 0 | .95 | |
| Estrogen receptor negative | 6212 | 4 | 0.93 (0.72 to 1.22) | 0 | .82 | |
| Stages I-II | 5334 | 2 | 1.22 (0.68 to 2.18) | 0 | .39 | |
| Stages III-IV | 780 | 2 | 0.58 (0.39 to 0.87)a | 0 | .43 | |
| Tamoxifen | 8673 | 3 | 0.81 (0.64 to 1.01) | 0 | .51 | |
| No tamoxifen | 5705 | 3 | 0.78 (0.62 to 0.98)a | 4.4 | .35 | |
| Soy protein and products | ||||||
| Recurrence (products) | Overall | 945 | 2 | 0.48 (0.23-0.99)a | 25.4 | .25 |
| Breast cancer–specific mortality | Overall | 5866 | 3 | 0.92 (0.76-1.11) | 0 | .41 |
| Premenopausal | 951 | 1 | 1.09 (0.74-1.60) | —c | —c | |
| Postmenopausal | 4299 | 2 | 0.93 (0.69 to 1.25) | 0 | .39 | |
| Estrogen receptor positive | 2604 | 3 | 0.75 (0.60 to 0.92)a | 0 | .90 | |
| Estrogen receptor negative | 991 | 3 | 0.93 (0.49 to 1.78) | 64.2 | .06 | |
| All-cause mortality | Overall | 9480 | 3 | 0.77 (0.49 to 1.21) | 74.3 | .02 |
| Estrogen receptor positive | 4928 | 2 | 0.78 (0.50 to 1.21) | 59.1 | .12 | |
| Estrogen receptor negative | 2266 | 2 | 1.10 (0.51 to 2.37) | 76.3 | .04 | |
| Lignans | ||||||
| Breast cancer–specific mortality | Overall | 14 052 | 3 | 0.91 (0.74 to 1.12) | 55.8 | .10 |
| Premenopausal | 3486 | 3 | 1.55 (1.01 to 2.39)b | 0 | .70 | |
| Postmenopause | 10 566 | 3 | 0.66 (0.42 to 1.03) | 47.0 | .15 | |
| All-cause mortality | Overall | 14 114 | 3 | 0.95 (0.81 to 1.12) | 0 | .65 |
| Premenopause | 3495 | 3 | 1.59 (1.11 to 2.26)b | 0 | .68 | |
| Postmenopause | 10 619 | 3 | 0.81 (0.61 to 1.09) | 40.3 | .19 | |
| Enterolactone | ||||||
| Recurrence | Overall | 3295 | 2 | 0.91 (0.67 to 1.23) | 17.2 | .27 |
| Breast cancer–specific mortality | Overall | 3864 | 3 | 0.72 (0.58 to 0.90)a | 0 | .57 |
| Prediagnosis | 1457 | 1 | 0.74 (0.55 to 0.99)a | —c | —c | |
| Postdiagnosis | 2407 | 2 | 0.70 (0.50 to 0.98)a | 5.7 | .30 | |
| Premenopause | 88 | 1 | 1.77 (0.46 to 6.84) | —c | —c | |
| Postmenopause | 3776 | 3 | 0.66 (0.53 to 0.84)a | 0 | .49 | |
| All-cause mortality | Overall | 3864 | 3 | 0.69 (0.57 to 0.83)a | 0 | .59 |
| Prediagnosis | 1457 | 1 | 0.74 (0.59 to 0.93)a | —c | —c | |
| Postdiagnosis | 2407 | 2 | 0.61 (0.45 to 0.83)a | 0 | .76 | |
| Premenopause | 88 | 1 | 1.85 (0.49 to 6.96) | —c | —c | |
| Postmenopause | 3776 | 3 | 0.65 (0.51 to 0.82)a | 22.7 | .27 | |
| Estrogen receptor positive | 2652 | 2 | 0.75 (0.56 to 1.00) | 0 | .93 | |
| Estrogen receptor negative | 609 | 2 | 0.55 (0.28 to 1.08) | 36.1 | .21 | |
| Node positive | 721 | 2 | 0.84 (0.55 to 1.28) | 0 | .74 | |
| Node negative | 1583 | 2 | 0.41 (0.24 to 0.70)a | 0 | .42 | |
| Cruciferous vegetables | ||||||
| Recurrence | Overall (pooled analysis) | 11 390 | 1 | 1.09 (0.92 to 1.30) | —c | —c |
| Breast cancer–specific mortality | Overall | 15 831 | 2 | 1.07 (0.91 to 1.26) | 0 | .59 |
| All-cause mortality | Overall | 17 041 | 3 | 0.99 (0.89 to 1.11) | 0 | .96 |
| Prediagnosis | 1210 | 1 | 0.96 (0.64 to 1.43) | —c | —c | |
| Postdiagnosis | 15 831 | 2 | 1.00 (0.89 to 1.12) | 0 | .83 | |
| Green tea | ||||||
| Recurrence | Overall | 1632 | 2 | 0.74 (0.55 to 1.01) | 0 | .68 |
| Stages I-II | 1398 | 2 | 0.56 (0.38 to 0.83)a | 0 | .98 | |
| Stage III-IV | 234 | 2 | 1.32 (0.62 to 2.79) | 25.7 | .25 | |
a
Significant risk reductions.
b
Significant increase in risk.
c
Value not available (individual study result).