Soy, enterolactone, and green tea are associated with reductions in adverse breast cancer outcomes, according to a systematic review and meta-analysis published in the February issue of JNCI Cancer Spectrum.
M. Diana van Die, Ph.D., from Western Sydney University in Penrith, Australia, and colleagues reviewed prospective and retrospective observational studies examining the impact of soybean, lignans, cruciferous vegetables, green tea, or their phytonutrients on breast cancer survival outcomes. Data were included from 32 studies.
The researchers found that the risk for recurrence was reduced in association with soy isoflavones (hazard ratio, 0.74), especially among postmenopausal and estrogen receptor-positive survivors (hazard ratios, 0.72 and 0.82, respectively), with the greatest reduction in risk seen at 60 mg/day. The reduction was mainly at 20 to 40 mg/day for mortality outcomes. An inverse association was seen for soy protein and soy products with cancer-specific mortality for estrogen receptor-positive disease (hazard ratio, 0.75). Serum or plasma enterolactone, measured prediagnosis and early postdiagnosis, was inversely associated with cancer-specific mortality and all-cause mortality (hazard ratios, 0.72 and 0.69, respectively). There were no effects observed for cruciferous vegetables. Prediagnostic green tea intake was associated with a reduced risk for recurrence for stage I and II breast cancer (hazard ratio, 0.56).
“To further inform clinical practice, evidence is required on the impact of dietary and supplemental intakes of phytonutrients introduced or substantially increased following diagnosis and treatment,” the authors write.
Several authors disclosed ties to industry.
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