Phytonutrients and outcomes following breast cancer: a systematic review and meta-analysis of observational studies

source extracted confidence: high 2026-04-09
#humans #female #prospective-studies #retrospective-studies #breast-neoplasms

Phytonutrients and outcomes following breast cancer: a systematic review and meta-analysis of observational studies

van et al., 2024 | JNCI Cancer Spectr | Meta Analysis

Citation

van Die M Diana, Bone Kerry M, ... Paller Channing J. Phytonutrients and outcomes following breast cancer: a systematic review and meta-analysis of observational studies. JNCI Cancer Spectr. 2024-Jan-04;8(1). doi:10.1093/jncics/pkad104

Abstract

BACKGROUND: Phytonutrient intakes may improve outcomes following breast cancer, but the impact of postdiagnosis introduction vs established prediagnostic exposure as well as optimum doses has not been established. Evidence from observational studies for key exposures was evaluated, including dosage and intake time frames. METHODS: MEDLINE, EMBASE, CINAHL, Cochrane Library, ClinicalTrials.gov, and the ISRCTN registry were searched for prospective and retrospective observational studies investigating the impact of soybean, lignans, cruciferous (cabbage-family) vegetables, green tea, or their phytonutrients on breast cancer survival outcomes. A random-effects model was used to calculate summary hazard ratios (HRs) and 95% confidence intervals (CIs). Nonlinear dose-response analyses were conducted using restricted cubic splines. RESULTS: Thirty-two articles were included. Soy isoflavones were associated with a 26% reduced risk of recurrence (HR = 0.74, 95% CI = 0.60 to 0.92), particularly among postmenopausal (HR = 0.72, 95% CI = 0.55 to 0.94) and estrogen receptor-positive survivors (HR = 0.82, 95% CI = 0.70 to 0.97), with the greatest risk reduction at 60 mg/day. In mortality outcomes, the reduction was mostly at 20 to 40 mg/day. Soy protein and products were inversely associated with cancer-specific mortality for estrogen receptor-positive disease (HR = 0.75, 95% CI = 0.60 to 0.92). An inverse association was observed for serum or plasma enterolactone, measured prediagnosis and early postdiagnosis, with cancer-specific mortality (HR = 0.72, 95% CI = 0.58 to 0.90) and all-cause mortality (HR = 0.69, 95% CI = 0.57 to 0.83). No effects were observed for cruciferous vegetables. There was a 44% reduced risk of recurrence with prediagnostic green tea for stage I and II breast cancer (HR = 0.56, 95% CI = 0.38 to 0.83). CONCLUSIONS: Soy, enterolactone, and green tea demonstrated significant risk reductions in outcomes following breast cancer. Evidence is needed regarding the impact of postdiagnostic introduction or substantial increase of these exposures.

Key Findings

Thirty-two articles were included. Soy isoflavones were associated with a 26% reduced risk of recurrence (HR = 0.74, 95% CI = 0.60 to 0.92), particularly among postmenopausal (HR = 0.72, 95% CI = 0.55 to 0.94) and estrogen receptor-positive survivors (HR = 0.82, 95% CI = 0.70 to 0.97), with the greatest risk reduction at 60 mg/day. In mortality outcomes, the reduction was mostly at 20 to 40 mg/day. Soy protein and products were inversely associated with cancer-specific mortality for estrogen rec

Outcomes Measured

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Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition See abstract

MeSH Terms

  • Humans
  • Female
  • Prospective Studies
  • Retrospective Studies
  • Breast Neoplasms
  • Receptors, Estrogen
  • Tea
  • 4-Butyrolactone
  • Lignans

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Meta-Analysis, Systematic Review, Journal Article
  • Vertical: green-tea

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09