Phytonutrients and outcomes following breast cancer: a systematic review and meta-analysis of observational studies
A partir d'une revue systématique de la littérature (32 articles), cette méta-analyse évalue l'effet d'une consommation d'aliments de nature végétale (soja, lignanes, légumes crucifères/de la famille du chou, thé vert ou leurs phytonutriments) sur la survie des patientes atteintes d'un cancer du sein
Background: Phytonutrient intakes may improve outcomes following breast cancer, but the impact of post-diagnosis introduction vs established pre-diagnostic exposure, and optimum doses, have not been established. Evidence from observational studies for key exposures was evaluated, including dosage and intake timeframes. Methods: MEDLINE, EMBASE, CINAHL, Cochrane Library, ClinicalTrials.gov, ISRCTN registry and ICMJE were searched for prospective and retrospective observational studies investigating soybean, lignans, cruciferous/cabbage-family vegetables, green tea, or their phytonutrients, and breast cancer survival outcomes. A random effects model was used to calculate summary hazard ratios (HRs) and 95% confidence intervals. 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 (0.60–0.92)], particularly among post-menopausal [HR 0.72 (0.55–0.94)] and estrogen-receptor (ER)+ survivors [HR 0.82 (0.70–0.97), with the greatest risk reduction at 60 mg/day. In mortality outcomes, the reduction was mostly at 20-40 mg/d. Soy protein/products were inversely associated with cancer-specific mortality for ER+ disease [HR 0.75 (0.60–0.92)]. An inverse association was observed for serum/plasma enterolactone, measured pre-diagnosis and early post-diagnosis, with cancer-specific mortality [HR 0.72 (0.58–0.90)], and all-cause mortality [HR 0.69 (0.57–0.83]. No effects were observed for cruciferous vegetables. There was a 44% reduced risk of recurrence with pre-diagnostic green tea for stages I-II breast cancer [HR 0.56 (0.38–0.83)]. Conclusions: Soy, enterolactone and green tea demonstrated significant risk reductions in outcomes following breast cancer. Evidence is needed regarding the impact of post-diagnostic introduction or substantial increase of these exposures.
JNCI Cancer Spectrum 2023