Enterolactone concentrations and prognosis after postmenopausal breast cancer: Assessment of effect modification and meta-analysis
Menée à partir d'échantillons sanguins prélevés sur 2 182 patientes ménopausées atteintes d'un cancer du sein (âge : 50 à 74 ans) et à partir d'une méta-analyse (5 études), cette étude évalue, en fonction des caractéristiques tumorales au diagnostic et du mode de vie des patients, l'association entre la concentration d'entérolactone, un métabolite issu de la dégradation des lignanes par la flore intestinale, et la mortalité spécifique ou la mortalité toutes causes confondues
We previously reported that high concentrations of enterolactone, a lignan metabolite, are associated with lower mortality in 1,140 breast cancer patients from Germany. Using an extended set of 2,182 patients aged 50–74 years at diagnosis (2001–2005) and prospectively followed up until 2009, we investigated whether the association with mortality differs by lifestyle factors and tumor characteristics. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using multivariable Cox regression. Potential differential effects by tumor characteristics and lifestyle factors were assessed and a meta-analysis of five studies addressing lignan exposure and breast cancer prognosis was performed to summarize evidence. Median enterolactone concentrations were 17.4 (±30.5 standard deviation) and 22.9 nmol L−1 (±44.8), respectively, for 269 deceased and 1,913 patients still alive. High enterolactone concentrations were significantly associated with lower all-cause mortality (per 10 nmol L−1: HR 0.94, 95% CI 0.90–0.98), breast cancer-specific mortality (HR 0.94, 0.89–0.99), and distant disease-free survival (HR 0.94, 0.90–0.98). Associations were found for stage 0–IIIA but not for stage IIIB–IV disease (phet = 0.01) and were stronger in patients with BMI <25 kg m−2 than those with BMI ≥25 (phet = 0.04). In patients with healthy lifestyle (BMI <25, nonsmoker, physically active), the inverse association with all-cause mortality was still apparent (HR 0.92, 0.85–0.99). The meta-analysis yielded significant associations both for all-cause (HR 0.57, 0.42–0.78) and breast cancer-specific mortality (HR 0.54, 0.39–0.75). Our findings show that high lignan exposure is associated with reduced mortality in breast cancer patients. The inverse association observed in this study cannot be entirely explained by a healthy lifestyle.