Effect of soy isoflavones on breast cancer recurrence and death for patients receiving adjuvant endocrine therapy.
BACKGROUND: The intake of soy isoflavones among women with breast cancer has become a public health concern, because these compounds have weak estrogenic effects. There is little clinical evidence about their safety for patients with breast cancer who are receiving adjuvant endocrine therapy.
METHODS: For patients who underwent surgery for breast cancer between August 2002 and July 2003 and who were receiving adjuvant endocrine therapy, we examined associations between dietary intake of soy isoflavones and recurrence of breast cancer and death. We measured dietary intake of soy isoflavones at baseline using a validated food frequency questionnaire. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) by means of multivariable Cox proportional hazards regression models. We further stratified the analyses by hormonal receptor status and endocrine therapy.
RESULTS: The median follow-up period for the 524 patients in this study was 5.1 years. Among premenopausal patients, the overall death rate (30.6%) was not related to intake of soy isoflavones (HR = 1.05, 95% CI 0.78-1.71 for the highest quartile [> 42.3 mg/day] v. the lowest quartile [< 15.2 mg/day], p for trend = 0.87). Relative to postmenopausal patients in the lowest quartile of soy isoflavone intake, the risk of recurrence for postmenopausal patients in the highest quartile was significantly lower (HR = 0.67, 95% CI 0.54-0.85, p for trend = 0.02). Inverse associations were observed in patients with estrogen and progesterone receptor positive disease and those receiving anastrozole therapy.
结果：524例患者的中位随访时间为5.1年。绝经前患者总死亡率(30.6%)和大豆异黄酮摄入水平无关联(最高四分位水平[> 42.3 mg/day] v.最低四分位水平[< 15.2 mg/day]HR = 1.05, 95% CI 0.78-1.71, 趋势分析p = 0.87)。相对于最低四分位大豆异黄酮摄入水平的绝经后患者，最高四分位大豆异黄酮摄入水平的绝经后患者复发风险显著降低(HR = 0.67, 95% CI 0.54-0.85, 趋势分析p = 0.02)。雌、孕激素受体阳性患者和阿那曲唑治疗患者也出现类似结果。
INTERPRETATION: High dietary intake of soy isoflavones was associated with lower risk of recurrence among postmenopausal patients with breast cancer positive for estrogen and progesterone receptor and those who were receiving anastrozole as endocrine therapy.