Association of Fermented Products with Risk of Cancer Recurrence and Mortality among Breast Cancer Survivors: A Prospective Cohort Study

We hypothesized that the intake of fermented soy and dairy products, but not fermented vegetable products, was associated with reduced cancer recurrence and mortality in breast cancer survivors. Women (n = 606) who underwent dietary survey using a 24-h recall within 3 years of breast cancer surgery were recruited, and were followed up for a mean of 89 mo,. Cox proportional hazards regression analysis showed that the risk of cancer recurrence was inversely associated with the intake of fermented soy products (Hazard ratios (HRs):0.976, 95% confidence intervals (CI):0.95-0.99) and fermented dairy products (HRs:0.992, 95% CI:0.98-0.99). Furthermore, the risk of cancer recurrence was inversely associated with the intake of fermented soy products in hormone receptor-positive (HRs:0.296, 95% CI:0.11-0.79), estrogen receptor-positive (HRs:0.971, 95% CI:0.94-0.99), and progesterone receptor-positive (HRs:0.972, 95% CI:0.94-0.99) patients. Mortality was inversely associated with the intake of fermented soy products (HRs:0.967, 95% CI:0.93-0.99). Disease-free survival (P = 0.001) and overall survival (P = 0.004) were positively associated with intake of fermented soy products. Intake of fermented vegetable products had no significant effect on cancer recurrence or mortality. This study suggests that the intake of fermented soy and dairy could be beneficial in preventing cancer recurrence.