SUMMARY Ethnic differences in breast cancer survival have been a long-standing concern. The objective of this review is to present relevant studies for all major U.S. racial/ethnic groups including African Americans, Hispanics, Native Americans, Japanese, and Native Hawaiians, and to discuss underlying causes of disparity. In comparison to Caucasian women, African American women continue to experience the poorest breast cancer specific survival of all ethnic groups in the US. The prognosis for Latinas, Native Hawaiians, and Native Americans is intermediate, better than for African Americans but not as good as for Caucasians, whereas Japanese women tend to have better outcomes. The following possible contributors to the observed differences are discussed in detail: unfavorable distribution of stage at diagnosis due to low screening rates, limited access to care and treatment, tumor type, comorbidities, socioeconomic status, obesity, and physical activity.

In addition to their antiestrogenic effects, soy isoflavones may protect against cancer through alternate biologic actions including antioxidant properties. This randomized, crossover study explored the relation between dietary isoflavone intake through common soy foods and oxidative stress quantified by urinary isoprostane levels. Eighty-two women aged 39.2±6.1 years were randomized to a high soy diet of 2 soy food servings per day and a low soy diet of <3 servings per week for 6 months each, separated by a 1 month washout period. Urine samples were collected at baseline and at the end of each dietary period. Urinary isoprostane levels were measured using enzyme-linked immunosorbent assays (ELISA) and adjusted for creatinine levels. Mixed models using log-transformed values were applied to evaluate the effect of the high soy diet. Unadjusted isoprostane excretion levels were lower during the high than the low soy diet, but this effect was not statistically significant (p=0.81). After adjustment for urinary creatinine, isoprostane excretion was slightly higher during the high soy diet (p=0.02), an observation that was confirmed in a regression analysis between urinary isoflavones and isoprostanes during the high soy diet. The original association remained significant when restricted to adherent participants; however, this effect disappeared after exclusion of three extreme values. In agreement with several previous reports, these findings do not support the hypothesis that soy exerts antioxidant effects as measured by urinary isoprostane excretions, but additional markers of oxidative stress need to be investigated in future studies.