Purpose Racial/ethnic disparities in cancer survival in the United States are well documented, but the underlying causes are not well understood. We quantified the contribution of tumor, treatment, hospital, sociodemographic, and neighborhood factors to racial/ethnic survival disparities in California. Materials and Methods California Cancer Registry data were used to estimate population-based cancer-specific survival for patients diagnosed with breast, prostate, colorectal, or lung cancer between 2000 and 2013 for each racial/ethnic group (non-Hispanic black, Hispanic, Asian American and Pacific Islander, and separately each for Chinese, Japanese, and Filipino) compared with non-Hispanic whites. The percentage contribution of factors to overall racial/ethnic survival disparities was estimated from a sequence of multivariable Cox proportional hazards models. Results In baseline models, black patients had the lowest survival for all cancer sites, and Asian American and Pacific Islander patients had the highest, compared with whites. Mediation analyses suggested that stage at diagnosis had the greatest influence on overall racial/ethnic survival disparities accounting for 24% of disparities in breast cancer, 24% in prostate cancer, and 16% to 30% in colorectal cancer. Neighborhood socioeconomic status was an important factor in all cancers, but only for black and Hispanic patients. The influence of marital status on racial/ethnic disparities was stronger in men than in women. Adjustment for all covariables explained approximately half of the overall survival disparities in breast, prostate, and colorectal cancer, but it explained only 15% to 40% of disparities in lung cancer. Conclusion Overall reductions in racial/ethnic survival disparities were driven largely by reductions for black compared with white patients. Stage at diagnosis had the largest effect on racial/ethnic survival disparities, but earlier detection would not entirely eliminate them. The influences of neighborhood socioeconomic status and marital status suggest that social determinants, support mechanisms, and access to health care are important contributing factors.

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After accounting for patient and clinical characteristics, survival disparities for men with prostate cancer and women with lung or colorectal cancer increased significantly over time, reflecting a lack of improvement in survival for patients with other public or no insurance. To mitigate these growing disparities, all patients with cancer need access to health insurance that covers all the necessary elements of health care, from prevention and early detection to timely treatment according to clinical guidelines.

The finding that greater consumption of a plant-based dietary pattern is associated with a reduced breast cancer risk, particularly for ER-PR- tumors, offers a potential avenue for prevention.

Dietary phytochemical compounds, including isoflavones and isothiocyanates, may inhibit cancer development but have not yet been examined in prospective epidemiologic studies of ovarian cancer. The authors have investigated the association between consumption of these and other nutrients and ovarian cancer risk in a prospective cohort study. Among 97,275 eligible women in the California Teachers Study cohort who completed the baseline dietary assessment in 1995-1996, 280 women developed invasive or borderline ovarian cancer by December 31, 2003. Multivariable Cox proportional hazards regression, with age as the timescale, was used to estimate relative risks and 95% confidence intervals; all statistical tests were two sided. Intake of isoflavones was associated with lower risk of ovarian cancer. Compared with the risk for women who consumed less than 1 mg of total isoflavones per day, the relative risk of ovarian cancer associated with consumption of more than 3 mg/day was 0.56 (95% confidence interval: 0.33, 0.96). Intake of isothiocyanates or foods high in isothiocyanates was not associated with ovarian cancer risk, nor was intake of macronutrients, antioxidant vitamins, or other micronutrients. Although dietary consumption of isoflavones may be associated with decreased ovarian cancer risk, most dietary factors are unlikely to play a major role in ovarian cancer development.