Kolb and colleagues present an overview of a vast and complex subject—the disparities in cancer care among racial and ethnic minorities in the United States. Minority health and health disparities have been of interest in this country due to increasing appreciation of (and concern about) differences in cancer outcome. Indeed, there are distinct racial and ethnic differences in cancer incidence and mortality. A significant reason for these disparities is the fact that there are differences in the amount and quality of both preventive and treatment services that some populations receive.
Comparison of cancer incidence and mortality rates is the most accurate way to measure the burden of cancer and detect population disparities. In general, black Americans have cancer incidence and mortality rates higher than whites, and whites have rates higher than Hispanics. Over time, Hispanic rates are expected to rise. Survival statistics, especially 5-year survival rates, are not good measures of cancer burden disparities between populations. While there are often differences in cancer survival, lead time biases associated with the differences in screening rates and earlier diagnosis skew survival statistics.
Populations can be defined by race or ethnicity; they can also be defined by socioeconomic status. The Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute (NCI) has demonstrated that residents of poorer areas of the United States tend to present with more advanced-stage disease and have increased rates of most cancers. Residents of poorer areas also have higher mortality rates from virtually every cancer. Even within racial groups, the poor have worse outcomes compared to the wealthy. Poor whites do worse than wealthier whites, poor blacks do worse than wealthier blacks, and poor Hispanics do worse than wealthier Hispanics. As director of the NCI in the early 1990s, Sam Broder said, "Poverty is a carcinogen." Minorities (both Hispanics and blacks) are disproportionately poor compared to whites. It is worth noting that the absolute number of poor whites is larger than the absolute number of poor blacks and Hispanics combined.
Breast Cancer Data
The authors of this review frequently use breast cancer as an example. This is appropriate, as more is understood about breast cancer disparities than any other disease. Breast cancer is unusual among other cancers in that the incidence among white women is higher than that among black women, yet the black mortality rate is higher than that of whites. Breast cancer incidence among whites may be more than incidence among blacks due to differences in socioeconomic status and behaviors associated with socioeconomic status. Compared to blacks, a larger proportion of whites have certain breast cancer risk factors. An increased proportion of whites have a first live birth after age 30, disproportionately greater use of oral contraceptives, and disproportionately greater use of hormone replacement therapy. These habits or lifestyle choices may increase the risk of less aggressive, more treatable low-grade breast cancers.
On the other hand, dramatic increases in the proportion of black women who have significant weight gain over the past 30 years may mean that an increasing proportion of black women have acquired a greater risk for more aggressive breast cancer. This may be the reason for the rising breast cancer mortality rates among blacks in the late 1980s and early 1990s. The prevalence of black women with higher body mass index outpaced the increase among white women over the past 30 years. Among women, weight gain has been associated with an increased risk for breast cancer and an increased risk for higher grade, more aggressive breast cancer.
Weight gain is also associated with increased risks of diabetes mellitus, hypertension, and cardiac disease. These are significant comorbid disease factors that interfere with the provision of adequate high-quality cancer care. Evidence suggests that weight gain is associated with the development of prostate cancer and other cancers among all races. There is also evidence that increased weight gain is a complicating factor in the care of Hispanic-Americans.
In some cancers, evidence suggests that poverty is correlated with the presentation of more aggressive disease within a given stage. The poor tend to present with more advanced disease, and presentation is delayed after appreciation of symptoms. Of course, higher-grade and more advanced cancer portends disease that is less likely to be effectively treated.