Introduction to Cancer Disparities: The Scope of the Problem and Possible Solutions

The Birth of a Discipline

In 1973, a landmark paper was published documenting the increasing disparities in cancer mortality between Black and White Americans (Henschke et al., 1973). In many ways, this paper was inspired by the U.S. Civil Rights Movement. It was the signal that the struggle for racial equality was broadening beyond social and economic equality to include equality in health care. The Henschke paper and similar papers related to other diseases would eventually be the start of the academic discipline known as "minority health." Over time, the field become known as "special populations" and later—in the mid-1990s, with the wisdom of then Surgeon General Dr. David Satcher—it became known as "health disparities" (Nkwa-Mullan et al., 2010). The name "health disparities" was descriptive of the field. The phrase was less open to criticism from politicians who did not support programs and research in minority health or special populations. It became difficult for a politician to stand up and speak up against programs intended to reduce disparities in health. Today, there is a movement toward calling the field "health equity." The documentation of disparities in race and the expansion of the discipline became a significant influence on the current health care debate.

The basic principle behind health disparities is the reality that there are populations that do not do as well as others in terms of health outcomes. Initially, those focusing on minority health were physicians who recognized racial differences in presentation of disease and mortality. As the academic field grew, it attracted the talents of professionals in diverse medical disciplines, epidemiologists, and social scientists. Anthropologists helped define populations, and nursing scientists and the palliative care movement helped expand the field further by better defining disparities and expanding the measures of disparities. Patient advocacy was equally important in the birthing of the field. In the 1980s, Congress legislated establishment of the National Institutes of Health (NIH) Office for Research on Minority Health and the Department of Health Education and Welfare (later the Department of Health and Human Services) Office of Minority Health. Eventually, almost every federal health agency opened an office for special populations and, later, an office for health disparities. Provisions within the NIH Revitalization Act of 1993 strengthened research into the field (Freedman et al., 1995) and in 2010, the Affordable Care Act transformed the NIH Office for Research on Minority Health into an institute, with the ability to fund grants and programs across the country. Cancer was one area where the disparities in screening and treatment were clearly documented (Greenberg, Weeks, & Stain, 2008). In an effort to address this, Congress passed legislation creating the Centers for Disease Control (CDC) Breast and Cervical Cancer Treatment Program, to give poor women access to breast and cervical cancer screening.


At one time, the only disparate outcomes discussed were differences in incidence and mortality among Blacks and Whites. Today, our concern for health disparities and achieving health equity has expanded beyond concern for the health of African Americans. During his tenure as volunteer president of the American Cancer Society in 1989, Harold Freeman brought tremendous focus on the fact that America’s poor, be they Black, White, Hispanic, Asian, or Native American, have disparate cancer outcomes. In the early 1990s, National Cancer Institute director Sam Broder made a now famous statement that "poverty is a carcinogen." This led to studies of the effects of poverty and social deprivation on the cause and course of malignant disease. Health disparities research dramatically increased in the field of oncology (Freeman, 1998). Significant advances have been made in defining the scientific and political issues that cause disparities in health, and the interventions (public health, medical, and sociopolitical) that can alleviate such disparities and lead to health equity. Much can be learned through comparing and contrasting well-defined populations. Efforts to determine why one cohort has a low rate of a cancer can help us find interventions to lower that rate in other populations.


The development of cancer databases and registries has increased the availability of data and helped to define disparities through assessment of other outcomes and in other populations. The CDC National Center for Health Statistics (NCHS), established in the early 1960s, began providing state-by-state mortality data. Eventually, NCHS began the National Health Interview Survey (NHIS) and the Behavioral Risk Factor Surveillance System (BRFSS) to provide additional data (Cyrus-David, King, Bevers, & Robinson, 2009). The NCI Surveillance, Epidemiology, and End Results (SEER) Program was launched in 1972 as part of the implementation of the National Cancer Act. It provided incidence and 5-year survival data. As its data matured, additional outcomes measures became available. Researchers began looking at practice patterns data and even geographic differences. In the early 1990s, the NCI SEER program went beyond publishing Black-White data and began publishing data for the five racial and ethnic categories as defined by the U.S. Office of Management and Budget (OMB). The National Cancer Data Base (NCDB) was launched in the late 1980s. It is run by the American College of Surgeons Commission on Cancer and supported by the American Cancer Society. The NCDB registry has grown to include hospitals that treat more than 70% of Americans with cancer. It gathers such demographic data as insurance status and time to treatment received, thereby allowing additional analysis of differences in quality of treatment. Questions addressed include the proportion with a specific disease not receiving standard care and differences in quality of treatment (Fry, Menck, & Winchester, 1996). Recently, quality of life for cancer patients and cancer survivors (pediatric and adult) has become a concern in the health disparities community. Focus areas include the availability of adequate pain control, as well as access to programs for physical and emotional rehabilitation (Lafleur, Said, McAdam-Marx, Jackson, & Mortazavi, 2007).


If we are to truly attack disparities in health outcomes, we must be open minded, question the standard prejudices and paradigms, and carefully define the scientific and medical questions that need to be addressed. Key to defining the problem has been adequately categorizing populations, identifying the outcomes that are disparate, defining how to measure those outcomes, and defining the causes of disparities. Only then can we identify the interventions necessary to overcome the disparities (Brawley & Berger, 2008). Today, we recognize that there are numerous ways to define  populations. Categories frequently used include race, ethnicity, and area of geographic origin or socioeconomic status. There are significant cautions that need to be taken when defining populations using these categories. These are words whose meaning and history are not well understood by the lay and medical public, and they are frequently used with differing meanings. Our race-based labels crudely predict for groups of people that are less likely to do well with cancer and other diseases, but we must realize the sociopolitical nature of these categories (Witzig, 1996). Race is not a biologic categorization. In the assessment of risk of cancer, a form of "benevolent racial profiling" is sometimes appropriate; however, overcommitment to this view without deep, careful thought can obscure the truth and actually impede science from benefiting disparate populations.

The concept of race originated in the eighteenth century. It has to do with superficial facial features and presumed geographic area of origin. It does not even deal with skin color, as dark-skinned people from the Indian subcontinent are considered Caucasian. There are no distinct races, and racial groups are overlapping populations (Brown, 2007). The one "drop rule" in which a person with just one known African ancestor is considered Black is still practiced in this country and is the ultimate example of how unscientific the concept of race is. Many who describe themselves as Black or African American are actually a mixture of European and African ancestries (Witzig, 1996). Ethnicity involves culture, habit, lifestyle, and behavioral patterns and other environmental influences that can cause disease or even lower the risk of disease (Faulkner and Merritt, 1998). Ethnicity defines foods consumed and how foods are prepared. Different ethnic groups often have different attitudes toward health and medical care. They interact differently with medical professionals. Appreciation of this is important to health care professionals who want to provide appropriate care. Ethnicity is appreciated as distinctly different from race. Both are important in cancer causation. Hispanic is an ethnicity. An individual can be categorized as Black race and Hispanic ethnicity or White race and Hispanic ethnicity. Ethnicity might be a bit more scientific than race, even though it is not necessarily static. Some people identify themselves as belonging to a particular ethnic group in one context, and to another in a different context .The racial and ethnic categories used in most U.S. health care data are defined by the OMB. These definitions are used in the U.S. Census. The census data is then used to determine the size of the population in calculating rates of disease. In their directive defining race and ethnicity, OMB notes that the categories are sociopolitical in nature and not based in science.

Area of geographic origin is another way of categorizing populations. It can loosely correlate with ethnicity and race, but tends to be more specific than race. When asked about area of origin, Americans of Korean and African ancestry are more likely to identify as Korean and African, whereas racially they might consider themselves Black or African American.

Socioeconomic status (SES) is a category that often correlates with health status. Its definition has also evolved over time; SES was once defined by household income or education and occupation (Albano et al., 2007). Today, we recognize that insurance status and even degree of medical sophistication are important factors in outcomes. European social scientists have taken SES to a higher level, with deprivation indices that in some cases even take into account whether one has indoor plumbing or household help (Byers et al., 2008). SES can be highly correlated with differences in outcome and related to unknown environmental influences that cause cancer, cause a delay in diagnosis of cancer, or cause less than optimal treatment of cancer. Access to care and lack of convenient care are SES-based variables that play a tremendous role in disparities in the United States (Faggiano, Partanen, Kogevinas, & Boffetta, 1997). SES is also related to the quality and types of foods consumed, the neighborhood and environment one lives in, and the work one does (Faggiano et al., 1997). Numerous surveys suggest that poor Americans are more likely to have harmful health behaviors and less likely to practice healthy behaviors. The poor are more likely to consume higher-calorie diets and have diets higher in carbohydrates and fats. Poor Americans are also more likely to be overweight or obese, and less likely to consume diets high in fruits and vegetables, compared to middle-and upper-middle-class Americans (Satia-Abouta, Patterson, Neuhouser, & Elder, 2002).

Area of residence, too, can be a factor in cancer risk. In the United States, area of residence can be viewed as rural versus urban, with differing access to health care. It can include living in polluted areas with greater exposure to disease-causing chemicals, such as a landfill or an industrial area (Law & Morris, 1998). It can also include living in crime-ridden inner-city neighborhoods, where opportunities for healthful habits such as exercise are limited (Bennett et al., 2007; Gaskin, Price, Brandon, & Laveist, 2009).

These categories can overlap and make attribution of cause of disease difficult.An outcome caused by low SES in a group of Blacks might be mistaken as being due to race or to area of residence. It could also be truly related to all three (Kaufman, Cooper, & McGee, 1997). A higher proportion of Americans of African heritage are poor compared to Whites. It is appropriate to ask what the effect of poverty is on our race-based health statistics. Indeed, socioeconomic status and its incumbent environmental influences may be the cause of many health disparities. It is possible that socioeconomic factors that act largely through and are associated with race are responsible for much of the disparity between Black and White (Ward et al., 2004).

Race Medicine: Disparities in cancer Risk and Incidence

Cancer is caused by an aberration of genetics. The aberration can be due to an inherent genetic mutation that can be passed on through generations. It can also be due to environmental influences on a gene or series of genes. Some cohorts have a higher prevalence of a specific genetic mutation or a series of genes that increase risk. Some cohorts have increased or decreased risk due to environmental exposures. An understanding of both cancer genetics and population genetics is critical for those who wish to approach disparities in health in a rational scientific way, in which pertinent questions are identified and clearly stated.

Over the years, American medicine has placed much interest on genetic differences among the races. The concept that phenotypic differences translate into biologic differences was the basis of "Race Medicine." This concept was commonly accepted in the America of the 19th and early 20th centuries. It was one of the reasons that the study commonly known as the "The Tuskegee Syphilis Study," which began in 1932, was thought reasonable and ethical. Syphilis was thought to be a very different disease in Blacks versus Whites. Many actually believed that syphilis rarely killed infected Blacks, but frequently killed infected Whites (Brawley, 1998). Race Medicine is still with us today. This belief in biologic differences among the races has crept into the discipline of health disparities (Goldson, Henschke, Leffall, & Schneider, 1981). It is unfortunate we do sometimes read that "breast cancer is a different disease in Blacks versus Whites" or that "prostate cancer is a different disease in Blacks versus Whites."No race has a monopoly on the good cancers or on the bad cancers. It is also true that a higher proportion of Black American women with breast cancer have the more aggressive types (Brawley, 2010; Lund et al., 2009).

A good scientific question is, "Why do a higher proportion of Black women with breast cancer have the poorer-prognosis disease compared to White women?" A second good question rarely discussed is, "Why do a higher proportion of White women have the good-prognosis breast cancers?" It is known that there are racial differences in a number of environmental factors that are correlated with breast cancer risk. Indeed, in the United States there are racial differences in the proportion beginning menstruation at an early age, birthing patterns, the proportion that is obese, and the use of postmenopausal hormones (Lund et al., 2008). Could race be a surrogate for SES status? Some data suggests that SES and social deprivation not only correlate with the risk of cancer, but also with pathologic factors (Gordon, 1995; Gordon, 2003). Several studies suggest that poor White women with breast cancer are more likely to be diagnosed with estrogen receptor negative tumors (Gordon, 1995; Thomson, Hole, Twelves, Brewster, & Black, 2001). It is unknown how poverty influences pathology of disease. It may be through lifelong diet, and birthing habits. Diets high in calories during childhood can affect age at menarche. Earlier age at menarche is known to be associated with increased breast cancer risk later in life. A higher proportion of the poor are overweight or obese. Increased body mass index has been correlated with increased risk of postmenopausal breast cancer. Similarly, increased body mass index, which is more common in African American males compared to White males, has been correlated with increased risk for more aggressive prostate cancer (Amling et al., 2004; Spangler et al., 2007).

While it is important to study race, it is also important not to overemphasize race. Even when a specific genetic difference is highly associated with a race or ethnicity, it might more appropriately be considered familial rather than racial or ethnic. A specific gene or series of genes can be conserved among families, and a closed society will conserve genetic traits within that society. Segregation on the basis of race, ethnicity, economics, or other factors can lead to increased prevalence of a specific gene or series of genes in the segregated population. This has been demonstrated in several diseases with a well-defined genetic basis, such as Tay Sachs disease, cystic fibrosis, and sickle cell disease. Each of these diseases has a higher prevalence in, but is not exclusive to, a specific racial/ethnic group. Even the mutation of BRCA common among Ashkenazi Jews has been linked to a small number of individuals having it about 1,000 years ago, and it is now preserved through ethnic segregation. As populations in Europe and America mix, these genetic differences will lessen (Offit et al., 1996).

There are genetic variations between human populations. A gene, or even a single nucleotide polymorphism (SNP) allele, that is common in one geographic, racial, or ethnic group may be rare in another. Some of these genetically based differences translate into a difference in disease risk among populations. Some of these differences have been associated with an environmental influence and can offer a survival advantage. Sickle cell disease, for example, is associated with area of geographic origin. People from Spain, Italy, Greece, and the Middle East, as well as northern and sub-Saharan Africa, have sickle cell trait and sickle cell anemia. While the prevalence of sickle cell trait and sickle cell anemia is higher in sub-Saharan Africa, there is also a prevalence in people originating from southern Europe and considered to be of White race. Sickle cell is not found among Black Africans originating from southern Africa. This genetic mutation is thought to be an example of genetic selection. Those who had sickle cell trait had some advantage during a massive malaria epidemic several thousand years ago. That advantage extends to those with sickle cell trait to this day (Brawley et al., 2008). Sickle cell disease is an excellent example of environmental influences on genetics. The fact that it parallels a geographic area where people are considered of White race and Black race is also a good lesson, as most Americans think of sickle cell disease solely as an affliction of Blacks.

There are other genetic markers that correspond with areas of geographic origin far better than with skin color or race (Fijumara & Rajagoplan, 2011). Glucose 6 phosphate dehydrogenase deficiency is common in, but not monopolized by, people originating in the Middle East and Mediterranean regions (Beutler, Lisker, & Kuhl, 1990). Alcohol dehydrogenase deficiency is common in persons from certain areas of Asia. There are differences in metabolism of some drugs by genetic markers that tend to parallel area of geographic origin. The drug irinotecan, or CPT 11, is used in the treatment of colon cancer. It is metabolized by the UDP-glucuronosyltransferase 1-1 gene (UGT1A1) gene in the liver. Certain polymorphisms of the gene metabolize the drug slower than others. The U.S. Food and Drug Administration recommends that patients with certain polymorphisms of UGT1A1 receive reduced doses of the drug. It is one of the first cancer drugs dosed according to genotype. Asian populations tend to have a slower UGT1A1 compared to populations originating in Europe (Beutler, Gelbart, & Demina, 1998). The word "tend" is important. It is best to do the laboratory tests necessary to assess UGT1A1 in the specific patient than to do racial medical profiling and assume that all Asians should be dose reduced. Racial medical profiling can deprive a patient of a therapeutic dose of this drug. The movement toward personalized medicine, with its emphasis on the genetics of the individual, may be one way that we stop racial medical profiling.


Much cancer research shows that equal treatment yields equal outcomes, among equal patients (Bach, Cramer, Warren, & Begg, 1999). Race in and of itself need not be a factor in the outcomes of cancer treatment. There are Black-White disparities in both the availability and use of care and in the quality of care received. In the field of oncology, these studies overwhelmingly show that the proportion of Blacks getting adequate screening, diagnostics, and treatment is less than the proportion of Whites. Some studies show that Blacks in the southern United States are more likely to get less than optimal cancer care compared to Blacks in the northeast, who are less likely to get optimal care compared to Blacks in the west (Harlan, Brawley, Pommerenke, Wali, & Kramer, 1995).

As suggested earlier, while race is a correlative factor in these disparities, the driver of the disparities may be due to socioeconomic differences, and not racial. Studies suggest that some disparities in treatment are due to racism and some are due to SES discrimination. Other important factors are lack of access to good therapy or lack of convenient access to needed therapy. Comorbid diseases (including obesity) can also make aggressive cancer therapy inappropriate. Some disparities in cancer treatment may be due to comorbid diseases and may be appropriate (Griggs et al., 2007). Unfortunately, very few studies have looked at disparities by socioeconomic status, and even fewer have looked at practice pattern disparities in other racial/ethnic groups such as Hispanics, Asians, or Native Americans. Little effort has been put into assessing outcomes in other disenfranchised communities, such as refugee communities, or the lesbian, gay, bisexual, and transgender communities (Mayer et al., 2008).

Cultural differences in acceptance of therapy and lack of education about the disease are huge drivers in the disparate receipt of health care. Some cultures have fatalistic views toward cancer and a cancer diagnosis. This causes them to run away from good care when it is available. Culturally sensitive interventions to educate and create understanding about disease can help bring about health equity. Experience tells us that a successful intervention is created by someone who understands and cares about the population with the disparity. All interventions should be carefully and rigorously assessed for effectiveness before full implementation. These interventions must be implemented with sensitivity and by a trusted source. At the same time, a highly degreed health care expert may be unsuccessful. The concept of community-based participatory research is based on this finding (Ford et al., 2009).


Health equity can only be achieved through open-mindedness and a committed interest on the part of health care providers, social scientists, health consumers, and health advocates. In some instances, the medical and medical-social professions have to change their preconceived notions. In order to achieve health equity, it is imperative that we:

•    Realize the meaning of race, ethnicity, area of geographic origin, and socioeconomic status, and appreciate the limitations of those categories.

•    Understand the role of cancer genetics, population genetics, and the role of environmental interactions with genes.

•    Value the scientific method as we rigorously assess culturally sensitive interventions to reduce health disparities and bring about health equity.

•    Care about the fact that there are disparities, and care about and respect the uniqueness of the patients we serve.

Each of the researchers whose works are presented in this topic has taken steps along this journey. If we all follow these principles, think of the major impact we can have on the lives of future generations.

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