We are five years into what has been termed the genome era (2). In this relatively short period of time knowledge of the human genome has expanded dramatically, overturning widely held notions about genomic structure and function. The view of the genome as a static collection of genes has changed to a dynamic network model where overlapping regulatory elements, coding, and non-coding sequences are transcribed and interact in ways that have yet to be defined (3). The implementation of haplotype maps and the development of ultra high-throughput genotyping have shifted the search for gene variants associated with disease away from small case-control studies towards genome-wide association studies that can assess up to 500,000 single nucleotide polymorhpisms (SNPs), common, yet minute changes that occur in human DNA, in tens of thousands of individuals (4). As a result, the number of allelic variants associated with common disease, including cancer, has been climbing, with a burst of discoveries occurring in the past year. Notably new gene-disease associations have been identified in breast cancer (5–7), colon cancer (8–10), and prostate cancer (11–14). Often, these variants occur at different frequencies in different populations. Defining such variation, as well as differences in larger structural elements (15) and gene expression (16,17), in human populations and their implications for health has become an important focus of current genomic research. Given its significant association with health and disease, Science Magazine identified human genetic variation as the breakthrough of 2007(18).

Studies of human genetic variation are certainly not without their controversies, many of which result from publicity of unwarranted and unfounded conclusions about innate differences between human groups. 2007 was also a year of such controversy, precipitated by Nobel laureate Dr. James Watson’s comments regarding race, genetics and intelligence. Watson stated in an interview for his book published in 2007 (19) that he is, “… ‘inherently gloomy about the prospect of Africa’ because ‘all our social policies are based on the fact that their intelligence is the same as ours—whereas all the testing says not really”(20). His comments were widely denounced by the scientific community (21, 22).

Thus, the year of human genetic variation was not entirely about celebrating our growing understanding of the association between genetic individuality and disease but also about our need to study the social and clinical implications of such findings. It was a year where discussion of genetics and human difference at times created an uncomfortable undertone of racism. 2007 emphasized the need for addressing ethical issues surrounding genetic technologies, genetic information, race, and health inequities, all of which are essential to improve the public’s health.

There is an ongoing debate surrounding conceptualizations of race. Common understandings of race conflate biology and culture and place social meaning on physical characteristics (23). Racial categories can reflect culture, history, socioeconomic, and political status, as well as ancestral geographic origin (24). That is to say, time and place, as well as legal, political and religious realities, can impact racial identity. There are multiple dimensions of racial identity: internal (self-identified), external (what others attribute to an individual), and the public presentation of an individual’s sense of their racial identity. These components are fluid and context specific. Social scientists describe racial formation as a “process by which social, economic and political forces determine the content and importance of racial categories” (25). Though popular notions of race often create categories based on group similarities that are phenotypic in nature, the factors influencing racial identity are revealed to be more complex with critical examination.

Despite the fluid and socially constructed nature of racial groupings, there have been attempts to classify individuals into discrete categories throughout history. The word “race” and many of the ideas about physical and mental human difference associated with it emerged during the “age of exploration” when increasing interaction with people from different parts of the world led Europeans to begin to sort individuals into groups (26). For centuries, science has searched to group people. In 1758 Carolus Linnaeus’ Systema naturae classified the human population into a four-race system. This model was based on geography and physical features, but also incorporated negative stereotypes (27). Linnaeus’s student J.F. Bluemenbach shifted racial taxonomy from a four race system that reflected geography to a linear, five race system that ranked groups based on their putative worth (28). From this point forward studies of biological difference between the “races” were frequently coupled with pejorative and racist terms. The eugenics movement of the late 19^th and early 20^th centuries (29) perpetuated such division, articulating them as rooted in genetics.

Today the United States Census Bureau collects race and ethnicity information using standards set forth by the United States Office of Management and Budget (OMB). These standards are socially and politically constructed and have changed over time as conceptions of race and ethnicity have shifted (Table 1). Currently, the OMB standards include five minimum categories for race (American Indian or Alaska Native, Asian, Black or African American, Native Hawaiian or Other Pacific Islander, and White) and two categories for ethnicity (Hispanic or Latino and Not Hispanic or Latino) (30). The existing guidelines, which give individuals the ability to identify with more than one racial category, arose in response to criticism that the previous system did not accurately represent the United States population, specifically the increasing proportion who identify as multiracial (31). OMB included the caveat: “The racial and ethnic categories set forth in the standards should not be interpreted as being primarily biological or genetic in reference. Race and ethnicity may be thought of in terms of social and cultural characteristics as well as ancestry” (30).

In addition to differences in inherited mutations, differences in cancer causing somatic mutations that vary with race and ethnicity can also play a role in identifying the most effective treatments for an individual patient. The anti-cancer drug gefitinib (Iressa; AstraZeneca, London, UK) has shown evidence of increasing survival for Asian-origin patients with non-small-cell lung cancer who were refractory to or intolerant of their latest chemotherapy regimen (34). Researchers have proposed that the mechanism behind increased drug responsiveness of this population is related to somatic mutations in the epidermal growth factor receptor that occur more frequently in East Asians, women, non-smokers, and patients with adenocarcinoma (35). In another example, a high prevalence of basal-like tumors associated with decreased survival have been found in young African American women with breast cancer (36). Drug regimens tailored to target basal-like tumors could be a successful treatment option for African American women with this type of breast cancer. In prostate cancer, differences in the expression profiles of immune-response genes between tumors in African American and European American men have recently been identified, which could have implications for utilization of immunotherapy treatment (37). Still, relying on the proxies of race and ethnicity to guide clinical decisions will not be as accurate as directly assessing the genomic and environmental factors that predict treatment response and efficacy. This is the promise of personalized medicine (38).

Race and ethnicity are also used in addition to family history as indicators for genetic testing for known cancer susceptibility variants. The most widely known example of this is BRCA 1/2 testing for breast and ovarian cancer risk. It is documented that mutations are found at higher rates in individuals with a family history of early onset breast or ovarian cancer, particularly individuals with Ashkenazi Jewish ancestry (39). Still, a recent study of the prevalence of BRCA1 mutations in an ethnically diverse sample of breast cancer patients showed that they occurred more frequently than expected in both Hispanic and young African American women (40) highlighting the need for the consideration of the utilization of genetic testing in a more diverse population(41).

In addition to testing for genetic susceptibility, cancer screening is another area where race and ethnicity are used to target racial and ethnic groups that may benefit from screening leading to early diagnosis. For example, mortality for colorectal cancer in African American men are 2 to 3 times higher than the general population; therefore, this group may benefit from earlier and more frequent screening for this disease (42). Prostate cancer screening has been identified as one area for earlier screening of African American men. Jones and colleagues have identified nurses as having an important role in educating African American men about existing disparities related to prostate cancer (43).

Rates of cancer incidence, morbidity, and mortality differ among population groups, including groups defined using the OMB categories. Some of these differences may be explained by genetic factors, but variation in health outcomes between racial and ethnic groups may also be attributed to social determinants in health including differences in treatment. Human beings, including health professionals, make sense of the world using universal cognitive strategies that categorize people into groups. Acquired beliefs about these groups are unconsciously applied to individuals who are assigned to them. It has been shown that practitioners unconsciously make assumptions that their racial and ethnic minority patients will not understand the diagnosis or will reject certain treatment options and communicate these topics differently to them, which may lead to disparities in patient outcomes (45–46).

Healthcare providers may also unknowingly interpret symptoms differently based on the race and ethnicity of the patient, arriving at different clinical decisions and making different treatment recommendations (47, 48). The influence of unconscious stereotyping on how health professionals act in clinical encounters can impact patient satisfaction and behaviors (44, 49). Thus, the effectiveness of the patient-provider relationship for eliciting positive health outcomes is influenced by both the conscious and unconscious cognitive processes of both participants.

In addition to implicit processes, the patient’s and provider’s explicit biases and preferences can also influence health outcomes. In this way conscious stereotyping in healthcare interactions and historical distrust of the medical profession are two barriers to effective health outcomes for minority patients. Lillie-Blanton and colleagues (50) reported that differences in access and utilization of health services may also play a role in health inequities between groups. African American and Latino patients are more likely to have a hospital-based rather than an office-based healthcare provider than white patients, independent of socio-demographic factors, health status, and insurance status. This difference in provider location could be a result of geographic or socio-cultural barriers, patient preferences or both (50), but can have implications for cost, content and quality of care, which can in turn impact patient satisfaction and outcomes (51).

Getting at the root causes of racial and ethnic health disparities and identifying interventions to counteract them will include untangling the effects of implicit and explicit bias in patient provider interactions and access to, and utilization of, healthcare service. This complexity of this process is illustrated in the field of cancer, as disparities have been documented in both risk communication and treatment (51). Blackman and Masi point to several studies that show variation in follow-up care after cancer-related screenings when comparing racial and ethnic groups (52). Notably, minority women frequently receive their mammogram results later than white women (52). Also, white women are more likely than black women to be asked about family history of breast cancer (53). Disparities in the management of cancer related pain between racial and ethnic groups (54, 55) as well as in utilization of surgery and radiation (56–58) have also been found.