Persistent Disparities in Cancer Incidence and Mortality

The war against cancer, initiated in 1971 with the signing of the National Cancer Act by President Nixon, has resulted in many concrete improvements in cancer prevention, diagnosis and treatment. However, the fruits of cancer research have not been equally distributed throughout the US population. Racial/ethnic minorities and the poor, who historically have been medically underserved, continue to suffer disproportionately from cancer(1).

The National Cancer Institute (NCI) defines cancer health disparities as "adverse differences in cancer incidence (new cases), cancer prevalence (all existing cases), cancer death (mortality), cancer survivorship, and burden of cancer or related health conditions that exist among specific population groups in the United States." These groups may be defined by level of education, race/ethnicity, gender, geographic location, or income. Disparities are clearly evident in data collected by the Surveillance, Epidemiology, and End Results (SEER) program, the NCI's authoritative resource for information about cancer incidence and survival. A close look at these cancer incidence and death statistics reveals that the underserved suffer disproportionately from cancer and its associated effects, including premature death. African Americans/Blacks, Asian Americans, Hispanic/Latinos, American Indians, Alaska Natives, and underserved Whites are more likely than the general population to have higher incidence and death statistics for many types of cancer(1).

Some specific examples of disparate incidence and outcomes from the SEER database:

  • Although cancer deaths have declined for both Whites and African Americans/Blacks living in the United States, African Americans/Blacks continue to suffer the greatest burden for each of the most common types of cancer. For all cancers combined, the mortality rate is 25 percent higher for African Americans/Blacks than for Whites.
  • African American/Black women have a lower incidence of breast cancer than the population as a whole, but a mortality rate that is 30 percent higher.
  • Native Americans have the lowest 5 year cancer survival rate of any group in the United States.
  • Vietnamese American women have an incidence of cervical cancer 5 times that of White American women.
  • African American/Black men have the highest incidence rate for prostate cancer in the United States and are more than twice as likely as white men to die of the disease. The lowest death rates for prostate cancer are found in male Asian/Pacific Islanders.
  • Americans in poor counties (20% below the poverty line) have a 13% higher mortality rate from cancer than Americans in wealthier counties (<10% below the poverty line). This increase in mortality, associated with poverty, is also seen when one controls for race.

Epidemiologic studies suggest that the underlying basis for cancer health disparities is multifactorial and differs among different subpopulations and among different cancers. In prostate cancer, for example, it is believed that genetic factors might account, at least in part, for the observed differences. Genetic markers have been identified that are statistically associated with the risk of developing cancer. Different combinations of these gene variants have been found in men from different racial/ethnic backgrounds, and each combination is associated with higher or lower risk for prostate cancer. Nearly all of the variants associated with an increased risk of developing prostate cancer were found most often in African American/Black men. Some variant combinations were associated with a five-fold increased risk of prostate cancer in men of this group2, (3). Studies of this type clearly demonstrate the power of laboratory research to identify factors that contribute to cancer health disparities.

Efforts to unravel the causes of persistent health care disparities have been significantly hampered by the low rate at which individuals in underserved populations elect to participate in clinical trials. Cancer clinical trial participation has been very low among the socially disadvantaged and racial/ehnic minority groups that have been historically underrepresented in cancer research, ranging from 3 -20 percent of eligible participants (4), 5. Many factors appear to negatively impact on clinical cancer research participation. These factors including low socioeconomic status, speaking a primary language other than English, differences in communication styles, mistrust of research and the medical system and lack of knowledge about the origin of cancer(5).

Addressing Cancer Health Disparities

Although many programs nationally and locally are addressing the issue of health care disparities, more must be done. Johns Hopkins and the Sidney Kimmel Comprehensive Cancer Center wishing to aid in the elimination of health care disparities in Oncology will provide a summer fellowship entitled Cancer in the Under-Privileged Indigent or Disadvantaged (CUPID). The mission of this program is to promote the discipline of Oncology among medical students interested in, caring for or understanding the needs of, under-privileged, indigent or disadvantaged people. It is a 7 week program in which medical students will have the opportunity to conduct laboratory research in various aspects of oncology. In addition, there will be formal lectures discussing health care disparities, general oncologic principles, and specific diseases prevalent in underserved populations. The SKCCC and Hopkins will provide the students with a generous stipend and housing. Our hope is that this program will produce physicians who will proudly join in the crusade against cancer.

References

  1. Harper, S. & Lynch, J. in Selected Comparisons of Measures of Health Disparities: A Review Using Databases Relevant to Healthy People 2010 Cancer-Related Objectives. (National Cancer Institute, Bethesda, Maryland, 2007).
  2. Freedman, M. L. et al. Admixture mapping identifies 8q24 as a prostate cancer risk locus in African-American men. Proc. Natl. Acad. Sci. U. S. A. 103, 14068-14073 (2006).
  3. Haiman, C. A. et al. Multiple regions within 8q24 independently affect risk for prostate cancer. Nat. Genet. 39, 638-644 (2007).
  4. Freeman, H. P. & Chu, K. C. Determinants of cancer disparities: barriers to cancer screening, diagnosis, and treatment. Surg. Oncol. Clin. N. Am. 14, 655-69, v (2005).
  5. Giuliano, A. R. et al. Participation of minorities in cancer research: the influence of structural, cultural, and linguistic factors. Ann. Epidemiol. 10, S22-34 (2000).
  6. ASCO. Study of the oncology workforce seeks to determine U.S. cancer care needs for the future. Oncology (Williston Park) 20, 1718 (2006).
  7. Schmidt, C. Komen/ASCO program aims to swell ranks of minority oncologists. J. Natl. Cancer Inst. 101, 224-5, 227 (2009).