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Since the signing of the National Cancer Act in 1971 cancer research has produced many concrete gains in cancer prevention, diagnosis and treatment. The four most common cancers in the United States (breast, prostate, lung and colon) have all seen marked improvements in early detection and treatment that have led to gradual and persistent decreases in cancer deaths since 1975.¹ However, the fruits of cancer research have not always been equally distributed throughout the US population. Racial/ethnic minorities and the poor, who have historically been medically underserved, continue to suffer disproportionately from cancer.

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.”² These populations may be defined by level of education, race/ethnicity, gender, geographic location, or income and disparities have been well documented in each of these disadvantaged groups. For example, African American patients with breast cancer are more likely to experience delays in initiation of surgery or chemotherapy, are less likely to receive modern surgical techniques, and are less likely to receive recommended radiation or chemotherapy after surgery.^3-7 These and other described disparities in care likely contribute to the fact that while African Americans are actually less likely to be diagnosed with breast cancer, they are more likely to die from their cancer.⁸ The underserved suffer disproportionately from cancer and its associated effects, including premature death and these groups have a higher incidence and mortality for many types of cancer.⁹

Some specific examples of disparate cancer incidence, treatment and outcomes^10-11

• 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 15 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 40 percent higher.
• Native Americans have the lowest 5 year cancer survival rate of any group in the United States.
• 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.
• For all cancers combined Hispanics have 20% lower incidence rates and 30% lower death rates compared with whites; however liver cancer rates are twice as high for Hispanics
• Americans in poor counties (lowest quintile of income) have a 29% higher mortality rate for men and a 15% higher mortality rate for women than those in the wealthiest counties (highest quintile of income). This increase in mortality, associated with poverty, is also seen when controlling 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, there are well documented disparities in screening, stage at diagnosis and treatment for African American men who ultimately have worse overall survival.^11-13 However, even when adjusting for differences in stage and treatment the disparity in survival persists, suggesting that biological factors might account for some of the observed survival disparity.¹⁴ Several genetic aberrations have been identified that are associated with the risk of developing prostate cancer, and developing more aggressive cancer. African Americans are more likely to harbor these genetic aberrations, and some studies estimate this could impart a 5-fold increase in risk of developing prostate cancer.^15-20 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/ethnic minority groups that have been historically underrepresented in cancer research, ranging from 3 -20 percent of eligible participants. 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.^21-23

Addressing Cancer Health Disparities

Although many programs nationally and locally are addressing the issue of health care disparities, more must be done. The Johns Hopkins Sidney Kimmel Comprehensive Cancer Center has teamed up with the Indiana University Simon Cancer Center and The Ohio State James Comprehensive Cancer Center to offer a 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 and understanding the needs of under-privileged, indigent or disadvantaged people. It is a 9-week program in which medical students will have the opportunity to conduct laboratory research. In addition, students are assigned clinical mentors in each of the three core oncology fields (surgical oncology, medical oncology and radiation oncology). An 8-week series of didactic lectures and journal clubs will cover the genetic and biological basis of cancer, cancers by site, conventional and emerging strategies for cancer therapy, end-of-life care, health care disparities, and strategies for effective outreach. Students are provided with a stipend and free housing. Our hope is that this program will produce compassionate and informed physicians who will proudly join in the crusade against cancer.

References

1. Surveillance, Epidemiology, and End Results (SEER) Program (www.seer.cancer.gov) SEER*Stat Database: Incidence - SEER 9 Regs Research Data, Nov 2016 Sub (1973-2014) <Katrina/Rita Population Adjustment> - Linked To County Attributes - Total U.S., 1969-2015 Counties, National Cancer Institute, DCCPS, Surveillance Research Program, released April 2017, based on the November 2016 submission.
2. Institute NC. Cancer Health Disparities. 2008; https://www.cancer.gov/about-nci/organization/crchd/cancer-health-disparities-fact-sheet. Accessed 10/16/17, 2017.
3. Bleicher RJ, Ruth K, Sigurdson ER, et al. Preoperative delays in the US Medicare population with breast cancer. Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2012;30(36):4485-4492.
4. Dreyer MS, Nattinger AB, McGinley EL, Pezzin LE. Socioeconomic status and breast cancer treatment. Breast cancer research and treatment. 2017.
5. Fedewa SA, Ward EM, Stewart AK, Edge SB. Delays in adjuvant chemotherapy treatment among patients with breast cancer are more likely in African American and Hispanic populations: a national cohort study 2004-2006. Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2010;28(27):4135-4141.
6. Reeder-Hayes KE, Bainbridge J, Meyer AM, et al. Race and age disparities in receipt of sentinel lymph node biopsy for early-stage breast cancer. Breast cancer research and treatment. 2011;128(3):863-871.
7. Smith EC, Ziogas A, Anton-Culver H. Delay in surgical treatment and survival after breast cancer diagnosis in young women by race/ethnicity. JAMA surgery. 2013;148(6):516-523.
8. Feinglass J, Rydzewski N, Yang A. The socioeconomic gradient in all-cause mortality for women with breast cancer: findings from the 1998 to 2006 National Cancer Data Base with follow-up through 2011. Annals of epidemiology. 2015;25(8):549-555.
9. DeSantis CE, Siegel RL, Sauer AG, et al. Cancer statistics for African Americans, 2016: Progress and opportunities in reducing racial disparities. CA: a cancer journal for clinicians. 2016;66(4):290-308.
10. Singh GK, Jemal A. Socioeconomic and Racial/Ethnic Disparities in Cancer Mortality, Incidence, and Survival in the United States, 1950-2014: Over Six Decades of Changing Patterns and Widening Inequalities. Journal of environmental and public health. 2017;2017:2819372.
11. Jemal A, Ward EM, Johnson CJ, et al. Annual Report to the Nation on the Status of Cancer, 1975-2014, Featuring Survival. Journal of the National Cancer Institute. 2017;109(9).
    
12. Sauer AG, Siegel RL, Jemal A, Fedewa SA. Updated Review of Prevalence of Major Risk Factors and Use of Screening Tests for Cancer in the United States. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2017;26(8):1192-1208.
    
13. Holmes JA, Bensen JT, Mohler JL, Song L, Mishel MH, Chen RC. Quality of care received and patient-reported regret in prostate cancer: Analysis of a population-based prospective cohort. Cancer. 2017;123(1):138-143.
    
14. Evans S, Metcalfe C, Ibrahim F, Persad R, Ben-Shlomo Y. Investigating Black-White differences in prostate cancer prognosis: A systematic review and meta-analysis. International journal of cancer. 2008;123(2):430-435.
    
15. Freedman ML, Haiman CA, Patterson N, et al. Admixture mapping identifies 8q24 as a prostate cancer risk locus in African-American men. Proceedings of the National Academy of Sciences of the United States of America. 2006;103(38):14068-14073.
    
16. Haiman CA, Patterson N, Freedman ML, et al. Multiple regions within 8q24 independently affect risk for prostate cancer. Nature genetics. 2007;39(5):638-644.
    
17. Powell IJ, Bollig-Fischer A. Minireview: the molecular and genomic basis for prostate cancer health disparities. Molecular endocrinology (Baltimore, Md). 2013;27(6):879-891.
    
18. Wang BD, Ceniccola K, Hwang S, et al. Alternative splicing promotes tumour aggressiveness and drug resistance in African American prostate cancer. Nature communications. 2017;8:15921.
    
19. Wang BD, Ceniccola K, Yang Q, et al. Identification and Functional Validation of Reciprocal microRNA-mRNA Pairings in African American Prostate Cancer Disparities. Clinical cancer research : an official journal of the American Association for Cancer Research. 2015;21(21):4970-4984.
    
20. Wang BD, Yang Q, Ceniccola K, et al. Androgen receptor-target genes in african american prostate cancer disparities. Prostate cancer. 2013;2013:763569.
    
21. Giuliano AR, Mokuau N, Hughes C, et al. Participation of minorities in cancer research: the influence of structural, cultural, and linguistic factors. Annals of epidemiology. 2000;10(8 Suppl):S22-34.
    
22. Freeman HP, Chu KC. Determinants of cancer disparities: barriers to cancer screening, diagnosis, and treatment. Surgical oncology clinics of North America. 2005;14(4):655-669, v.
    
23. Svensson K, Ramirez OF, Peres F, Barnett M, Claudio L. Socioeconomic determinants associated with willingness to participate in medical research among a diverse population. Contemporary clinical trials. 2012;33(6):1197-1205.