Understanding the Association of Type 2 Diabetes Mellitus in Breast Cancer Among African American and European American Populations in South Carolina

Abstract

IntroductionAfrican-American (AA) women in the U.S. experience the lowest breast cancer survival rates among all ethnic groups compared to European Americans. 1,2 Breast cancer (BrCA) is the second leading cause of cancer death in South Carolina regardless of race. 3 Additionally, South Carolina has an overall BrCA mortality rate that is greater than the national average, driven exclusively by the high BrCA mortality rates seen in AAs. 4 The state ranks 7 th in diabetes prevalence in the United States, affecting approximately 375,000 people. 5 Because diabetes may promote the proliferation of cancer cells and metastasis 6 the increasing prevalence of diabetes raises important questions about the possible relationship between diabetes and BrCA.Recent meta-analytic studies suggest that type 2 diabetes (T2DM) can have incongruous effects depending on the anatomic site of cancer; e.g., diabetes may show a protective effect in prostate cancer and a detrimental effect in BrCA. 6 The population of SC is an ideal environment to examine the ethnic differences in T2DM and BrCA due to the large percentage of AAs (28%) residing in SC 7 and the excellent quality of available cancer incidence and mortality data. 1,4 Also, T2DM prevalence has increased 51% over the past 10 years in SC and now affects 1 in 8 AAs. 5Address of correspondence to : Marsha Samson, Cancer Prevention and Control Program, 915 Greene Street, Columbia, SC, 29208 [ msamson@email.sc.edu], 786.877.7287. Conflict of interest: None of the authors have conflicts of interest to discloseCompliance with Ethical Standards" on the title page when submitting a paper: Ethical approval: This article does not contain any studies with human participants or animals performed by any of the authors. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptFor this analysis, we sought to link information from the South Carolina Central Cancer Registry (SCCCR) 4 and Medicaid records, as we previously had done with colorectal cancer, 8 to examine the association between incident T2DM and BrCA stage at diagnosis and mortality due to the disease. The rising disparities between EAs and minorities in BrCA patterns of incidence and mortality has been well-documented in the US. 1,9 These racial disparities are evident in age at diagnosis, disease virulence, and prognosis; and, ultimately, survival and death. Reasons for the differences are unclear; however, they may be attributed to actual biological differences by race in the nature of the disease; comorbidities; and variable access to, and willingness to use, health care services. In this study, we examine the association of T2DM and BrCA stage and survival rates in both AA and EA women. In addition to understanding the relationship between T2DM and BrCA, we also will compare the association by race to consider potential differences that might be necessary to include in future implementations of race-specific health interventions related to diabetes and BrCA. MethodsFor the use of de-identified da...

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