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Hofmann, Jonathan N.; Corley, Douglas A.; Colt, Joanne S.; Shuch, Brian; Chow, Wong-Ho; Purdue, Mark P.

doi: 10.1097/EDE.0000000000000305
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Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, hofmannjn@mail.nih.gov

Division of Research, Kaiser Permanente Northern California, Oakland, CA

Division of Cancer, Epidemiology and Genetics, National Cancer Institute, Bethesda, MD

Department of Urology, Yale School of Medicine, New Haven, CT

Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX

Division of Cancer, Epidemiology and Genetics, National Cancer Institute, Bethesda, MD

Ontario Institute for Cancer Research, Toronto, ON, Canada

Supported by Intramural Research Program of the National Institutes of Health.

We thank Dr. Grant for his comments regarding our recent article on the role of hypertension and chronic kidney disease in the racial disparities in the incidence of renal cell carcinoma among members of Kaiser Permanente Northern California, a large integrated health care system in the greater San Francisco Bay area.1 Dr. Grant presents intriguing evidence to suggest that racial differences in circulating 25-hydroxyvitamin D [25(OH)D] levels may contribute to the disparities in renal cell carcinoma, and this hypothesis warrants further examination. However, we note that the findings of studies evaluating the relation between circulating 25(OH)D levels and renal cell carcinoma risk have been inconsistent. In contrast to the more recent report from the EPIC cohort,2 no association was observed in a prospective investigation of renal cell carcinoma in the NCI Cohort Consortium that included a larger number of cases (560 and 775 cases, respectively).3 Future studies evaluating the association between circulating 25(OH)D levels and risk of renal cell carcinoma among blacks and other non-white populations would be informative.

Beyond circulating 25(OH)D levels, several other factors might also explain how hypertension and chronic kidney disease contribute to racial disparities in the overall burden of renal cell carcinoma including differences by race in hypertension control and management of chronic kidney disease, the prevalence of modifiable risk factors related to renal cell carcinoma (e.g., obesity, smoking), and/or genetic susceptibility. Further investigation of each of these factors will likely yield important insights into the underlying mechanisms through which hypertension and chronic kidney disease influence renal cell carcinoma risk and will help us to better understand the racial disparities in this malignancy.

Jonathan N. Hofmann

Occupational and Environmental Epidemiology Branch

Division of Cancer Epidemiology and Genetics

National Cancer Institute

Bethesda, MD

hofmannjn@mail.nih.gov

Douglas A. Corley

Division of Research

Kaiser Permanente Northern California

Oakland, CA

Joanne S. Colt

Division of Cancer

Epidemiology and Genetics

National Cancer Institute

Bethesda, MD

Brian Shuch

Department of Urology

Yale School of Medicine

New Haven, CT

Wong-Ho Chow

Department of Epidemiology

The University of Texas MD Anderson Cancer Center

Houston, TX

Mark P. Purdue

Division of Cancer

Epidemiology and Genetics

National Cancer Institute

Bethesda, MD

Ontario Institute for Cancer Research

Toronto, ON

Canada

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REFERENCES

1. Hofmann JN, Corley DA, Zhao WK, et al. Chronic kidney disease and risk of renal cell carcinoma: differences by race. Epidemiology. 2015;26:59–67
2. Muller DC, Fanidi A, Midttun Ø, et al. Circulating 25-hydroxyvitamin D3 in relation to renal cell carcinoma incidence and survival in the EPIC cohort. Am J Epidemiol. 2014;180:810–820
3. Gallicchio L, Moore LE, Stevens VL, et al. Circulating 25-hydroxyvitamin D and risk of kidney cancer: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am J Epidemiol. 2010;172:47–57
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