Abstract B84: Lower vitamin D status among black Americans may explain much of the racial disparities in cancer outcomes

The purpose of this study is to examine published data on disparities in cancer survival rates to see whether disparities in serum 25-hydroxyvitamin D [25(OH)D] levels could explain a significant portion of the findings. African-Americans generally have higher cancer incidence rates and lower cancer survival rates than White-Americans. Many studies have found that after adjusting for cancer stage at time of diagnosis and quality of treatment, race is the only factor that accounts for the disparity. Numerous ecological and a reasonable number of observational studies have found solar ultraviolet-B doses, vitamin D intake, and/or prediagnostic serum 25-hydroxyvitamin D [25(OH)D] levels inversely correlated with incidence and/or mortality rates for about 20 types of cancer (1). African-Americans have lower population mean serum 25(OH)D levels in the United States: 16 ng/mL vs. 26 ng/mL (2). Based on observational studies of prediagnostic serum 25(OH)D and incidence rates for breast and colorectal cancer (3) and cardiovascular disease (4,5), as well as all-cause mortality rates (4), this difference seems to account for the approximately 25% increased all-cause mortality rate for African-Americans compared to white Americans (6). The journal literature will be searched for papers published in the United States reporting disparities in cancer survival after accounting for other factors. Attention will be given to examining differences for the well-known vitamin D-sensitive cancers and other types of cancer. One recent paper reported that the well-documented vitamin D-sensitive cancers: bladder, breast, colorectal, esophageal, uterine, and, likely, head and neck, have the highest difference in black-white survival rates, while those cancers with uncertain relation to vitamin D: liver, lung, pancreatic, and prostate cancer, have much lower differences (7). Thus, disparities in serum 25(OH)D levels likely explain much of the disparities in cancer outcomes attributed to African-American race. Increasing serum 25(OH)D levels for all but especially African-Americans to above 40 ng/mL appears to be the most efficient way to reduce cancer incidence and mortality rates in general and disparities in particular.

References:

1. Grant WB, Mohr SB. Ecological studies of ultraviolet B, vitamin D and cancer since 2000. Ann Epidemiol. 2009;19:446-54.

2. Ginde AA, Liu MC, Camargo CA Jr. Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Arch Intern Med. 2009;169:626-32

3. Gandini S, Boniol M, Haukka J, et al. Meta-analysis of observational studies of serum 25-hydroxyvitamin D levels and colorectal, breast and prostate cancer and colorectal adenoma. Int J Cancer. 2010 May 6. [Epub ahead of print]

4. Ginde AA, Scragg R, Schwartz RS, Camargo CA Jr. Prospective study of serum 25-hydroxyvitamin D level, cardiovascular disease mortality, and all-cause mortality in older U.S. adults. J Am Geriatr Soc. 2009;57: 1595-603.

5. Parker J, Hashmi O, Dutton D, et al. Levels of vitamin D and cardiometabolic disorders: systematic review and meta-analysis. Maturitas. 2010;65:225-36.

6. Bibuld D. Health disparities and vitamin D. Clinic Rev Bone Mner Metab. 2009;7:63-76.

7. Morris AM, Rhoads KF, Stain SC, Birkmeyer JD. Understanding racial disparities in cancer treatment and outcomes. J Am Coll Surg. 2010;211:105-13.

Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):B84.