- Certain genetic variations exist only in African-Americans.
- Some of these variations led to higher colorectal cancer risk.
- One variant was linked to decreased risk for cancer of the left side of the colon.
“Vitamin D deficiency is associated with a higher risk for colorectal cancer,” said Fabio Pibiri, Ph.D., a postdoctoral associate at the University of Illinois at Chicago. “Because increased skin pigment lowers the amount of ultraviolet light that can be used to make vitamin D in the skin, more African-Americans than whites are vitamin D-deficient, putting them at higher risk for colorectal cancer. Our research showed that genetic differences may play an important role as well.”
Pibiri and colleagues evaluated 39 single nucleotide polymorphisms (SNPs), DNA sequence variations, in vitamin D-related genes in 1,799 African-Americans — 961 patients with colorectal cancer and 838 controls — who participated in the North Carolina Colorectal Cancer Study and the Chicago Colorectal Cancer Consortium.
They found several SNPs in genes involved in the generation and destruction of vitamin D that were associated with colorectal cancer.
One variation in the gene that tells a cell to make the protein that destroys vitamin D was linked to protection from developing colorectal cancer on the left side of the body. According to Pibiri, this variation is specific to African-Americans and the finding may explain why African-Americans have a lower proportion of left-sided colorectal cancer compared with right-sided colorectal cancer.
“It seems likely that these differences in the DNA sequence alter the function of the vitamin D-related genes,” said Pibiri. “For example, we hypothesize that the genetic variation linked to protection decreases levels of the vitamin D-destroying protein. Now all we need to do is show that.”
The National Institutes of Health, the American Institute for Cancer Research and the American Cancer Society Illinois Division provided funding for this research.
About the American Association for Cancer Research
Founded in 1907, the American Association for Cancer Research (AACR) is the world’s first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 34,000 laboratory, translational and clinical researchers; population scientists; other health care professionals; and cancer advocates residing in more than 90 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis and treatment of cancer by annually convening more than 20 conferences and educational workshops, the largest of which is the AACR Annual Meeting with more than 17,000 attendees. In addition, the AACR publishes seven peer-reviewed scientific journals and a magazine for cancer survivors, patients and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the scientific partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration and scientific oversight of team science and individual grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and policymakers about the value of cancer research and related biomedical science in saving lives from cancer.
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