Vitamin D Clinical Evidence

The Journal of Environmental Pathology, Toxicology and Oncology 
Edlich R, et al. Scientific documentation of the relationship of vitamin D deficiency and the development of cancer. 2009;28(2):133-41. 

Topic: 
Does vitamin D deficiency increase cancer risk?

Background:

It is well-known that vitamin D is important for optimal skeletal growth, yet most physicians do not appreciate the role of vitamin D deficiency in predisposing people to the development of cancer.

Study Type:

Review paper

Results:

The authors present data showing that:

  • Insufficient vitamin D is associated with developing cancer of the colon/rectum, prostate and ovaries, as well as multiple myeloma (a bone marrow cancer).
  • There is an inverse relationship between vitamin D levels and breast cancer incidence. (In other words, the higher a woman's vitamin D levels, the less likely she is to develop breast cancer and vice versa.)
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Critical Reviews in Clinical Laboratory Sciences

Gocek E, Studzinski GP. Vitamin D and differentiation in cancer. 2009;46(4):190-209.

Topic: 
What is the relationship between vitamin D and cell differentiation in cancer?

Background:

One distinguishing feature of cancer cells is that they lack differentiation — i.e. the ability to specialize in specific functions — yet they still have the potential to divide and proliferate.

Study Type:

Review paper

Results:

The authors present data showing that:

  • Review the current understanding of how vitamin D can help tumor cells differentiate into "nearnormal" cells.
  • Outline the existing, though fragmentary, knowledge of the signaling pathways that lead colon, breast, prostate, squamous cell carcinoma, osteosarcoma and myeloid leukemia cancer cells to differentiate, thus inhibiting cell proliferation.


Anticancer Research 

Köstner K, et al. The relevance of vitamin D receptor (VDR) gene polymorphisms for cancer: a review of the literature. 2009 Sep;29(9):3511-36. 

Topic: 
Can mutations of the vitamin D receptor (VDR) gene increase the risk of developing various cancers?

Background:

In recent years, the relevance of mutations in the VDR gene to the development of various types of cancer has been investigated by a great number of studies, often showing controversial results.

Study Type:

Review paper

Results:

While the authors acknowledge that "at present, it is still not possible to make any definitive statements about the importance of the VDR genotype for cancer occurrence," they found the strongest associations between a VDR mutation and increased risk of breast cancer, prostate cancer and malignant melanoma. 

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Vitamin D Mechanism of Action

Vitamin D deficiency has been found in patients with prostate and other cancers. Calcitriol (1,25-dihydroxyvitamin D3), the active form of vitamin D, can stop the growth and division of prostate cancer cells by inducing cell-cycle arrest in stage G1. This means the cancer cell is stopped from dividing while it is still in the early stages of growth. The cell-cycle arrest is accomplished by down-regulating (or decreasing the expression of) a gene called c-Myc, which promotes tumor growth.