Professor Hector Palmer and his co-researchers at the Vall d’Hebron Institute of Oncology in Barcelona, Spain, announced this morning the reason vitamin D may be an effective treatment early in the course of colon cancer, yet have little effect later, as the cancer becomes more widely spread.
Larriba MJ, Ordóñez-Morán P, Chicote I, Martín-Fernández G, Puig I, et al. 2011 Vitamin D Receptor Deficiency Enhances Wnt/β-Catenin Signaling and Tumor Burden in Colon Cancer. PLoS ONE 6(8): e23524. doi:10.1371/journal.pone.0023524
Vitamin D, in the form of the vitamin D receptor, slows the action of a key carcinogenic protein, beta-catenin. The problem arises when the tumor start to grow and, like in many cancers, reduces the presence of VDR, and finally there is simply not enough VDR to counteract the beta-catenin. And then the tumor takes over.
However, what I really like is Professor Palmer’s statement about what vitamin D can be expected to do. He says:
“In light of these findings, chronic vitamin D deficiency represents a risk factor in the development of more aggressive colon tumors.”
I also like United Press International’s summary of the study:
“Patients in the initial stages of colon cancer, when the vitamin D receptor still has a substantial presence in the cells, could benefit from vitamin D3, but this would not be useful in the advanced stages when the presence of the vitamin D receptor is very much reduced.”
That is pretty much what we see in studies of patients with colon cancer. High vitamin D levels appear to slow the growth of colon cancer only in some people, and we now can suspect those people are mainly patients with early stages of colon cancer and healthy numbers of VDRs.
It is a common and sad story. One of the first things most cancers do, early in their growth, is ramp-down the machinery that increases vitamin D production in the cell and ramp-up production of the machinery that gets rid of vitamin D in the cell.
What we hope (and some think it’s more than just hope) is that maintaining physiological vitamin D levels for years and years before you get cancer will ward off the disease. Although some studies support that, not all do, and only time will tell if our hope is grounded in reality.