A malignant tumor contains not just cancer cells but many types of cells, some of which affect how fast a tumor may grow or spread. Among them are a group of immune system cells called T lymphocytes, or T cells, that can target tumor cells and limit their growth. Having a tumor with more T cells correlates with a better prognosis.
The study, published in the journal Gut, included 318 people who had developed colorectal cancer and 624 matched controls. All had vitamin D levels measured before the appearance of any cancers.
The higher the blood levels of vitamin D, the less likely people were to develop colorectal tumors. Vitamin D, the authors suggest, interacts with the immune system to prevent the growth of this type of malignancy.
“This study really shows that vitamin D has an effect on immunity,” said the senior author, Dr. Shuji Ogino, an associate professor of pathology at the Dana-Farber Cancer Institute in Boston, “and it’s the first study to show that in a human population. Vitamin D boosts immunity not just in cancer, but in fighting infections as well.”
Source: New York Times