There has been interest for some time now about the role of vitamin D levels in the blood and the potential protective benefits of adequate levels in the prevention of breast, colon and other adenocarcinomas.
This meta-analysis was conducted using a PUBMED search for observational studies of serum 25(OH)D and risk of breast cancer between 1966 and 2010. Articles were included if they were published in medical journals, were prospective or historical follow-up studies and if they articles reported survival or mortality rates in relationship to quintiles of serum 25(OH)D. A total of 77 studies were identified but after review by these two researchers, only five studies were eligible for inclusion.
A higher serum concentration of 25(OH)D was associated with lower case- fatality rates in breast cancer patients. Three of the five studies found that serum vitamin D in the highest quantile was associated with significantly lower mortality rates than serum vitamin D levels in the lowest quantile. Two other studies found a trend in that same direction. Breast cancer patients with the highest concentration of 25(OH)D had approximately half the mortality rate compared to those with the lowest concentration.
Commentary: Laboratory studies have found anticancer benefits of metabolites of vitamin D on cell differentiation, apoptosis (cell death) and angiogenesis (blood supply to tumor sites) of breast tumors. The hypothesis is that breast cancer survival may be influenced by serum levels of vitamin D and its effect on maintaining cell differentiation, promoting apoptosis and inhibiting angiogenesis. In terms of clinical trials of vitamin D for prevention, I am aware of one such trial where 1,000 IU of vitamin D daily with calcium, showed a 77% reduction in incidence of all combined invasive cancer, including breast cancer.
Vitamin D testing is a simple test, called a serum 25(OH)D. I routinely test breast cancer patients for this and assure that they have adequate vitamin D levels of 30-80 ng/ml. That said, there has been some concern about levels > 40 ng/ml and increased risk of pancreatic cancer. My goal therefore, is 30-40 ng/ml. Vitamin D supplementation is by and large safe and definitely one of the most inexpensive vitamins to take. And don’t forget the sunshine— just harder to determine exposure necessary for adequate serum levels– plus potential negative effects of too much exposure and increased skin aging, and precancerous and cancerous skin lesions.
Reference
Mohr S, Gorham E, Kim J, et al. Meta-analysis of Vitamin D sufficiency for improving survival of patients with breast cancer. Anticancer Research 2014;34:1163-1166.
