Breast cancer: vitamin D reduces mortality cases

In patients with breast cancer, high vitamin D levels are associated with lower mortality rates. Women affected by the disease with high levels of a vitamin metabolite, 25(OH)D (25-hydroxycholecalciferol), have double the survival rate compared to those with lower concentrations. Vitamin D could therefore become an adjuvant to conventional anticancer therapies.

This was discovered by researchers at the University of California, San Diego (USA). The meta-analysis study, published in the journal Anticancer Research, was conducted on the results of 5 clinical trials.

Vitamin D and breast cancer

Vitamin D is present in many animal- and plant-based foods and exists in two forms: ergocalciferol or vitamin D2, and cholecalciferol or vitamin D3. Its main function is to maintain normal calcium and phosphorus levels in the blood and promote calcium absorption, contributing to healthy bones. Numerous discoveries have suggested that vitamin D may also have a protective role against hypertension, cancer, and various autoimmune diseases. In particular, recent studies have shown a link between low vitamin D levels and a higher risk of premenopausal breast cancer.

More vitamin D, higher survival probability

The statistical analyses of the study were conducted on data from 4,443 patients, considering vitamin D concentration at diagnosis and during a 9-year follow-up period. Researchers classified women based on cholecalciferol concentration; those with the highest level had an average of 30 ng/mL, while those with the lowest had 17 ng/mL. Previous studies showed that the average vitamin D concentration in breast cancer patients was about 17 ng/mL. The meta-analysis revealed that women in the group with higher vitamin D levels had half the risk of death compared to those in the lower-level group. 

The study results demonstrate that adequate serum vitamin D concentration is associated with lower mortality in breast cancer patients. However, reverse causality cannot be ruled out: it is possible that in more severe cases, and thus with earlier death, serum 25(OH)D concentration is lower. If so, vitamin D could be a signaling molecule of severe cancer rather than a factor causing longer or shorter survival. Further studies will be necessary to understand this relationship, but in the meantime, there are no contraindications to recommend vitamin D supplements sufficient to reach serum concentrations above 30 ng/mL.  

Source: Sharif B. Mohr, Edward D. Gorham, June Kim, Heather Hofflich and Cedric F. Garland “Meta-analysis of Vitamin D Sufficiency for Improving Survival of Patients with Breast Cancer” Anticancer Research. March 2014 vol. 34 no. 3 1163-1166