Vitamin D and prognosis in breast cancer

This article evaluated the association between vitamin D levels and risk of breast cancer recurrence (return of the cancer) after treatment.

Vitamin D is both a nutrient we eat and a hormone our bodies make, that helps regulate the flow of calcium into the bloodstream and is crucial for normal bone development. Unlike other vitamins, we do not need to get vitamin D from food. A main source of vitamin D is made by our own bodies. It is made in the skin by the action of sunlight.

Vitamin D influences breast cancer cells to grow and multiply, but the relationship is not fully understood. A recent study found that women with early-stage breast cancer who lacked vitamin D were more likely to have their cancer recur in a distant part of the body and had poorer outcomes. More research is needed to confirm this finding, and it is not yet clear if taking vitamin D supplements would be helpful to prevent breast cancer recurrence.

This article reviewed 8 articles including a total of 5691 patients diagnosed with breast cancer. Four studies revealed that patients with low vitamin D levels were associated with lower survival. Also, all studies reported that low levels of vitamin D around the time of breast cancer diagnosis were associated with a higher risk of recurrence.

In summary, adequate vitamin D levels at diagnosis and after treatment might improve long-term survival of breast cancer patients.

Because of the observational nature of the study, it cannot be concluded that the association between low vitamin D levels and breast cancer is causal. Also, most of the studies analyzed in this article were performed in North America, a region deficient in vitamin D and the reported data might not be applied in other regions. Further studies are needed to confirm the beneficial role of vitamin D supplementation in lowering the risk of recurrence in breast cancer patients. 

Talk to your doctor about testing your vitamin D levels and about vitamin D supplementation.