Prevalence of vitamin D insufficiency among breast cancer survivors.

Background: Recent research has linked inadequate vitamin D levels with risk of breast cancer, but there are less data regarding the actual concentrations of vitamin D in women who have survived breast cancer. The objective of this study was to determine if vitamin D insufficiency is a prevalent problem for female breast cancer survivors who have completed treatment for breast cancer.

Methods: Ninety-nine breast cancer survivors and a control population of 54 women with no history of breast cancer participated in this study. Serum 25-hydroxy vitamin D concentrations were measured throughout 2007. Dietary and supplemental intake of vitamin D was assessed by a food frequency questionnaire. Zip code of residence was used to evaluate potential for skin production of vitamin D.

Results: Vitamin D insufficiency (<32 ng/mL) was observed in 76 of 99 (77%) of breast cancer survivors and 51 of 54 (94%) of controls. Women taking vitamin D supplements >1000 IU/d were less likely to exhibit vitamin D insufficiency, but supplementation did not guarantee sufficiency.

Conclusion: Vitamin D insufficiency appears to be prevalent among both controls and breast cancer survivors. Vitamin D status should be routinely evaluated for all women as part of regular preventive care if supplemental vitamin D intake is <1000 IU daily.