Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements .
The effects observed for vitamin D3 supplementation remained unchanged when grouped by various characteristics .
However , for vitamin D2 supplementation , increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods .
Conclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease , cancer , and other causes .
Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with  mortality from cardiovascular , cancer , or other conditions  , under various circumstances .
Prognostic effects of 25-hydroxyvitamin D levels in early breast cancer.
PURPOSE Vitamin D has been linked to breast cancer risk , but prognostic effects are unknown . Such effects are biologically plausible given the presence of vitamin D receptors in breast cancer cells , which act as nuclear transcription factors to regulate gene activity . PATIENTS AND METHODS The study was conducted in a prospect i ve inception cohort of 512 women with early breast cancer diagnosed 1989 to 1996 .  Vitamin D levels were measured in stored blood . Clinical , pathologic , and dietary data were accessed to examine prognostic effects of vitamin D. RESULTS Mean age was 50.4 years , mean vitamin D was 58.1 + /- 23.4 nmol/L.  Vitamin D levels were deficient ( < 50 nmol/L ) in 37.5 % of patients , insufficient ( 50 to 72 nmol/L ) in 38.5 % of patients , and sufficient ( > 72 nmol/L ) in 24.0 % of patients . There was little variation in mean vitamin D levels between summer and winter months . Mean follow-up was 11.6 years ; 116 women had distant recurrences , and 106 women died . Women with deficient vitamin D levels had an increased risk of distant recurrence ( hazard ratio [ HR ] = 1.94 ; 95 % CI , 1.16 to 3.25 ) and death ( HR = 1.73 ; 95 % CI , 1.05 to 2.86 ) compared with those with sufficient levels . The association remained after individual adjustment for key tumor and treatment related factors but was attenuated in multivariate analyses ( HR = 1.71 ; 95 % CI , 1.02 to 2.86 for distant recurrence ; HR = 1.60 ; 95 % CI , 0.96 to 2.64 for death ) . CONCLUSION Vitamin D deficiency may be associated with poor outcomes in breast cancer
Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements .
The effects observed for vitamin D3 supplementation remained unchanged when grouped by various characteristics .
However , for vitamin D2 supplementation , increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods .
Conclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease , cancer , and other causes .
Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with  mortality from cardiovascular , cancer , or other conditions  , under various circumstances .