Full-text evidence summary

Breast cancer Introduction

Breast cancer is the cancer for which the evidence of a beneficial role of vitamin D is strong.

Breast cancer is the cancer for which the evidence of a beneficial role of vitamin D is strong. There is ample evidence from numerous ecological (geographical), cross-sectional (pictures in time), prospective (looking forward), and case-control studies (looking forward with a control group), meta-analyses (combination) of such studies, and laboratory investigations of mechanisms. A meta-analysis of prospective studies indicates that breast cancer incidence falls as a power law fit vs. serum 25-hydroxyvitamin D [25(OH)D] level, with lowest risk for those with serum 25(OH)D levels near 150 nmol/L (60 ng/mL). Survival rates after diagnosis are higher for those with higher serum 25(OH)D levels at time of diagnosis.

Breast cancer is one of the most frequent cancers among women in Western developed countries. Important risk factors for breast cancer include a diet high in animal products12, consumption of alcoholic beverages234, reproductive factors54, and night shift work6. Much of the risk for breast cancer comes from integrated lifetime estrogen exposure, either endogenous (produced in the body)78 or exogenous (taken orally)9. A diet high in animal products early in life leads to increased endogenous estrogen production over the entire lifetime. Night shift work is associated with reduced melatonin production, and melatonin can reduce the risk of breast cancer101112.

That vitamin D might reduce the risk of breast cancer was proposed in 1989 based on effects on breast cancer cell proliferation13. Ecological studies (populations defined geographically) using indices for solar ultraviolet-B (UVB) dose followed quickly1415. Since then, there have been numerous ecological and observational studies of incidence and mortality rates with respect to solar ultraviolet-B (UVB) irradiance, serum 25(OH)D levels, and oral vitamin D intake.

Page last edited: 22 August 2011


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