Vitamin D from dietary intake and sunlight exposure and the risk of hormone-receptor-defined breast cancer.
Blackmore KM, Lesosky M, Barnett H, Raboud JM, Vieth R, Knight JA.
Am J Epidemiol. 2008 Oct 15;168(8):915-24. Epub 2008 Aug 27.
PMID: 18756015
doi:10.1093/aje/kwn198
This study suggests that vitamin D is associated with a reduced risk of breast cancer regardless of ER/PR status of the tumor. Future studies with a larger number of receptor-negative and mixed tumors are required.