Vitamin D may benefit Breast Cancer Patients: "Only 24 percent of women in the study had sufficient blood levels of D at the time they were first diagnosed with breast cancer. Those who were deficient were nearly twice as likely to have their cancer recur or spread over the next 10 years, and 73 percent more likely to die of the disease.... But people shouldn't start downing supplements... Experts don't agree on how much vitamin D people need or the best way to get it, and too much can be harmful. They also don't know whether getting more vitamin D can help when someone already has cancer.... We have no idea whether correcting a vitamin D deficiency will in any way alter these outcomes,'' said Dr. Julie Gralow, a cancer specialist at the University of Washington in Seattle."