Breast cancer patients deficient in vitamin D

Women who had a vitamin D deficiency when they were diagnosed with breast cancer were 94% more likely to have their cancer metastasize and 73% more likely to die within 10 years.

The team also found that only 24% of the women in its study had what are normally considered adequate levels of vitamin D at the time of the diagnosis.

The study represents "the first time that vitamin D has been linked to breast cancer progression," said Dr. Pamela Goodwin of Mount Sinai Hospital in Toronto, who led the study.

The results are "very provocative," said Dr. Joanne Mortimer, a breast cancer specialist at City of Hope Comprehensive Cancer Center in Duarte, who was not involved in the study.

"There is some evidence that some of the drugs we use to treat breast cancer, such as aromatase inhibitors, need vitamin D to be activated and metabolized."

Some women who take the drugs get joint aches, Mortimer said, and when they are put on vitamin D, "they get better."

The study was released by the American Society for Clinical Oncology.

Separately, a team from UC San Diego reported Thursday in the Breast Journal that global breast cancer incidence was linked to the amount of sunlight received annually. The skin makes vitamin D when exposed to sunlight.