Vitamin D deficiency has been implicated in a variety of cancers (here, here, and here). Now a study found that vitamin D levels are linked to the long-term outcome in women with breast cancer. Researchers found that after 7 years, women with the highest levels of vitamin D had about a 30 percent better likelihood of survival from breast cancer than women with the lowest levels of vitamin D, The study put women into one of three groups based on their levels of vitamin D (as measured in the blood 2 months after the initial breast cancer diagnosis): deficient - levels below 20.0 ng/mL; insufficient - 20.0 to 29.9 ng/mL; and sufficient - greater than or equal to 30.0 ng/mL. They found that almost half of the women were vitamin D deficient, and another third were insufficient.
The researchers said the findings "provide compelling observational evidence for inverse associations between vitamin D levels and risk of breast cancer progression and death". In other words, the higher the vitamin D levels, the better the outcome. NOTE: Good vitamin D levels can usually be obtained with one 1000 IU supplement of vitamin D3 per day. Or expose bare skin to sunlight - after all, it is called the "sunshine vitamin". From Medical Xpress:
Higher vitamin D levels associated with better outcomes in breast cancer survivors
Women with higher vitamin D levels in their blood following a breast cancer diagnosis had significantly better long-term outcomes, according to new research from Kaiser Permanente and Roswell Park Cancer Institute....Vitamin D is a nutrient best known for its role in maintaining healthy bones; conversely, vitamin D deficiency has been associated with the risk for several cancers.
Common sources of vitamin D include sun exposure, fatty fish oils, vitamin supplements, and fortified milks and cereals. While the mechanisms for how vitamin D influences breast cancer outcomes are not well understood, researchers believe it may be related to its role in promoting normal mammary-cell development, and inhibiting the reproduction of and promoting the death of cancer cells.
"We found that women with the highest levels of vitamin D levels had about a 30 percent better likelihood of survival than women with the lowest levels of vitamin D," said Lawrence H. Kushi, ScD....principal investigator of Kaiser Permanente's Pathways study of breast cancer survivorship. The current study included 1,666 Pathways study members who provided samples between 2006 and 2013....had a diagnosis of invasive breast cancer in 2006. Participants provided blood samples within two months of diagnosis and answered questions about diet, lifestyle and other risk factors, with follow-ups at six months and at two, four, six and eight years.
"With the extremely rich data sources from a large sample size, we were able to prospectively analyze three major breast cancer outcomes—recurrence, second primary cancer and death," said Song Yao, PhD, associate professor of oncology at Roswell Park Cancer Institute and the study's lead author....In addition to lower overall mortality among all breast cancer survivors studied, the researchers found even stronger associations among premenopausal women in the highest third of vitamin D levels for breast-cancer-specific (63 percent better), recurrence-free (48 percent better) and invasive-disease-free survival (42 percent better), during a median follow up of seven years. [Original study]