TUESDAY, Oct. 17, 2006 (HealthDay News) -- Women with early stage breast cancer have significantly higher levels of vitamin D in their blood than women with cancer that has spread to other parts of the body, a small study found.
This could mean that a lack of vitamin D somehow plays a role in the spread of the disease. However, it's way too early to make specific recommendations based on the findings, experts say.
"It's an interesting concept but it's a small study and needs to be done in a large, randomized, controlled fashion," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La.
"There are no real practical implications as such yet, from a lifestyle point of view, all women (and men) should eat a balanced diet and ensure they are exposed to some sunlight, as this is important in vitamin D synthesis," added the study's lead author, Dr. Carlo Palmieri, of Cancer Research UK Laboratories and Imperial College, London.
Previous research has hinted at a role for vitamin D in cancer prevention. In laboratory studies, vitamin D stopped cancer cells from dividing and also contributed to cell death. And epidemiological reviews suggest that breast cancer incidence and mortality is lower in latitudes with more sunlight.
Sunlight is critical for health because it allows the skin to synthesize vitamin D. Another recent study found that vitamin D may lower the risk of breast and ovarian cancer. Vitamin D is also known to enhance the function of certain genes -- including p21, which is involved in the cell life cycle -- while inhibiting the function of others.
For the new study, published online Monday in the Journal of Clinical Pathology, the researchers measured vitamin D levels, parathyroid hormone and calcium in 204 women with early breast cancer; 279 women with invasive breast cancer; and 75 women with advanced breast cancer. All participants were Caucasian.
Women with early stage breast cancer had higher levels of vitamin D and lower levels of parathyroid hormone than women with advanced disease. Calcium levels were similar.
The exact reason for the disparities isn't clear, the study authors stated. Nor is it clear that there's a cause-and-effect relationship between the presence of vitamin D and cancer prognosis.
"Our study showed an association," Palmieri said. "In other words, women with advanced breast cancer had lower vitamin D, and the question is whether this is cause or effect."
Still, Palmieri said, the findings should be viewed in the context of all the other available data on vitamin D -- data that seem to support the hypothesis that vitamin D is somehow involved in breast cancer.
"Our data lends weight to the hypothesis that vitamin D has a role in the pathogenesis and progression of breast cancer," he said.
One next step for researchers, Palmieri said, would be to see if maintaining normal levels of vitamin D -- by taking supplements -- in women diagnosed with early or advanced breast cancer improved their outcomes, when used in conjunction with the latest therapies.
Visit the National Cancer Institute for more on breast cancer.