Does Vitamin D Help Breast Cancer Patients?
Breast cancer patients who have high levels of naturally-occurring vitamin D in their blood may have a better chance of surviving the disease than patients with low levels, according to new research.
The findings, published in the journal Anticancer Research, suggest that breast cancer patients with low levels of vitamin D may benefit from having their blood concentrations of the vitamin adjusted, which scientists said may increase chances of survival by as much as 50 percent.
Many previous studies have focused on how vitamin D levels in people without cancer may reduce potential cancer risk. The new research is one of the few studies that have examined the association between a breast cancer patient’s vitamin D levels at the time of diagnosis with the risk of dying from the disease.
The research team from University of California, San Diego School of Medicine conducted a meta-analysis of five different studies between 1996 and 2010 that examined the link between breast cancer and something called 25-hydroxyvitaminD—a byproduct that the body produces from ingesting vitamin D.
The combined studies involved approximately 4,500 breast cancer patients, whom researchers followed for nearly a decade. The studies’ participants were divided into three groups based on whether they had high, average or low levels of 25-hydroxyvitaminD in their blood.
After analyzing the data, the researchers found that the women with high levels of the vitamin D byproduct—defined as an average of 30 nanograms per milliliter (ng/ml)—were 50 percent more likely to survive breast cancer than women with low levels, or an average of 17 ng/ml.
The results of the study add evidence to the theory that the byproduct of vitamin D ingestion may activate a protein that inhibits aggressive cancer cell division, which may explain the study’s findings. Further research is needed, however, in order for the relationship between vitamin D metabolites and tumor growth to become definitive.
Although the evidence points to higher breast cancer survival rates among patients with higher vitamin D levels, it remains unclear whether the link between vitamin D and breast cancer is causal.
“It could be that certain patients with more aggressive disease tend to have lower vitamin D levels for other reasons,” explained Asma Ali Dilawari, MD, from MedStar Harbor Hospital, who was not involved with the new study. Only further clinical trials could rule out this possible explanation for the study’s findings.
The researchers said that their findings suggest that breast cancer patients with low vitamin D levels may benefit from having their levels adjusted to within normal range, or 30 to 80 ng/ml, regardless whether advanced breast cancer causes lower vitamin D levels or vice versa.
The research team involved in the study added that with permission from their health care provider, there is no reason why breast cancer patients should worry about increasing vitamin D intake to meet the recommended daily amounts, which is about 600 IU per day for adults up to age 70, according to the National Institutes of Health.
Dilawari noted, however, that scientists do not know the “perfect” level for vitamin D in breast cancer patients. “Therefore, the recommendations for 500 to 1000 IU/day may seem a bit random,” she said. Dilawari also warned that the research community is currently lacking guidelines about how quickly to supplement patients with vitamin D and when to re-check levels and added that ever supplement comes with health risks.
It remains unclear whether the link between vitamin D and breast cancer is causal, as researchers said that advanced breast cancer may cause reduced vitamin D levels and not the other way around. The findings may lead to future innovations in breast cancer therapy, but further research is needed in order to confirm the recent findings.
Experts advised that breast cancer patients refrain from increasing vitamin D intake before they discuss it with their health care provider.
Dilawari, Asma Dr. E-mail interview. 13 March 2014.