By: Ernie Mundell
From: medscape.com
For women with breast cancer, vitamin D levels around the time of diagnosis might be related to long-term survival, a large prospective study showed.
Over a median of 12 years, women with sufficient vitamin D levels at breast cancer diagnosis had a 24% boost in overall survival compared to those with a vitamin D deficiency, the study found.
They also showed a 33% relative reduction in cardiovascular risk factors, such as diabetes and dyslipidemia.
“Correction of vitamin D deficiency, even during the time of diagnosis, may represent a simple local strategy to improve both cancer survival outcomes and cardiovascular risk factors in patients with breast cancer,” study co-author Alfredo Chua, Jr, MD, of Roswell Park Comprehensive Cancer Center in Buffalo, New York, told Medscape Medical News.
The study was published online in the Journal of the National Comprehensive Cancer Network.
The findings add to a body of research hinting that vitamin D deficiency — a common issue among US women with breast cancer — may worsen patients’ outcomes. Cohort studies have found a dose-response relationship between vitamin D status and overall survival in breast cancer. Meanwhile, a recent analysis from the Women’s Health Initiative trial found that participants who took vitamin D plus calcium were 7% less likely to die of any cancer over 22 years than those given placebos.
However, the supplement group also showed a comparable increase in cardiovascular mortality.
So for the new study, Chua and his colleagues looked at the relationship between vitamin D status and both breast cancer and cardiovascular outcomes.
The researchers tested serum 25-hydroxyvitamin D levels in a prospective cohort of almost 4000 patients at or near the time of breast cancer diagnosis. Vitamin D levels were deemed sufficient at 30 ng/mL or higher; insufficient at 20-29.9 ng/mL; and deficient at less than 20 ng/mL. The median follow-up was 12.2 years.
Overall, the study found that sufficient vitamin D status was associated with better survival vs deficiency (hazard ratio [HR], 0.76; P = .005), after adjustment for age, BMI, physical activity, smoking, race and ethnicity, tumor characteristics, and treatment types.
Sufficient vitamin D was also linked to improved second primary cancer-free survival (HR, 0.75; P = .003) and disease-free survival (HR, 0.82; P = .05).
All of those trends were restricted to patients with stage II or higher disease — most likely because of the generally good prognosis for patients with stage I breast cancer, Chua noted.
As for cardiovascular health, women with sufficient vitamin D had a lower likelihood of any incident cardiometabolic risk factor (subdistribution HR, 0.67; P < .001). They also showed a trend toward lower risk for cardiovascular disease, although no significant decline in risk for cardiovascular mortality was observed.
Azeez Farooki, MD, an endocrinologist at Memorial Sloan Kettering Cancer Center in New York City, reviewed the study for Medscape Medical News. He described it as “probably one of the best ones that have been done” on the relationship between vitamin D status and breast cancer survival.
Farooki said that in his own practice, where he sees patients whose bone health has been harmed by chemotherapy or radiation, he routinely checks vitamin D status.
But he said, the new findings alone are not enough to warrant testing vitamin D levels in all women diagnosed with breast cancer — or to offer them “definitive” advice on using supplements.
Farooki noted that while the researchers adjusted for various confounders, there may be other explanations for why women with sufficient vitamin D had better outcomes.
“What we really need is a randomized clinical trial to prove causality,” he said.
Chua agreed that such a trial is needed, especially since his team only tested for vitamin D levels at one point in time.
Barbara Jacoby is an award winning blogger that has contributed her writings to multiple online publications that have touched readers worldwide.