The reduced incidence in developing advanced cancer in patients at least 50 years and older was more prominent in those with normal weight vs. overweight or obesity.
Vitamin D supplements correlated with a reduced incidence of advanced cancer, especially in patients with normal weight, according to study results published in JAMA Network Open.
“These findings suggest that vitamin D may reduce the risk of developing advanced cancers,” said Dr. Paulette Chandler, assistant professor of medicine at Harvard Medical School and associate epidemiologist in the division of preventive medicine at Brigham and Women’s Hospital, in an interview with CURE®. “No other treatment or supplement has been identified that is associated with an over 15% reduction in advanced total cancer risk. Vitamin D is a supplement that’s readily available, cheap and has been used and studied for decades, and has a great safety profile.”
The VITAL trial compared the benefits and risks of vitamin D and marine omega-3 fatty acids — or fish oil — with placebo to prevent cancer and cardiovascular disease in 25,871 patients (mean age, 67.1 years; 51% women), which included men 50 years and older, and women 55 years and older. All patients did not have a history of cancer or cardiovascular disease upon enrolling in the trial. Given that this was a randomized-controlled trial, patients were randomly assigned vitamin D supplementation, omega-3 fatty acids, both agents or placebo.
The primary end point for this analysis was the rate of a composite, or combined, end point of metastatic and/or fatal cancer and the time from when a patient enrolled in the trial to a diagnosis of metastatic or fatal cancer. Researchers also monitored how body mass index (BMI) potentially modified the effect of vitamin D supplementation on developing metastatic or fatal cancer.
During a median intervention, or treatment, period of 5.3 years, 1,617 patients developed invasive cancer. A previous report from this trial noted that cancer incidence did not differ by treatment groups. Researchers found that patients assigned vitamin D had a significantly greater reduction in advanced cancers compared with those assigned placebo (1.7% vs. 2.1%).
Patients with normal BMI, defined as less than 25, who were assigned vitamin D had a significant reduction in incident metastatic or fatal cancer. This was not observed for overweight (BMI between 25 and 30) and obesity (BMI ≥ 30).
“A dynamic interplay between obesity, inflammation and immune system activation may contribute to the differential response to vitamin D3,” Chandler explained. “Vitamin D and immunity share an important connection because vitamin D receptors are on the surfaces of many cells in the immune system. Vitamin D may help bolster and regulate the immune system. Receptors are like a lock in a door that is opened with the right key. Opening the lock may start a cascade of actions that changes how a cell behaves.”
Chandler added that findings from this study may support further research into this specific area.
“Our findings, along with results from previous studies, support the ongoing evaluation of vitamin D supplementation for preventing metastatic cancer — a connection that is biologically plausible,” Chandler said. “Additional studies focusing on cancer patients and investigating the role of BMI are warranted. Vitamin D deficiency is common among cancer patients, with one study reporting rates of vitamin D deficiency as high as 72% among cancer patients. There is also evidence that higher amounts of body fat are associated with increased risk for several cancers.”
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