The body naturally produces vitamin D after exposure to sunlight and absorbs it from certain foods. In addition to helping the body absorb the calcium and phosphorus needed for healthy bones, vitamin D affects a variety of biological processes by binding to a protein called a vitamin D receptor. This receptor is present in nearly every cell in the body.
"By reviewing studies that collectively examined vitamin D levels in 17,332 cancer patients, our analysis demonstrated that vitamin D levels are linked to better outcomes in several types of cancer," said one of the study''s authors, Hui Wang, MD, PhD, Professor of the Institute for Nutritional Sciences at the Shanghai Institutes for Biological Sciences at the Chinese Academy of Sciences in Shanghai, China. "The results suggest vitamin D may influence the prognosis for people with breast cancer, colorectal cancer and lymphoma, in particular."
The meta-analysis looked at the results of 25 separate studies that measured vitamin D levels in cancer patients at the time of diagnosis and tracked survival rates. In most of the research, patients had their vitamin D levels tested before they underwent any treatment for cancer. The study found a 10 nmol/L increase in vitamin D levels was tied to a 4 percent increase in survival among people with cancer.
Researchers found the strongest link between vitamin D levels and survival in breast cancer, lymphoma and colorectal cancer. There was less evidence of a connection in people with lung cancer, gastric cancer, prostate cancer, leukemia, melanoma or Merkel cell carcinoma, but the available data were positive.
"Considering that vitamin D deficiency is a widespread issue all over the world, it is important to ensure that everyone has sufficient levels of this important nutrient," Wang said. "Physicians need to pay close attention to vitamin D levels in people who have been diagnosed with cancer."
Other authors of the study include: Mian Li, Peizhan Chen, Jingquan Li, Ruiai Chu and Dong Xie of the Institute for Nutritional Sciences at the Shanghai Institutes for Biological Sciences.
The study, "The Impacts of Circulating 25-Hydroxyvitamin D Levels on Cancer Patient Outcomes: A Systematic Review and Meta-Analysis
," is scheduled to appear in the July issue of JCEM