Cancer patients with higher levels of vitamin D at diagnosis tend to have better outcomes than patients who are vitamin D-deficient, a meta-analysis suggests.
Researchers found the association between vitamin D and prognosis was most pronounced in patients with breast cancer, colorectal cancer, and lymphomas.
The team observed an association between vitamin D and prognosis in other cancers as well, but the correlations were not significant.
Hui Wang, MD, PhD, of the Chinese Academy of Sciences in Shanghai, China, and colleagues conducted this research and reported their results in the Journal of Clinical Endocrinology & Metabolism.
The team analyzed data from 25 studies including 17,332 cancer patients. In most of the studies, patients had their vitamin D levels tested before they underwent any cancer treatment.
The analysis showed that, overall, a 10 nmol/L increase in vitamin D levels was associated with a 4% increase in survival.
The strongest links between vitamin D levels and survival were seen in breast cancer, colorectal cancer, and lymphomas. There was less evidence of a connection in patients with leukemias, lung cancer, gastric cancer, prostate cancer, melanoma, or Merkel cell carcinoma, but the available data were positive.
There were 2 studies evaluating the association between survival and vitamin D levels in leukemia patients.
Vitamin D insufficiency was associated with poor overall survival in patients with newly diagnosed chronic lymphocytic leukemia, although this was not statistically significant. The hazard ratio (HR) was 0.68 (P=0.07).
For acute myeloid leukemia, patients with vitamin D levels that were considered insufficient (20-31.9 ng/mL) or deficient (<20 ng/mL) had worse overall survival (HR=0.65) and disease-free survival (HR=0.65) than patients with normal vitamin D levels.
There were also 2 studies evaluating the association between survival and vitamin D levels in lymphoma patients. The results showed that patients with the highest vitamin D levels had better overall survival than those with the lowest vitamin D levels (HR=0.48, P<0.001).
Lymphoma patients in the highest quartile of vitamin D levels also had a lower risk of cancer-specific mortality (HR=0.50, P<0.001) and better disease-free survival (HR=0.80, P=0.04).
Similarly, higher vitamin D levels were significantly associated with reduced cancer-specific mortality for patients with colorectal cancer (P=0.005) and improved disease-free survival for patients with breast cancer (P<0.001).
For overall survival, the HR for the highest vs lowest quartile of vitamin D levels was 0.55 for colorectal cancer patients and 0.63 for breast cancer patients.
Based on these results, Dr Wang concluded, “Physicians need to pay close attention to vitamin D levels in people who have been diagnosed with cancer.”
