High-Dose Vitamin D3 Fails To Improve Metastatic Colorectal Cancer Outcomes

A double-blind randomized phase 3 clinical trial led by Dana-Farber Cancer Institute researchers and conducted across several hundred cancer centers in the U.S. tested the addition of high-dose vitamin D3 to standard treatment for patients with untreated metastatic colorectal cancer. More than 450 patients received standard chemotherapy plus bevacizumab and were randomized to high-dose or standard dose vitamin D3. The team observed no additional concerning side-effects or toxicities with the addition of high-dose vitamin D3.

However, the addition of high-dose vitamin D3 to standard treatment did not delay the progression of cancer more so than standard-dose vitamin D3, according to the team’s analysis after a median 20-month follow-up. A potential benefit for high-dose vitamin D3 was observed for patients with left-sided disease (i.e., primary tumors that arise in the descending colon, sigmoid colon, or rectum) and requires further investigation.