High-Dose Vitamin D3 Does Not Provide Benefit for Metastatic Colorectal Cancer

RESEARCH SUMMARY

Study Title: SOLARIS (Alliance A021703): A multicenter double-blind phase III randomized clinical trial of vitamin D combined with standard chemotherapy plus bevacizumab in patients with previously untreated metastatic colorectal cancer.

Publication: European Society for Medical Oncology 2024 Abstract LBA26

Dana-Farber Cancer Institute authors: Kimmie Ng, MD, MPH, Nadine McCleary, MD, MPH, Jeffrey A. Meyerhardt, MD, MPH

Summary: 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. 

Significance: The SOLARIS trial was inspired by previous research suggesting that higher levels of vitamin D in the blood are associated with improved survival for metastatic colorectal cancer and that the addition of high-dose vitamin D3 to standard therapy could potentially improve progression-free survival. The SOLARIS results suggest, however, that high-dose vitamin D3 cannot be recommended as a treatment for patients with untreated metastatic colon cancer.