A team of US-based researchers has concluded that high-dose vitamin D3 does not provide any additional benefit for patients suffering from metastatic colorectal cancer. This conclusion was reached following a randomized phase 3 clinical trial led by researchers from the Dana-Farber Cancer Institute in the US. The trial was conducted across several hundred cancer centers, testing the efficacy of adding high-dose vitamin D3 to the standard treatment regimen for patients with untreated metastatic colorectal cancer.
The standard treatment typically involves chemotherapy plus bevacizumab, a medication used to treat various types of cancer. In this trial, over 450 patients received this standard treatment and were then randomized to receive either high-dose or standard dose vitamin D3. The researchers observed no additional concerning side-effects or toxicities with the addition of high-dose vitamin D3. This is an important finding, as it suggests that high-dose vitamin D3 can be safely administered to patients without exacerbating the side effects of their existing treatment regimen.
However, the primary objective of the trial was to determine whether high-dose vitamin D3 could delay the progression of cancer more so than standard-dose vitamin D3. After a median 20-month follow-up period, the researchers found that this was not the case. Interestingly, the researchers did observe a potential benefit for high-dose vitamin D3 in a specific subset of patients. Those with left-sided disease, which refers to primary tumors that arise in the descending colon, sigmoid colon, or rectum, appeared to derive some benefit from high-dose vitamin D3. However, the researchers noted that this finding requires further investigation.
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. The researchers hypothesized that the addition of high-dose vitamin D3 to standard therapy could potentially improve progression-free survival. However, the results of the SOLARIS trial suggest that high-dose vitamin D3 cannot be recommended as a treatment for patients with untreated metastatic colon cancer.
This finding is significant, as it challenges the prevailing belief that high-dose vitamin D3 could be a potential adjunctive treatment for metastatic colorectal cancer. It also underscores the importance of conducting rigorous clinical trials to test the efficacy of potential treatments, even those that seem promising based on preliminary research.
The results of the SOLARIS trial are consistent with the findings of previous studies that have also questioned the efficacy of high-dose vitamin D3 for cancer treatment. For instance, a 2019 study published in the New England Journal of Medicine found that high-dose vitamin D3 did not improve overall survival in patients with advanced or metastatic colorectal cancer. Similarly, a 2020 study published in the Journal of Clinical Oncology found that high-dose vitamin D3 did not improve progression-free survival in patients with metastatic colorectal cancer.
