- For untreated metastatic colorectal cancer (CRC), adding high-dose vitamin D3 to standard chemotherapy yields no PFS benefit over standard-dose D3.
- The authors say that the multivariable HR for PFS or death in this phase 2 trial (the SUNSHINE trial) did show significance.
Why this matters
- Observational studies have suggested a benefit of high-dose vitamin D supplementation for these patients.
- An accompanying editorial says the results could arise from chance or suggest that an insufficient dose was used for patients with worse baseline deficiency.
- Median PFS for high dose (8000 IU/day for 2 weeks; 4000 IU/day thereafter) vs standard dose (400 IU/day):
- 13.0 (95% CI, 10.1-14.7) vs 11.0 (95% CI, 9.5-14.0) months, respectively (log-rank P=.07).
- With adjustment, on multivariable analysis, HR for PFS or mortality at 22.9-month median follow-up:
- 0.64 (1-sided; 95% CI, 0-0.90; P=.02).
- Median survival in both groups was 24.3 months (no difference).
- Double-blind, randomized trial, 139 patients with advanced or metastatic CRC, 11 US centers, March 2012-November 2016.
- Chemotherapy plus high-dose vitamin D (n=69) or standard dose (n=70).
- Outcome: PFS (1-sided tests).
- Funding: NIH, National Cancer Institute.
- Small, demographically homogeneous sample.
- Not powered to detect OS differences.