High-dose vitamin D3 for CRC: befuddling findings

  • Ng K & al.
  • JAMA
  • 9 Apr 2019

  • curated by Emily Willingham, PhD
  • Univadis Clinical Summaries
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Takeaway

  • 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.

Key results

  • 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).

Study design

  • 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. 

Limitations

  • Small, demographically homogeneous sample.
  • Not powered to detect OS differences.

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