The Study(s): Vitamin D is determined to have a comeback in 2019. The phase 2 SUNSHINE trial enrolled US patients with metastatic colorectal cancer receiving mFOLFOX + bevacizumab, and randomized them to the addition of vitamin D3 at either a high-dose (8000 IU daily x 2 weeks → 4000 IU daily, n=69) or low-dose (400 IU daily, n=70). The primary endpoint of progression-free survival (PFS) was increased from a median of 11 → 13 months in the high-dose arm, producing a hazard ratio significant only on multivariate analysis (HR 0.64). In the same issue come results of the AMATERASU trial that enrolled Japanese patients with completely resected GI cancer (spanning esophagus to rectum), and randomized them to maintenance vitamin D3 (2000 IU daily, n=251) or placebo (n=166). The primary endpoint of PFS was increased from 69 → 77% at 5 years in the vitamin D3 arm, producing a hazard ratio significant only on age-adjusted analysis (HR 0.66).
Bottom Line: Two prospective trials show numeric improvements in GI cancer outcomes with the addition of relatively high-dose vitamin D3, both significant with some statistical finesse. | Ng & Urashima, JAMA 2019